JAVA8-default、static JAVA8-default、staticdefault方法1.8之前出现的问题:开发了一个接口，后面实现该接口的实现类，都需要实现接口中定义的方法。1.8之后接口中使用default定义新增的方法后，其实现类可以不用实现该方法。例如Collection接口中新增了对stream的操作方法：stream()public interface Collection<E> extends Iterable<E> { default Stream<E> stream() { return StreamSupport.stream(spliterator(), false); } }其实现类就可以不用再实现stream()方法，这样对于版本兼容就比较好了。static 定义的方法可以通过接口直接调用该方法，例如：public interface Function<T, R> { static <T> Function<T, T> identity() { return t -> t; } }注意：接口中有default定义的方法实现了，但并不是抽象类。接口：可以被多个类实现。抽象类：继承了一个抽象类，就不能再继承另一个抽象类，因为类是单继承。实列自己用default实现一个接口package com.example.study.java8.method; /** * default使用 */ public class DefaultAction { public static void main(String[] args) { A a = ()->10; System.out.println(a.size()); System.out.println(a.isEmpty()); } public interface A{ int size(); //判断容器是否为空 default boolean isEmpty(){ return size()==0; } } }输出结果：10 false问题思考：当接口中定义default方法后，被多个类实现会不会出现冲突？问题思考，代码示例：package com.example.study.java8.method; public class DefaultActon2 { public void confuse(Object obj){ System.out.println("Object"); } public void confuse(int[] i){ System.out.println("int[]"); } public static void main(String[] args) { DefaultActon2 action = new DefaultActon2(); action.confuse(null); int [] arr = null; Object obj = arr; action.confuse(obj); } }输出结果：int[] Object思考：为什么传null，就是调用的int[]数组的方法，而下面的数组指向Object后，调用的时第一个object方法？因为当传null的时候，会调用声明更具体的方法，如上面的int[] i，明确定义了是一个int数组，而Object不是特别具体。Default方法解决多重继承冲突的三大原则1、类的优先级最高2、上一级接口，不管上一级接口有多少个类3、如果混淆了，就必须重写。类的优先级最高，示例：package com.example.study.java8.method; /** * 1、类的优先级最高 * 2、上一级接口，不管上一级接口有多少个类 */ public class DefaultAction3 { public static void main(String[] args) { A c = new C(); c.hello(); } public interface A{ default void hello(){ System.out.println("A-Hello"); } } public interface B extends A{ @Override default void hello(){ System.out.println("B-Hello"); } } public static class C implements B , A{ @Override public void hello() { System.out.println("C-Hello"); } } }输出结果：C-Hello混淆了，就必须重写，示例：package com.example.study.java8.method; /** * 1、类的优先级最高 * 2、上一级接口，不管上一级接口有多少个类 * 3、如果混淆了，就必须重写 */ public class DefaultAction4 { public static void main(String[] args) { A c = new C(); c.hello(); } public interface A{ default void hello(){ System.out.println("A-Hello"); } } public interface B { default void hello(){ System.out.println("B-Hello"); } } public static class C implements B , A{ // @Override // public void hello() { // System.out.println("C-Hello"); // } } }类C如果不重写会报错。必须重写C中hello方法。

CentOS安装Sentinel并自启动 CentOS安装Sentinel设置自启动1、下载下载地址https://github.com/alibaba/Sentinel/releases2、安装提前创建好安装路径、Jar包存放文件夹、脚本执行文件夹、日志存放文件夹mkdir /usr/local/ sentinel mkdir /usr/local/sentinel jar mkdir /usr/local/sentinel sh mkdir /usr/local/sentinel log将sentinel-dashboard-1.8.6.jar执行Jar包上传至jar文件夹3、脚本编写脚本sentinel.sh，按照自己路径、版本号调整，存放到上面新建的sh文件夹中。脚本如下：#!/bin/bash #这里可替换为你自己的执行程序，其他代码无需更改 SENTINEL_NAME=sentinel-dashboard-1.8.6.jar #使用说明，用来提示输入参数 usage() { echo "Usage: sh sentinel.sh [start|stop|restart|status]" exit 1 } #检查程序是否在运行 is_exist(){ pid=`ps -ef|grep $SENTINEL_NAME|grep -v grep|awk '{print $2}' ` #如果不存在返回1，存在返回0 if [ -z "${pid}" ]; then return 1 else return 0 fi } #启动方法 start(){ is_exist if [ $? -eq "0" ]; then echo "${SENTINEL_NAME} is already running. pid=${pid} ." else nohup java -Dserver.port=9100 -Dcsp.sentinel.dashboard.server=192.168.56.10:9100 -Dproject.name=sentinel-dashboard -jar /usr/local/sentinel/jar/$SENTINEL_NAME > /usr/local/sentinel/log/sentinellog.file 2>&1 & #nohup java -jar /usr/local/sentinel/jar/$SENTINEL_NAME > /usr/local/sentinel/log/sentinellog.file 2>&1 & echo "${SENTINEL_NAME} start success" fi } #停止方法 stop(){ is_exist if [ $? -eq "0" ]; then kill -9 $pid else echo "${SENTINEL_NAME} is not running" fi } #输出运行状态 status(){ is_exist if [ $? -eq "0" ]; then echo "${SENTINEL_NAME} is running. Pid is ${pid}" else echo "${SENTINEL_NAME} is NOT running." fi } #重启 restart(){ stop start } #根据输入参数，选择执行对应方法，不输入则执行使用说明 case "$1" in "start") start ;; "stop") stop ;; "status") status ;; "restart") restart ;; *) usage ;; esac进入/usr/local/sentinel/sh/文件夹下，执行命令修改权限chmod +x sentinel.sh注意：1、如果直接复制到windows中文本的，注意windows和linx的换行符不同，导致启动失败，可使用notepad++中编辑-->文档格式转换-->转换成Unix格式。2、注意给脚本设置权限4、测试本地测试是否能够启动启动sentinel服务sh sentinel.sh start停止sentinel服务sh sentinel.sh stop重启sentinel服务sh sentinel.sh restart查看sentinel服务状态sh sentinel.sh status服务启动后，可通过IP+端口+项目名访问Sentinel登录页面5、自启动本地测试可通过命令启动没问题后，编写启动服务sentinel.service，放到/usr/lib/systemd/system目录，内容如下：[Unit] Description=sentinel After=network.target [Service] Environment="JAVA_HOME=/usr/local/java/jdk-11.0.10" Type=forking ExecStart=/usr/local/sentinel/sh/sentinel.sh start ExecReload=/usr/local/sentinel/sh/entinel.sh stop ExecStop=/usr/local/sentinel/sentinel/sh/sentinel.sh restart PrivateTmp=true [Install] WantedBy=multi-user.target重载所有服务systemctl daemon-reload设置开机启动systemctl enable sentinel.service查看开机启动状态systemctl is-enabled sentinel.service查看服务状态systemctl status sentinel手动启动 Sentinelsystemctl start sentinel手动停止Sentinelsystemctl stop sentinel手动重启Sentinelsystemctl restart sentinel6、结果根据启动日志INFO: Sentinel log output type is: file INFO: Sentinel log charset is: utf-8 INFO: Sentinel log base directory is: /root/logs/csp/ INFO: Sentinel log name use pid is: false INFO: Sentinel log level is: INFO . ____ _ __ _ _ /\\ / ___'_ __ _ _(_)_ __ __ _ \ \ \ \ ( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \ \\/ ___)| |_)| | | | | || (_| | ) ) ) ) ' |____| .__|_| |_|_| |_\__, | / / / / =========|_|==============|___/=/_/_/_/ :: Spring Boot :: (v2.5.12) 2022-10-27 15:07:50.068 INFO 733 --- [ main] c.a.c.s.dashboard.DashboardApplication : Starting DashboardApplication using Java 11.0.10 on 10.0.2.15 with PID 733 (/usr/local/sentinel/jar/sentinel-dashboard-1.8.6.jar started by root in /) 2022-10-27 15:07:50.280 INFO 733 --- [ main] c.a.c.s.dashboard.DashboardApplication : No active profile set, falling back to 1 default profile: "default" 2022-10-27 15:08:54.090 INFO 733 --- [ main] o.s.b.w.embedded.tomcat.TomcatWebServer : Tomcat initialized with port(s): 9100 (http) 2022-10-27 15:08:54.616 INFO 733 --- [ main] o.apache.catalina.core.StandardService : Starting service [Tomcat] 2022-10-27 15:08:54.616 INFO 733 --- [ main] org.apache.catalina.core.StandardEngine : Starting Servlet engine: [Apache Tomcat/9.0.60] 2022-10-27 15:08:57.256 INFO 733 --- [ main] o.a.c.c.C.[Tomcat].[localhost].[/] : Initializing Spring embedded WebApplicationContext 2022-10-27 15:08:57.259 INFO 733 --- [ main] w.s.c.ServletWebServerApplicationContext : Root WebApplicationContext: initialization completed in 40159 ms 2022-10-27 15:08:58.193 INFO 733 --- [ main] c.a.c.s.dashboard.config.WebConfig : Sentinel servlet CommonFilter registered 2022-10-27 15:09:04.587 INFO 733 --- [ main] o.s.b.w.embedded.tomcat.TomcatWebServer : Tomcat started on port(s): 9100 (http) with context path '' 2022-10-27 15:09:04.788 INFO 733 --- [ main] c.a.c.s.dashboard.DashboardApplication : Started DashboardApplication in 79.475 seconds (JVM running for 82.322) 2022-10-27 15:09:13.768 INFO 733 --- [nio-9100-exec-3] o.a.c.c.C.[Tomcat].[localhost].[/] : Initializing Spring DispatcherServlet 'dispatcherServlet' 2022-10-27 15:09:13.807 INFO 733 --- [nio-9100-exec-3] o.s.web.servlet.DispatcherServlet : Initializing Servlet 'dispatcherServlet' 2022-10-27 15:09:14.119 INFO 733 --- [nio-9100-exec-3] o.s.web.servlet.DispatcherServlet : Completed initialization in 311 ms启动成功，通过访问IP+端口+项目，成功访问到Sentinel登录页面，账号：sentinel,密码：sentinel

Nacos持久化MySQL问题-解决方案 Nacos持久化MySQL问题-解决方案一、说明环境说明：MySQL：CentOS环境通过Docker部署的MySQL5.7Nacos：2.0.3原始配置：### If use MySQL as datasource: # spring.datasource.platform=mysql ### Count of DB: # db.num=1 ### Connect URL of DB: # db.url.0=jdbc:mysql://127.0.0.1:3306/nacos?characterEncoding=utf8&connectTimeout=1000&socketTimeout=3000&autoReconnect=true&useUnicode=true&useSSL=false&serverTimezone=UTC # db.user.0=nacos # db.password.0=nacos二、问题启动nacos持久化MySQL报错：/usr/local/java/jdk-11.0.10/bin/java -Xms512m -Xmx512m -Xmn256m -Dnacos.standalone=true -Dnacos.member.list= -Xlog:gc*:file=/usr/local/nacos/logs/nacos_gc.log:time,tags:filecount=10,filesize=102400 -Dloader.path=/usr/local/nacos/plugins/health,/usr/local/nacos/plugins/cmdb -Dnacos.home=/usr/local/nacos -jar /usr/local/nacos/target/nacos-server.jar --spring.config.additional-location=file:/usr/local/nacos/conf/ --logging.config=/usr/local/nacos/conf/nacos-logback.xml --server.max-http-header-size=524288 ,--. ,--.'| ,--,: : | Nacos 2.0.3 ,`--.'`| ' : ,---. Running in stand alone mode, All function modules | : : | | ' ,'\ .--.--. Port: 8848 : | \ | : ,--.--. ,---. / / | / / ' Pid: 3180 | : ' '; | / \ / \. ; ,. :| : /`./ Console: http://192.168.56.10:8848/nacos/index.html ' ' ;. ;.--. .-. | / / '' | |: :| : ;_ | | | \ | \__\/: . .. ' / ' | .; : \ \ `. https://nacos.io ' : | ; .' ," .--.; |' ; :__| : | `----. \ | | '`--' / / ,. |' | '.'|\ \ / / /`--' / ' : | ; : .' \ : : `----' '--'. / ; |.' | , .-./\ \ / `--'---' '---' `--`---' `----' 2022-10-26 12:12:21,501 INFO Bean 'org.springframework.security.access.expression.method.DefaultMethodSecurityExpressionHandler@7c8f9c2e' of type [org.springframework.security.access.expression.method.DefaultMethodSecurityExpressionHandler] is not eligible for getting processed by all BeanPostProcessors (for example: not eligible for auto-proxying) 2022-10-26 12:12:21,506 INFO Bean 'methodSecurityMetadataSource' of type [org.springframework.security.access.method.DelegatingMethodSecurityMetadataSource] is not eligible for getting processed by all BeanPostProcessors (for example: not eligible for auto-proxying) 2022-10-26 12:12:21,880 INFO Tomcat initialized with port(s): 8848 (http) 2022-10-26 12:12:22,303 INFO Root WebApplicationContext: initialization completed in 4845 ms 2022-10-26 12:12:34,613 WARN Exception encountered during context initialization - cancelling refresh attempt: org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'memoryMonitor' defined in URL [jar:file:/usr/local/nacos/target/nacos-server.jar!/BOOT-INF/lib/nacos-config-2.0.3.jar!/com/alibaba/nacos/config/server/monitor/MemoryMonitor.class]: Unsatisfied dependency expressed through constructor parameter 0; nested exception is org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'asyncNotifyService': Unsatisfied dependency expressed through field 'dumpService'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'externalDumpService': Invocation of init method failed; nested exception is ErrCode:500, ErrMsg:Nacos Server did not start because dumpservice bean construction failure : No DataSource set 2022-10-26 12:12:34,644 INFO Nacos Log files: /usr/local/nacos/logs 2022-10-26 12:12:34,644 INFO Nacos Log files: /usr/local/nacos/conf 2022-10-26 12:12:34,644 INFO Nacos Log files: /usr/local/nacos/data 2022-10-26 12:12:34,644 ERROR Startup errors : org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'memoryMonitor' defined in URL [jar:file:/usr/local/nacos/target/nacos-server.jar!/BOOT-INF/lib/nacos-config-2.0.3.jar!/com/alibaba/nacos/config/server/monitor/MemoryMonitor.class]: Unsatisfied dependency expressed through constructor parameter 0; nested exception is org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'asyncNotifyService': Unsatisfied dependency expressed through field 'dumpService'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'externalDumpService': Invocation of init method failed; nested exception is ErrCode:500, ErrMsg:Nacos Server did not start because dumpservice bean construction failure : No DataSource set at org.springframework.beans.factory.support.ConstructorResolver.createArgumentArray(ConstructorResolver.java:769) at org.springframework.beans.factory.support.ConstructorResolver.autowireConstructor(ConstructorResolver.java:218) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.autowireConstructor(AbstractAutowireCapableBeanFactory.java:1338) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1185) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:554) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:514) at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:321) at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:234) at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:319) at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:199) at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:866) at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:878) at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:550) at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:141) at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:744) at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:391) at org.springframework.boot.SpringApplication.run(SpringApplication.java:312) at org.springframework.boot.SpringApplication.run(SpringApplication.java:1215) at org.springframework.boot.SpringApplication.run(SpringApplication.java:1204) at com.alibaba.nacos.Nacos.main(Nacos.java:35) at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.base/java.lang.reflect.Method.invoke(Method.java:566) at org.springframework.boot.loader.MainMethodRunner.run(MainMethodRunner.java:49) at org.springframework.boot.loader.Launcher.launch(Launcher.java:108) at org.springframework.boot.loader.Launcher.launch(Launcher.java:58) at org.springframework.boot.loader.PropertiesLauncher.main(PropertiesLauncher.java:467) Caused by: org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'asyncNotifyService': Unsatisfied dependency expressed through field 'dumpService'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'externalDumpService': Invocation of init method failed; nested exception is ErrCode:500, ErrMsg:Nacos Server did not start because dumpservice bean construction failure : No DataSource set at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:598) at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:90) at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessProperties(AutowiredAnnotationBeanPostProcessor.java:376) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1402) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:591) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:514) at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:321) at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:234) at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:319) at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:199) at org.springframework.beans.factory.config.DependencyDescriptor.resolveCandidate(DependencyDescriptor.java:277) at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1276) at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1196) at org.springframework.beans.factory.support.ConstructorResolver.resolveAutowiredArgument(ConstructorResolver.java:857) at org.springframework.beans.factory.support.ConstructorResolver.createArgumentArray(ConstructorResolver.java:760) ... 27 common frames omitted Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'externalDumpService': Invocation of init method failed; nested exception is ErrCode:500, ErrMsg:Nacos Server did not start because dumpservice bean construction failure : No DataSource set at org.springframework.beans.factory.annotation.InitDestroyAnnotationBeanPostProcessor.postProcessBeforeInitialization(InitDestroyAnnotationBeanPostProcessor.java:139) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.applyBeanPostProcessorsBeforeInitialization(AbstractAutowireCapableBeanFactory.java:413) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1761) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:592) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:514) at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:321) at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:234) at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:319) at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:199) at org.springframework.beans.factory.config.DependencyDescriptor.resolveCandidate(DependencyDescriptor.java:277) at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1276) at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1196) at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:595) ... 41 common frames omitted Caused by: com.alibaba.nacos.api.exception.NacosException: Nacos Server did not start because dumpservice bean construction failure : No DataSource set at com.alibaba.nacos.config.server.service.dump.DumpService.dumpOperate(DumpService.java:236) at com.alibaba.nacos.config.server.service.dump.ExternalDumpService.init(ExternalDumpService.java:52) at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.base/java.lang.reflect.Method.invoke(Method.java:566) at org.springframework.beans.factory.annotation.InitDestroyAnnotationBeanPostProcessor$LifecycleElement.invoke(InitDestroyAnnotationBeanPostProcessor.java:363) at org.springframework.beans.factory.annotation.InitDestroyAnnotationBeanPostProcessor$LifecycleMetadata.invokeInitMethods(InitDestroyAnnotationBeanPostProcessor.java:307) at org.springframework.beans.factory.annotation.InitDestroyAnnotationBeanPostProcessor.postProcessBeforeInitialization(InitDestroyAnnotationBeanPostProcessor.java:136) ... 53 common frames omitted Caused by: java.lang.IllegalStateException: No DataSource set at org.springframework.util.Assert.state(Assert.java:73) at org.springframework.jdbc.support.JdbcAccessor.obtainDataSource(JdbcAccessor.java:77) at org.springframework.jdbc.core.JdbcTemplate.execute(JdbcTemplate.java:371) at org.springframework.jdbc.core.JdbcTemplate.query(JdbcTemplate.java:452) at org.springframework.jdbc.core.JdbcTemplate.query(JdbcTemplate.java:462) at org.springframework.jdbc.core.JdbcTemplate.queryForObject(JdbcTemplate.java:473) at org.springframework.jdbc.core.JdbcTemplate.queryForObject(JdbcTemplate.java:480) at com.alibaba.nacos.config.server.service.repository.extrnal.ExternalStoragePersistServiceImpl.findConfigMaxId(ExternalStoragePersistServiceImpl.java:658) at com.alibaba.nacos.config.server.service.dump.processor.DumpAllProcessor.process(DumpAllProcessor.java:51) at com.alibaba.nacos.config.server.service.dump.DumpService.dumpConfigInfo(DumpService.java:293) at com.alibaba.nacos.config.server.service.dump.DumpService.dumpOperate(DumpService.java:205) ... 61 common frames omitted 2022-10-26 12:12:36,322 WARN [WatchFileCenter] start close 2022-10-26 12:12:36,322 WARN [WatchFileCenter] start to shutdown this watcher which is watch : /usr/local/nacos/data/loader 2022-10-26 12:12:36,322 WARN [WatchFileCenter] start to shutdown this watcher which is watch : /usr/local/nacos/conf 2022-10-26 12:12:36,322 WARN [WatchFileCenter] start to shutdown this watcher which is watch : /usr/local/nacos/data/tps 2022-10-26 12:12:36,322 WARN [WatchFileCenter] already closed 2022-10-26 12:12:36,322 WARN [NotifyCenter] Start destroying Publisher 2022-10-26 12:12:36,322 WARN [NotifyCenter] Destruction of the end 2022-10-26 12:12:36,323 ERROR Nacos failed to start, please see /usr/local/nacos/logs/nacos.log for more details. 2022-10-26 12:12:36,345 INFO Error starting ApplicationContext. To display the conditions report re-run your application with 'debug' enabled. 2022-10-26 12:12:36,350 ERROR Application run failed org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'memoryMonitor' defined in URL [jar:file:/usr/local/nacos/target/nacos-server.jar!/BOOT-INF/lib/nacos-config-2.0.3.jar!/com/alibaba/nacos/config/server/monitor/MemoryMonitor.class]: Unsatisfied dependency expressed through constructor parameter 0; nested exception is org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'asyncNotifyService': Unsatisfied dependency expressed through field 'dumpService'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'externalDumpService': Invocation of init method failed; nested exception is ErrCode:500, ErrMsg:Nacos Server did not start because dumpservice bean construction failure : No DataSource set at org.springframework.beans.factory.support.ConstructorResolver.createArgumentArray(ConstructorResolver.java:769) at org.springframework.beans.factory.support.ConstructorResolver.autowireConstructor(ConstructorResolver.java:218) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.autowireConstructor(AbstractAutowireCapableBeanFactory.java:1338) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1185) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:554) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:514) at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:321) at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:234) at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:319) at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:199) at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:866) at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:878) at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:550) at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:141) at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:744) at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:391) at org.springframework.boot.SpringApplication.run(SpringApplication.java:312) at org.springframework.boot.SpringApplication.run(SpringApplication.java:1215) at org.springframework.boot.SpringApplication.run(SpringApplication.java:1204) at com.alibaba.nacos.Nacos.main(Nacos.java:35) at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.base/java.lang.reflect.Method.invoke(Method.java:566) at org.springframework.boot.loader.MainMethodRunner.run(MainMethodRunner.java:49) at org.springframework.boot.loader.Launcher.launch(Launcher.java:108) at org.springframework.boot.loader.Launcher.launch(Launcher.java:58) at org.springframework.boot.loader.PropertiesLauncher.main(PropertiesLauncher.java:467) Caused by: org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'asyncNotifyService': Unsatisfied dependency expressed through field 'dumpService'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'externalDumpService': Invocation of init method failed; nested exception is ErrCode:500, ErrMsg:Nacos Server did not start because dumpservice bean construction failure : No DataSource set at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:598) at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:90) at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessProperties(AutowiredAnnotationBeanPostProcessor.java:376) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1402) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:591) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:514) at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:321) at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:234) at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:319) at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:199) at org.springframework.beans.factory.config.DependencyDescriptor.resolveCandidate(DependencyDescriptor.java:277) at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1276) at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1196) at org.springframework.beans.factory.support.ConstructorResolver.resolveAutowiredArgument(ConstructorResolver.java:857) at org.springframework.beans.factory.support.ConstructorResolver.createArgumentArray(ConstructorResolver.java:760) ... 27 common frames omitted Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'externalDumpService': Invocation of init method failed; nested exception is ErrCode:500, ErrMsg:Nacos Server did not start because dumpservice bean construction failure : No DataSource set at org.springframework.beans.factory.annotation.InitDestroyAnnotationBeanPostProcessor.postProcessBeforeInitialization(InitDestroyAnnotationBeanPostProcessor.java:139) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.applyBeanPostProcessorsBeforeInitialization(AbstractAutowireCapableBeanFactory.java:413) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1761) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:592) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:514) at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:321) at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:234) at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:319) at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:199) at org.springframework.beans.factory.config.DependencyDescriptor.resolveCandidate(DependencyDescriptor.java:277) at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1276) at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1196) at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:595) ... 41 common frames omitted Caused by: com.alibaba.nacos.api.exception.NacosException: Nacos Server did not start because dumpservice bean construction failure : No DataSource set at com.alibaba.nacos.config.server.service.dump.DumpService.dumpOperate(DumpService.java:236) at com.alibaba.nacos.config.server.service.dump.ExternalDumpService.init(ExternalDumpService.java:52) at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.base/java.lang.reflect.Method.invoke(Method.java:566) at org.springframework.beans.factory.annotation.InitDestroyAnnotationBeanPostProcessor$LifecycleElement.invoke(InitDestroyAnnotationBeanPostProcessor.java:363) at org.springframework.beans.factory.annotation.InitDestroyAnnotationBeanPostProcessor$LifecycleMetadata.invokeInitMethods(InitDestroyAnnotationBeanPostProcessor.java:307) at org.springframework.beans.factory.annotation.InitDestroyAnnotationBeanPostProcessor.postProcessBeforeInitialization(InitDestroyAnnotationBeanPostProcessor.java:136) ... 53 common frames omitted Caused by: java.lang.IllegalStateException: No DataSource set at org.springframework.util.Assert.state(Assert.java:73) at org.springframework.jdbc.support.JdbcAccessor.obtainDataSource(JdbcAccessor.java:77) at org.springframework.jdbc.core.JdbcTemplate.execute(JdbcTemplate.java:371) at org.springframework.jdbc.core.JdbcTemplate.query(JdbcTemplate.java:452) at org.springframework.jdbc.core.JdbcTemplate.query(JdbcTemplate.java:462) at org.springframework.jdbc.core.JdbcTemplate.queryForObject(JdbcTemplate.java:473) at org.springframework.jdbc.core.JdbcTemplate.queryForObject(JdbcTemplate.java:480) at com.alibaba.nacos.config.server.service.repository.extrnal.ExternalStoragePersistServiceImpl.findConfigMaxId(ExternalStoragePersistServiceImpl.java:658) at com.alibaba.nacos.config.server.service.dump.processor.DumpAllProcessor.process(DumpAllProcessor.java:51) at com.alibaba.nacos.config.server.service.dump.DumpService.dumpConfigInfo(DumpService.java:293) at com.alibaba.nacos.config.server.service.dump.DumpService.dumpOperate(DumpService.java:205) ... 61 common frames omitted三、参考方案Google到许多解决方案：主要针对application.properties配置文件，数据库配置部分。### If use MySQL as datasource: spring.datasource.platform=mysql ### Count of DB: db.num=1 ### Connect URL of DB: db.url.0=jdbc:mysql://127.0.0.1:3306/nacos_config?characterEncoding=utf8&connectTimeout=1000&socketTimeout=3000&autoReconnect=true&useUnicode=true&useSSL=false&serverTimezone=UTC db.user.0=root db.password.0=root1、检查MySQL账号、密码、IP、端口是否正确。2、数据库连接是否有加时区，serverTimezone=Asia/Shanghai3、数据库版本8.0，需要在nacos下创建plugins/mysql目录，并将mysql-connector-java-8.0.23.jar放入。4、密码有特殊字符的，加单引号。5、查看防火墙端口是否放开或关闭。四、最终解决方案本地问题总结：1、Navicat连接数据库时，连接到了本地，未连接到CentOS系统。因此执行nacos脚本数据库肯定找不到。2、自己创建的数据库为nacos，而实际nacos-mysql.sql 脚本中数据库为nacos_config，因此也找不到。3、application.properties中配置的数据库名称和要和CentOS中创建的数据库名要一样，编码最好也一致。最后启动成功。/usr/local/java/jdk-11.0.10/bin/java -Xms512m -Xmx512m -Xmn256m -Dnacos.standalone=true -Dnacos.member.list= -Xlog:gc*:file=/usr/local/nacos/logs/nacos_gc.log:time,tags:filecount=10,filesize=102400 -Dloader.path=/usr/local/nacos/plugins/health,/usr/local/nacos/plugins/cmdb -Dnacos.home=/usr/local/nacos -jar /usr/local/nacos/target/nacos-server.jar --spring.config.additional-location=file:/usr/local/nacos/conf/ --logging.config=/usr/local/nacos/conf/nacos-logback.xml --server.max-http-header-size=524288 ,--. ,--.'| ,--,: : | Nacos 2.0.3 ,`--.'`| ' : ,---. Running in stand alone mode, All function modules | : : | | ' ,'\ .--.--. Port: 8848 : | \ | : ,--.--. ,---. / / | / / ' Pid: 3408 | : ' '; | / \ / \. ; ,. :| : /`./ Console: http://192.168.56.10:8848/nacos/index.html ' ' ;. ;.--. .-. | / / '' | |: :| : ;_ | | | \ | \__\/: . .. ' / ' | .; : \ \ `. https://nacos.io ' : | ; .' ," .--.; |' ; :__| : | `----. \ | | '`--' / / ,. |' | '.'|\ \ / / /`--' / ' : | ; : .' \ : : `----' '--'. / ; |.' | , .-./\ \ / `--'---' '---' `--`---' `----' 2022-10-26 12:16:14,753 INFO Bean 'org.springframework.security.access.expression.method.DefaultMethodSecurityExpressionHandler@8a2a6a' of type [org.springframework.security.access.expression.method.DefaultMethodSecurityExpressionHandler] is not eligible for getting processed by all BeanPostProcessors (for example: not eligible for auto-proxying) 2022-10-26 12:16:14,763 INFO Bean 'methodSecurityMetadataSource' of type [org.springframework.security.access.method.DelegatingMethodSecurityMetadataSource] is not eligible for getting processed by all BeanPostProcessors (for example: not eligible for auto-proxying) 2022-10-26 12:16:15,308 INFO Tomcat initialized with port(s): 8848 (http) 2022-10-26 12:16:15,818 INFO Root WebApplicationContext: initialization completed in 5099 ms WARNING: An illegal reflective access operation has occurred WARNING: Illegal reflective access by com.alipay.sofa.jraft.util.internal.UnsafeUtil (jar:file:/usr/local/nacos/target/nacos-server.jar!/BOOT-INF/lib/jraft-core-1.3.5.jar!/) to field java.nio.Buffer.address WARNING: Please consider reporting this to the maintainers of com.alipay.sofa.jraft.util.internal.UnsafeUtil WARNING: Use --illegal-access=warn to enable warnings of further illegal reflective access operations WARNING: All illegal access operations will be denied in a future release 2022-10-26 12:16:22,286 INFO Initializing ExecutorService 'applicationTaskExecutor' 2022-10-26 12:16:22,526 INFO Adding welcome page: class path resource [static/index.html] 2022-10-26 12:16:24,101 INFO Creating filter chain: Ant [pattern='/**'], [] 2022-10-26 12:16:24,133 INFO Creating filter chain: any request, [org.springframework.security.web.context.request.async.WebAsyncManagerIntegrationFilter@3313463c, org.springframework.security.web.context.SecurityContextPersistenceFilter@1bfa5a13, org.springframework.security.web.header.HeaderWriterFilter@6eed46e9, org.springframework.security.web.csrf.CsrfFilter@f849027, org.springframework.security.web.authentication.logout.LogoutFilter@76af34b5, org.springframework.security.web.savedrequest.RequestCacheAwareFilter@1da75dde, org.springframework.security.web.servletapi.SecurityContextHolderAwareRequestFilter@595fed99, org.springframework.security.web.authentication.AnonymousAuthenticationFilter@9c0d0bd, org.springframework.security.web.session.SessionManagementFilter@690df641, org.springframework.security.web.access.ExceptionTranslationFilter@6ce9771c] 2022-10-26 12:16:24,276 INFO Initializing ExecutorService 'taskScheduler' 2022-10-26 12:16:24,342 INFO Exposing 16 endpoint(s) beneath base path '/actuator' 2022-10-26 12:16:24,621 INFO Tomcat started on port(s): 8848 (http) with context path '/nacos' 2022-10-26 12:16:24,696 INFO Nacos started successfully in stand alone mode. use embedded storage

CenotOS环境Nacos安装，设置开机自启动 CenotOS环境Nacos安装，设置开机自启动1、下载nacos下载地址：https://github.com/alibaba/nacos/releases2、安装进入nacos所在目录，执行如下命令tar -zxvf nacos-server-2.0.3.tar.gz -C /usr/local/3、单机启动修改/usr/local/nacos/bin目录下startup.sh启动文件设置单机启动，修改export MODE="cluster"值为standaloneexport MODE="standalone"4、启动测试进入/usr/local/nacos/bin目录下，执行启动命令./startup.sh启动失败，查看/usr/local/nacos/logs下start.out日志文件，报错如下：/usr/local/java/jdk-11.0.10/bin/java -Xms512m -Xmx512m -Xmn256m -Dnacos.standalone=true -Dnacos.member.list= -Xlog:gc*:file=/usr/local/nacos/logs/nacos_gc.log:time,tags:filecount=10,filesize=102400 -Dloader.path=/usr/local/nacos/plugins/health,/usr/local/nacos/plugins/cmdb -Dnacos.home=/usr/local/nacos -jar /usr/local/nacos/target/nacos-server.jar --spring.config.additional-location=file:/usr/local/nacos/conf/ --logging.config=/usr/local/nacos/conf/nacos-logback.xml --server.max-http-header-size=524288 Error: Could not find or load main class Caused by: java.lang.ClassNotFoundException: 5、解决方案进入/usr/local/nacos/bin/目录，修改启动文件startup.sh，修改内容如下：x JAVA_OPT_EXT_FIX="-Djava.ext.dirs=${JAVA_HOME}/jre/lib/ext:${JAVA_HOME}/lib/ext" √ JAVA_OPT="${JAVA_OPT} -Djava.ext.dirs=${JAVA_HOME}/jre/lib/ext:${JAVA_HOME}/lib/ext" x echo "$JAVA $JAVA_OPT_EXT_FIX ${JAVA_OPT}" √ echo "$JAVA ${JAVA_OPT}" x echo "$JAVA $JAVA_OPT_EXT_FIX ${JAVA_OPT}" > ${BASE_DIR}/logs/start.out 2>&1 & x nohup "$JAVA" "$JAVA_OPT_EXT_FIX" ${JAVA_OPT} nacos.nacos >> ${BASE_DIR}/logs/start.out 2>&1 & √ echo "$JAVA ${JAVA_OPT}" > ${BASE_DIR}/logs/start.out 2>&1 & √ nohup $JAVA ${JAVA_OPT} nacos.nacos >> ${BASE_DIR}/logs/start.out 2>&1 &x：表示需要替换的，√：表示修改后的。6、再次测试进入/usr/local/nacos/bin目录下，执行启动命令./startup.sh输出结果：/usr/local/java/jdk-11.0.10/bin/java -Xms512m -Xmx512m -Xmn256m -Dnacos.standalone=true -Dnacos.member.list= -Xlog:gc*:file=/usr/local/nacos/logs/nacos_gc.log:time,tags:filecount=10,filesize=102400 -Dloader.path=/usr/local/nacos/plugins/health,/usr/local/nacos/plugins/cmdb -Dnacos.home=/usr/local/nacos -jar /usr/local/nacos/target/nacos-server.jar --spring.config.additional-location=file:/usr/local/nacos/conf/ --logging.config=/usr/local/nacos/conf/nacos-logback.xml --server.max-http-header-size=524288 nacos is starting with standalone nacos is starting，you can check the /usr/local/nacos/logs/start.out表示之前启动问题解决，启动成功。7、访问nacos打开浏览器输入CentOS地址+端口+项目访问，即可看到nacos登录页面。http://192.168.56.10:8848/nacos8、随机启动配置8.1、进入 /lib/systemd/system目录cd /lib/systemd/system8.2、在该目录下，创建文件nacos启动文件vi nacos.service添加内容如下[Unit] Description=nacos After=network.target [Service] Environment="JAVA_HOME=/usr/local/java/jdk-11.0.10" Type=forking ExecStart=/usr/local/nacos/bin/startup.sh -m standalone ExecReload=/usr/local/nacos/bin/shutdown.sh ExecStop=/usr/local/nacos/nacos/bin/shutdown.sh PrivateTmp=true [Install] WantedBy=multi-user.target注意：修改自己nacos所在路径8.3、重载所有服务systemctl daemon-reload8.4、设置开机启动systemctl enable nacos.service8.5、查看开机启动状态systemctl is-enabled nacos.service8.6、查看服务状态systemctl status nacos8.7、手动启动 Nacossystemctl start nacos8.7、手动停止Nacossystemctl stop nacos8.8、手动重启systemctl restart nacos9、测试自启动重启CentOS系统，查看Nacos是否自自动查看Nacos服务状态systemctl status nacos输出结果：● nacos.service - nacos Loaded: loaded (/usr/lib/systemd/system/nacos.service; enabled; vendor preset: disabled) Active: active (running) since Mon 2022-10-24 15:15:16 UTC; 1min 7s ago Process: 707 ExecStart=/usr/local/nacos/bin/startup.sh -m standalone (code=exited, status=0/SUCCESS) Tasks: 194 Memory: 547.8M CGroup: /system.slice/nacos.service └─748 /usr/local/java/jdk-11.0.10/bin/java -Xms512m -Xmx512m -Xmn256m -Dnacos.standalone=true -Dnacos.member.list= -Xlog:gc*:file=/usr/local/nacos/logs/nacos_gc.log:time,tag... Oct 24 15:15:15 10.0.2.15 systemd[1]: Starting nacos... Oct 24 15:15:16 10.0.2.15 startup.sh[707]: /usr/local/java/jdk-11.0.10/bin/java -Xms512m -Xmx512m -Xmn256m -Dnacos.standalone=true -Dnacos.member.list= -Xlog:gc*:file=/usr...s.home=/usr/ Oct 24 15:15:16 10.0.2.15 startup.sh[707]: nacos is starting with standalone Oct 24 15:15:16 10.0.2.15 startup.sh[707]: nacos is starting，you can check the /usr/local/nacos/logs/start.out Oct 24 15:15:16 10.0.2.15 systemd[1]: Started nacos. Hint: Some lines were ellipsized, use -l to show in full.表示已经启动成功。通过IP+端口+项目访问登录页面测试http://192.168.56.10:8848/nacos已经可以成功访问Nacos登录页面了。

CentOS环境JDK11安装 CentOS环境JDK安装1、下载JDK11下载地址：https://www.oracle.com/java/technologies/javase/jdk11-archive-downloads.html2、路径创建jdk安装文件夹mkdir /usr/local/java3、安装进入下载的jdk所在目录，执行安装命令。tar -zxvf jdk-11.0.10_linux-x64_bin.tar.gz -C /usr/local/java/4、环境配置修改系统环境文件/etc/profile，在最后加上java环境变量配置信息。export JAVA_HOME=/usr/local/java/jdk-11.0.10 export JRE_HOME=${JAVA_HOME}/jre export CLASSPATH=.:${JAVA_HOME}/lib:${JRE_HOME}/lib export PATH=${JAVA_HOME}/bin:$PATH5、连接创建软连接ln -s /usr/local/java/jdk-11.0.10/bin/java /usr/bin/java6、验证java -version输出结果：java version "11.0.10" 2021-01-19 LTS Java(TM) SE Runtime Environment 18.9 (build 11.0.10+8-LTS-162) Java HotSpot(TM) 64-Bit Server VM 18.9 (build 11.0.10+8-LTS-162, mixed mode)

JAVA8-自定义Spliterator JAVA8-自定义Spliterator需求说明：将一段话按换行符分割成多个执行，并输出。package com.example.study.java8.forkjoin; import java.util.Objects; import java.util.Spliterator; import java.util.function.Consumer; import java.util.stream.Stream; import java.util.stream.StreamSupport; /** * 自定义Spliterator * 实列：将一段话按换行符分割成多个执行，并输出。 */ public class SpliteratorInAction { //需要处理的数据 private static String text = "The tryAdvance method feeds the Consumer with the Character in the String at the current index\n" + "position and increments this position. The Consumer passed as argument is an internal Java class\n" + "forwarding the consumed Character to the set of functions that have to be applied to it while\n" + "traversing the stream, which in this case is only a reducing function, namely, the accumulate method\n" + "of the WordCounter class. The tryAdvance method returns true if the new cursor position is less\n" + "than the total String length and there are further Characters to be iterated.\n" + "\uF0B7 The trySplit method is the most important one in a Spliterator because it’s the one defining the\n" + "logic used to split the data structure to be iterated. As you did in the compute method of the\n" + "RecursiveTask implemented in listing 7.1 (on how to use the fork/join framework), the first thing\n" + "you have to do here is set a limit under which you don’t want to perform further splits. Here, you use a\n" + "very low limit of 10 Characters only to make sure that your program will perform some splits with\n" + "the relatively short String you’re parsing, but in real-world applications you’ll have to use a higher\n" + "limit, as you did in the fork/join example, to avoid creating too many tasks. If the number of\n" + "remaining Characters to be traversed is under this limit, you return null to signal that no further\n" + "split is necessary. Conversely, if you need to perform a split, you set the candidate split position to the\n" + "half of the String chunk remaining to be parsed. But you don’t use this split position directly because\n" + "www.it-ebooks.info\n" + "231\n" + "you want to avoid splitting in the middle of a word, so you move forward until you find a blank\n" + "Character. Once you find an opportune split position, you create a new Spliterator that will traverse\n" + "the substring chunk going from the current position to the split one; you set the current position of\n" + "this to the split one, because the part before it will be managed by the new Spliterator, and then you\n" + "return it.\n" + "\uF0B7 The estimatedSize of elements still to be traversed is the difference between the total length of the\n" + "String parsed by this Spliterator and the position currently iterated.\n" + "\uF0B7 Finally, the characteristic method signals to the framework that this Spliterator is ORDERED\n" + "(the order is just the sequence of Characters in the String), SIZED (the value returned by the\n" + "estimatedSize method is exact), SUBSIZED (the other Spliterators created by the trySplit\n" + "method also have an exact size), NONNULL (there can be no null Characters in the String), and\n" + "IMMUTABLE (no further Characters can be added while parsing the String because the String\n" + "itself is an immutable class)."; public static void main(String[] args) { //测试 // IntStream intStream = IntStream.rangeClosed(1, 10); // Spliterator.OfInt spliterator = intStream.spliterator(); // Consumer<Integer> integerConsumer = i-> System.out.println(i); // spliterator.forEachRemaining(integerConsumer); MySpliteratorText mySpliteratorText = new MySpliteratorText(text); //串行调用 // Optional.ofNullable(mySpliteratorText.stream().count()) // .ifPresent(System.out::println); // mySpliteratorText.stream().forEach(System.out::println); //并行执行 mySpliteratorText.stream().filter(s -> !"".equals(s)).forEach(System.out::println); mySpliteratorText.parallelStream().filter(s -> !"".equals(s)).forEach(System.out::println); } /** * 自定义Spliterator */ static class MySpliteratorText { private final String[] data; public MySpliteratorText(String text) { Objects.requireNonNull(text, "Ths parameter can not be null"); this.data = text.split("\n"); } //暴露使用方法,穿行 public Stream<String> stream() { return StreamSupport.stream(new MySpliterator(), false); } //暴露使用方法,并行 public Stream<String> parallelStream() { return StreamSupport.stream(new MySpliterator(), true); } private class MySpliterator implements Spliterator<String> { private int start, end; public MySpliterator() { this.start = 0; this.end = MySpliteratorText.this.data.length - 1; } public MySpliterator(int start, int end) { this.start = start; this.end = end; } /** * 不管串行还是并行都会执行，有数据就进行Consumer,没有就返回false； * * @param action * @return */ @Override public boolean tryAdvance(Consumer<? super String> action) { //元素是有的,就进行消费 if (start <= end) { action.accept(MySpliteratorText.this.data[start++]); return true; } return false; } @Override public Spliterator<String> trySplit() { int mid = (end - start) / 2; //没有可拆的 if (mid <= 1) { return null; } int left = start; int right = start + mid; start = start + mid + 1; return new MySpliterator(left, right); } @Override public long estimateSize() { return end - start; } @Override public long getExactSizeIfKnown() { return estimateSize(); } @Override public int characteristics() { return IMMUTABLE | SIZED | SUBSIZED; } } } } 串行调用输出结果：The tryAdvance method feeds the Consumer with the Character in the String at the current index position and increments this position. The Consumer passed as argument is an internal Java class forwarding the consumed Character to the set of functions that have to be applied to it while traversing the stream, which in this case is only a reducing function, namely, the accumulate method of the WordCounter class. The tryAdvance method returns true if the new cursor position is less than the total String length and there are further Characters to be iterated.  The trySplit method is the most important one in a Spliterator because it’s the one defining the logic used to split the data structure to be iterated. As you did in the compute method of the RecursiveTask implemented in listing 7.1 (on how to use the fork/join framework), the first thing you have to do here is set a limit under which you don’t want to perform further splits. Here, you use a very low limit of 10 Characters only to make sure that your program will perform some splits with the relatively short String you’re parsing, but in real-world applications you’ll have to use a higher limit, as you did in the fork/join example, to avoid creating too many tasks. If the number of remaining Characters to be traversed is under this limit, you return null to signal that no further split is necessary. Conversely, if you need to perform a split, you set the candidate split position to the half of the String chunk remaining to be parsed. But you don’t use this split position directly because www.it-ebooks.info 231 you want to avoid splitting in the middle of a word, so you move forward until you find a blank Character. Once you find an opportune split position, you create a new Spliterator that will traverse the substring chunk going from the current position to the split one; you set the current position of this to the split one, because the part before it will be managed by the new Spliterator, and then you return it.  The estimatedSize of elements still to be traversed is the difference between the total length of the String parsed by this Spliterator and the position currently iterated.  Finally, the characteristic method signals to the framework that this Spliterator is ORDERED (the order is just the sequence of Characters in the String), SIZED (the value returned by the estimatedSize method is exact), SUBSIZED (the other Spliterators created by the trySplit method also have an exact size), NONNULL (there can be no null Characters in the String), and IMMUTABLE (no further Characters can be added while parsing the String because the String itself is an immutable class).并行调用输出结果：The tryAdvance method feeds the Consumer with the Character in the String at the current index position and increments this position. The Consumer passed as argument is an internal Java class forwarding the consumed Character to the set of functions that have to be applied to it while traversing the stream, which in this case is only a reducing function, namely, the accumulate method of the WordCounter class. The tryAdvance method returns true if the new cursor position is less than the total String length and there are further Characters to be iterated.  The trySplit method is the most important one in a Spliterator because it’s the one defining the logic used to split the data structure to be iterated. As you did in the compute method of the RecursiveTask implemented in listing 7.1 (on how to use the fork/join framework), the first thing you have to do here is set a limit under which you don’t want to perform further splits. Here, you use a very low limit of 10 Characters only to make sure that your program will perform some splits with the relatively short String you’re parsing, but in real-world applications you’ll have to use a higher limit, as you did in the fork/join example, to avoid creating too many tasks. If the number of remaining Characters to be traversed is under this limit, you return null to signal that no further split is necessary. Conversely, if you need to perform a split, you set the candidate split position to the half of the String chunk remaining to be parsed. But you don’t use this split position directly because www.it-ebooks.info 231 you want to avoid splitting in the middle of a word, so you move forward until you find a blank Character. Once you find an opportune split position, you create a new Spliterator that will traverse the substring chunk going from the current position to the split one; you set the current position of this to the split one, because the part before it will be managed by the new Spliterator, and then you return it.  The estimatedSize of elements still to be traversed is the difference between the total length of the String parsed by this Spliterator and the position currently iterated.  Finally, the characteristic method signals to the framework that this Spliterator is ORDERED (the order is just the sequence of Characters in the String), SIZED (the value returned by the estimatedSize method is exact), SUBSIZED (the other Spliterators created by the trySplit method also have an exact size), NONNULL (there can be no null Characters in the String), and IMMUTABLE (no further Characters can be added while parsing the String because the String itself is an immutable class). the substring chunk going from the current position to the split one; you set the current position of this to the split one, because the part before it will be managed by the new Spliterator, and then you return it.  The estimatedSize of elements still to be traversed is the difference between the total length of the www.it-ebooks.info 231 you want to avoid splitting in the middle of a word, so you move forward until you find a blank Character. Once you find an opportune split position, you create a new Spliterator that will traverse method also have an exact size), NONNULL (there can be no null Characters in the String), and IMMUTABLE (no further Characters can be added while parsing the String because the String itself is an immutable class). String parsed by this Spliterator and the position currently iterated.  Finally, the characteristic method signals to the framework that this Spliterator is ORDERED (the order is just the sequence of Characters in the String), SIZED (the value returned by the estimatedSize method is exact), SUBSIZED (the other Spliterators created by the trySplit of the WordCounter class. The tryAdvance method returns true if the new cursor position is less than the total String length and there are further Characters to be iterated.  The trySplit method is the most important one in a Spliterator because it’s the one defining the logic used to split the data structure to be iterated. As you did in the compute method of the The tryAdvance method feeds the Consumer with the Character in the String at the current index limit, as you did in the fork/join example, to avoid creating too many tasks. If the number of remaining Characters to be traversed is under this limit, you return null to signal that no further split is necessary. Conversely, if you need to perform a split, you set the candidate split position to the half of the String chunk remaining to be parsed. But you don’t use this split position directly because RecursiveTask implemented in listing 7.1 (on how to use the fork/join framework), the first thing you have to do here is set a limit under which you don’t want to perform further splits. Here, you use a very low limit of 10 Characters only to make sure that your program will perform some splits with the relatively short String you’re parsing, but in real-world applications you’ll have to use a higher position and increments this position. The Consumer passed as argument is an internal Java class forwarding the consumed Character to the set of functions that have to be applied to it while traversing the stream, which in this case is only a reducing function, namely, the accumulate method Disconnected from the target VM, address: '127.0.0.1:2490', transport: 'socket'说明：//测试 IntStream intStream = IntStream.rangeClosed(1, 10); Spliterator.OfInt spliterator = intStream.spliterator(); Consumer<Integer> integerConsumer = i-> System.out.println(i); spliterator.forEachRemaining(integerConsumer);Spliterator.OfInt其实就是Spliterator的子类，源码：public interface OfInt extends OfPrimitive<Integer, IntConsumer, OfInt> { }

JAVA8-Fork Join JAVA8-Fork JoinFork：将一个任务拆分成多个线程执行。Join：将每个现场结果join，最后得到结果。范例：求数组总和前置数据：public static int[] data = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10};1、原始实现方式 public static int calc() { int result = 0; for (int i = 0; i < data.length; i++) { result += data[i]; } return result; }原始实现方式调用：System.out.println("result=> " + calc());2、RecursiveTask实现RecursiveTask有返回值。package com.example.study.java8.forkjoin; import lombok.AllArgsConstructor; import lombok.Data; import lombok.NoArgsConstructor; import lombok.ToString; import java.util.concurrent.RecursiveTask; @Data @AllArgsConstructor @NoArgsConstructor @ToString public class AccumulatorRecursiveTask extends RecursiveTask<Integer> { private int start; private int end; private int[] data; private int LIMIT=3; public AccumulatorRecursiveTask(int start, int end, int[] data) { this.start = start; this.end = end; this.data = data; } @Override protected Integer compute() { //如果小于3个就可以直接进行计算了，否则fork成多个，再计算 if(end -start <LIMIT) { int result =0; for(int i=start;i<end;i++){ result+=data[i]; } return result; } int mid = (start+end)/2; AccumulatorRecursiveTask left = new AccumulatorRecursiveTask(start,mid,data); AccumulatorRecursiveTask right = new AccumulatorRecursiveTask(mid,end,data); left.fork(); Integer rightResult = right.compute(); Integer leftResult = left.join(); return rightResult+leftResult; } } RecursiveTask调用： AccumulatorRecursiveTask task = new AccumulatorRecursiveTask(0, data.length, data); ForkJoinPool forkJoinPool = new ForkJoinPool(); Integer result = forkJoinPool.invoke(task); System.out.println("AccumulatorRecursiveTask result => " + result);3、RecursiveAction实现RecursiveAction:无返回值package com.example.study.java8.forkjoin; import lombok.AllArgsConstructor; import lombok.Data; import lombok.NoArgsConstructor; import lombok.ToString; import java.util.concurrent.RecursiveAction; import java.util.concurrent.atomic.AtomicInteger; @Data @AllArgsConstructor @NoArgsConstructor @ToString public class AccumulatorRecursiveAction extends RecursiveAction { private int start; private int end; private int[] data; private int LIMIT = 3; public AccumulatorRecursiveAction(int start, int end, int[] data) { this.start = start; this.end = end; this.data = data; } @Override protected void compute() { //如果小于3个就可以直接进行计算了，否则fork成多个，再计算 if (end - start < LIMIT) { for (int i = start; i < end; i++) { AccumulatorHelper.accumulate(data[i]); } } else { int mid = (start + end) / 2; AccumulatorRecursiveAction left = new AccumulatorRecursiveAction(start, mid, data); AccumulatorRecursiveAction right = new AccumulatorRecursiveAction(mid, end, data); right.fork(); left.fork(); right.join(); left.join(); } } static class AccumulatorHelper { private static final AtomicInteger result = new AtomicInteger(0); static void accumulate(int value) { result.getAndAdd(value); } public static int getResult() { return result.get(); } static void rest() { result.set(0); } } } RecursiveAction调用： AccumulatorRecursiveAction action = new AccumulatorRecursiveAction(0, data.length, data); forkJoinPool.invoke(action); System.out.println("AccumulatorRecursiveAction result => " + AccumulatorRecursiveAction.AccumulatorHelper.getResult());最后输出结果result=> 55 AccumulatorRecursiveTask result => 55 AccumulatorRecursiveAction result => 55

JAVA8-Stream parallel 并行执行 Stream parallel 并行执行范例：求1~100000000的和，执行10次，看时间效率。代码package com.example.study.java8.collector; import java.util.function.Function; import java.util.stream.LongStream; import java.util.stream.Stream; /** * Stream parallel并行执行 * 实列：求10次，1~100000000的和，看时间效率。 */ public class ParallelProcessing { public static void main(String[] args) { //获取电脑CPU核数 System.out.println("当前电脑CPU核数= " + Runtime.getRuntime().availableProcessors()); System.out.println("The best process time(normalAdd)=> " + measureSumPerformance(ParallelProcessing::normalAdd, 100_000_000) + " MS"); System.out.println("The best process time(iterateStream1)=> " + measureSumPerformance(ParallelProcessing::iterateStream1, 100_000_000) + " MS"); System.out.println("The best process time(iterateStream2)=> " + measureSumPerformance(ParallelProcessing::iterateStream2, 100_000_000) + " MS"); System.out.println("The best process time(iterateStream3)=> " + measureSumPerformance(ParallelProcessing::iterateStream3, 100_000_000) + " MS"); System.out.println("The best process time(iterateStream4)=> " + measureSumPerformance(ParallelProcessing::iterateStream4, 100_000_000) + " MS"); System.out.println("The best process time(iterateStream5)=> " + measureSumPerformance(ParallelProcessing::iterateStream5, 100_000_000) + " MS"); } private static long measureSumPerformance(Function<Long, Long> adder, long limist) { long fastest = Long.MAX_VALUE; for (int i = 0; i < 10; i++) { Long startTimestamp = System.currentTimeMillis(); long result = adder.apply(limist); long duration = System.currentTimeMillis() - startTimestamp; // System.out.println("The result of sum=>"+result); if (duration < fastest) fastest = duration; } return fastest; } /** * 1、函数式编程实现：没有使用并行执行 * * @param limit * @return */ public static long iterateStream1(long limit) { return Stream.iterate(1L, i -> i + 1).limit(limit).reduce(0L, Long::sum); } /** * 2、函数式编程实现-进化：使用并行执行，要进行拆箱装箱 * * @param limit * @return */ public static long iterateStream2(long limit) { return Stream.iterate(1L, i -> i + 1).parallel().limit(limit).reduce(0L, Long::sum); } /** * 3、函数式编程实现-再次进化：只用并行执行，不进行拆箱装箱 * * @param limit * @return */ public static long iterateStream3(long limit) { return Stream.iterate(1L, i -> i + 1).mapToLong(Long::longValue).parallel().limit(limit).reduce(0L, Long::sum); } /** * 4、函数式编程实现-再次再次进化：只用并行执行 * * @param limit * @return */ public static long iterateStream4(long limit) { return LongStream.rangeClosed(1L, limit).parallel().sum(); } /** * 5、函数式编程实现-再次再次再次进化 * * @param limit * @return */ public static long iterateStream5(long limit) { return LongStream.rangeClosed(1L, limit).parallel().reduce(0L, Long::sum); } /** * 原始写法 * * @param limit * @return */ public static long normalAdd(long limit) { long result = 0L; for (long i = 1; i < limit; i++) { result++; } return result; } } 输出结果当前电脑CPU核数= 16 The best process time(normalAdd)=> 29 MS The best process time(iterateStream1)=> 794 MS The best process time(iterateStream2)=> 2718 MS The best process time(iterateStream3)=> 2132 MS The best process time(iterateStream4)=> 6 MS The best process time(iterateStream5)=> 24 MS4和5效率差不多输出结果：当前电脑CPU核数= 16 The best process time(normalAdd)=> 29 MS The best process time(iterateStream4)=> 4 MS The best process time(iterateStream5)=> 5 MS结果可以看到使用LongStream的parallel并发执行效率最高。使用注意点Source DecomposabilityArrayList Excellent( 极好的)LinkedList Poor(不好的)IntStream.range Excellent( 极好的)Stream.iterate Poor(不好的)HashSet Good(好的)TreeSet Good(好的)上面的例子就是使用的LongStream.rangeClosed（），就是IntStream.range效率Excellent( 极好的)。

JAVA8-自定义Collector 自定义Collector实现Collector接口package com.example.study.java8.collector; import java.util.*; import java.util.function.BiConsumer; import java.util.function.BinaryOperator; import java.util.function.Function; import java.util.function.Supplier; import java.util.stream.Collector; /** * 自定义Collector * T:元素类型 * List<T>:要创建的类型 * List<T>:最后要返回的类型 */ public class ToListCollector<T> implements Collector<T, List<T>, List<T>> { private void log(final String log) { System.out.println(Thread.currentThread().getName()+"-"+log); } //一定时可变的supplier，不是固定值 @Override public Supplier<List<T>> supplier() { log("supplier"); return ArrayList::new; } //要进行的操作 @Override public BiConsumer<List<T>, T> accumulator() { log("accumulator"); return List::add; } //将结果整合 @Override public BinaryOperator<List<T>> combiner() { log("combiner"); return (list1,list2)->{ list1.addAll(list2); return list1; }; } //返回结果 @Override public Function<List<T>, List<T>> finisher() { log("finisher"); // return t->t; return Function.identity(); } //特征值:CONCURRENT-并行,UNORDERED-排序，IDENTITY_FINISH-入参就出参 @Override public Set<Characteristics> characteristics() { log("characteristics"); return Collections.unmodifiableSet(EnumSet.of(Characteristics.IDENTITY_FINISH, Characteristics.CONCURRENT)); } } 使用测试package com.example.study.java8.collector; import java.util.Arrays; import java.util.List; import java.util.stream.Collector; /** * 使用自定义Collector测试 */ public class CustomToListCollector { public static void main(String[] args) { String[] arrs = new String[]{"chinese","japanse","english","freach","Korean"}; //测试 //对应接口中的： //Supplier<A> supplier(), BiConsumer<A, T> accumulator(),Function<A, R> finisher(); Collector<String, List<String>, List<String>> collector = new ToListCollector<String>(); List<String> list = Arrays.stream(arrs).filter(s -> s.length() > 6).collect(collector); System.out.println(list); System.out.println("================================"); //parallelStream（），并行使用测试 List<String> parallelList = Arrays.asList(new String[]{"chinese", "japanse", "english", "freach", "Korean"}) .parallelStream() .filter(s -> s.length() > 6) .collect(collector); System.out.println(parallelList); } } 输出结果main-supplier main-accumulator main-combiner main-characteristics main-characteristics [chinese, japanse, english] ================================ main-characteristics main-characteristics main-supplier main-accumulator main-combiner main-characteristics main-characteristics [chinese, japanse, english]由于数据量少，并没有出现并行。