一、問題來源

  今天在部署開發好的元件的時候，發現無法啟動，檢查啟動日誌，報如下錯誤：

2022-03-17T10:39:41.823+08:00 ERROR vediomanage.vediomanage [localhost-startStop-5] [org.springframework.boot.SpringApplication:823] - Application run failed
org.springframework.jmx.export.UnableToRegisterMBeanException: Unable to register MBean [org.springframework.cloud.context.environment.EnvironmentManager@1c68757b] with key 
 
'environmentManager'; nested exception is javax.management.InstanceAlreadyExistsException: org.springframework.cloud.context.environment:name=environmentManager,type=EnvironmentManager
        at org.springframework.jmx.export.MBeanExporter.registerBeanNameOrInstance(MBeanExporter.java:625)
        at org.springframework.jmx.export.MBeanExporter.lambda$registerBeans$
 
2(MBeanExporter.java:551)
        at java.base/java.util.HashMap.forEach(HashMap.java:1336)
        at org.springframework.jmx.export.MBeanExporter.registerBeans(MBeanExporter.java:551)
        at org.springframework.jmx.export.MBeanExporter.afterSingletonsInstantiated(MBeanExporter.java:434)
        at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:
 
863)
        at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:863)
        at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:546)
        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.web.servlet.support.SpringBootServletInitializer.run(SpringBootServletInitializer.java:151)
        at org.springframework.boot.web.servlet.support.SpringBootServletInitializer.createRootApplicationContext(SpringBootServletInitializer.java:131)
        at org.springframework.boot.web.servlet.support.SpringBootServletInitializer.onStartup(SpringBootServletInitializer.java:91)
        at org.springframework.web.SpringServletContainerInitializer.onStartup(SpringServletContainerInitializer.java:171)
        at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5225)
        at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
        at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:754)
        at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:730)
        at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:744)
        at org.apache.catalina.startup.HostConfig.deployDirectory(HostConfig.java:1135)
        at org.apache.catalina.startup.HostConfig$DeployDirectory.run(HostConfig.java:1869)
        at java.base/java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:515)
        at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264)
        at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
        at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
        at java.base/java.lang.Thread.run(Thread.java:834)
Caused by: javax.management.InstanceAlreadyExistsException: org.springframework.cloud.context.environment:name=environmentManager,type=EnvironmentManager
        at java.management/com.sun.jmx.mbeanserver.Repository.addMBean(Repository.java:436)
        at java.management/com.sun.jmx.interceptor.DefaultMBeanServerInterceptor.registerWithRepository(DefaultMBeanServerInterceptor.java:1855)
        at java.management/com.sun.jmx.interceptor.DefaultMBeanServerInterceptor.registerDynamicMBean(DefaultMBeanServerInterceptor.java:955)
        at java.management/com.sun.jmx.interceptor.DefaultMBeanServerInterceptor.registerObject(DefaultMBeanServerInterceptor.java:890)
        at java.management/com.sun.jmx.interceptor.DefaultMBeanServerInterceptor.registerMBean(DefaultMBeanServerInterceptor.java:320)
        at java.management/com.sun.jmx.mbeanserver.JmxMBeanServer.registerMBean(JmxMBeanServer.java:522)
        at org.springframework.jmx.support.MBeanRegistrationSupport.doRegister(MBeanRegistrationSupport.java:137)
        at org.springframework.jmx.export.MBeanExporter.registerBeanInstance(MBeanExporter.java:679)
        at org.springframework.jmx.export.MBeanExporter.registerBeanNameOrInstance(MBeanExporter.java:615)
        ... 27 common frames omitted

二、解決方法

  application.properties中新增配置：

spring.jmx.default-domain=vediomanage

問題解決。

三、總結

  JMX即Java Management Extension(Java管理應用擴充套件)，這種機制可以方便的管理、監控正在執行的Java程式。常用於監控管理執行緒、記憶體、日誌Level、服務重啟、系統環境等等。springboot中spring.jmx是預設開啟的，要求每個JMX域名字必須是唯一的，當兩個服務同時部署在同一個tomcat上時，由於都沒有指定JMX的域名稱，所以會啟動報錯。