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1.tomcat9中报错
... 37 more
Caused by: org.springframework.jmx.export.UnableToRegisterMBeanException: Unable to register MBean [com.alibaba.druid.filter.stat.StatFilter@1dbef693] with key 'statFilter'; nested exception is javax.management.InstanceAlreadyExistsException: com.alibaba.druid.filter.stat:name=statFilter,type=StatFilter
at org.springframework.jmx.export.MBeanExporter.registerBeanNameOrInstance(MBeanExporter.java:628)
at org.springframework.jmx.export.MBeanExporter.registerBeans(MBeanExporter.java:550)
at org.springframework.jmx.export.MBeanExporter.afterSingletonsInstantiated(MBeanExporter.java:432)
at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:781)
at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:866)
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:542)
at org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.refresh(EmbeddedWebApplicationContext.java:122)
at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:737)
at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:370)
at org.springframework.boot.SpringApplication.run(SpringApplication.java:314)
at org.springframework.boot.web.support.SpringBootServletInitializer.run(SpringBootServletInitializer.java:151)
at org.springframework.boot.web.support.SpringBootServletInitializer.createRootApplicationContext(SpringBootServletInitializer.java:131)
at org.springframework.boot.web.support.SpringBootServletInitializer.onStartup(SpringBootServletInitializer.java:86)
at org.springframework.web.SpringServletContainerInitializer.onStartup(SpringServletContainerInitializer.java:169)
at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5139)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183)
... 38 more
Caused by: javax.management.InstanceAlreadyExistsException: com.alibaba.druid.filter.stat:name=statFilter,type=StatFilter
at com.sun.jmx.mbeanserver.Repository.addMBean(Repository.java:437)
at com.sun.jmx.interceptor.DefaultMBeanServerInterceptor.registerWithRepository(DefaultMBeanServerInterceptor.java:1898)
at com.sun.jmx.interceptor.DefaultMBeanServerInterceptor.registerDynamicMBean(DefaultMBeanServerInterceptor.java:966)
at com.sun.jmx.interceptor.DefaultMBeanServerInterceptor.registerObject(DefaultMBeanServerInterceptor.java:900)
at com.sun.jmx.interceptor.DefaultMBeanServerInterceptor.registerMBean(DefaultMBeanServerInterceptor.java:324)
at com.sun.jmx.mbeanserver.JmxMBeanServer.registerMBean(JmxMBeanServer.java:522)
at org.springframework.jmx.support.MBeanRegistrationSupport.doRegister(MBeanRegistrationSupport.java:195)
at org.springframework.jmx.export.MBeanExporter.registerBeanInstance(MBeanExporter.java:674)
at org.springframework.jmx.export.MBeanExporter.registerBeanNameOrInstance(MBeanExporter.java:618)
... 53 more
2.解决
首先看报错说的是InstanceAlreadyExistsException，也就是StatFilter（Druid内置用于统计监控信息的）实例已经起了，在启动报重复异常。
一开始想的是重启tomcat但是之前的进程没关闭，然而ps -ef|grep tomcat 后发现就一个tomcat起着。
然后查看启动日志：
发现启动日志很长，而且有两次初始连接池的情况，理所当然报错了
然后想到之前对tomcat的server.xml进行了修改：
因为注册了一个域名，但是又想直接域名就能访问到项目主页，又不想通过代理转发的方式，所以修改了server.xml
一开始是这样配置的：
<Host name="www.cthlizi.cn" appBase="webapps"
unpackWARs="true" autoDeploy="true">
<Context docBase="gmweb" path="" reloadable="false" />
这边的appBase="webapps"会导致tomcat加载一次应用，然后有配置了Context ，其中docBase又会导致加载一次应用
所以需要修改这里的配置，参照上面大图
最后再次重启tomcat发现没有异常了，也不影响我的要求。
ps:http://www.cthlizi.cn/ 准备弄个人网站，慢慢搭建中…