SpringMVC-FAQ（1）：HTTP Status 500

（1）：看Log

type Exception report

message Servlet.init() for servlet DispatcherServlet threw exception

description The server encountered an internal error that prevented it from fulfilling this request.

exception

javax.servlet.ServletException: Servlet.init() for servlet DispatcherServlet threw exceptionorg.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:504)org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79)org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:620)org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:502)org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1132)org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:684)org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1539)org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1495)java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)java.lang.Thread.run(Unknown Source)

root cause

java.security.AccessControlException: access denied ("java.lang.RuntimePermission" "accessDeclaredMembers")java.security.AccessControlContext.checkPermission(Unknown Source)java.security.AccessController.checkPermission(Unknown Source)java.lang.SecurityManager.checkPermission(Unknown Source)java.lang.Class.checkMemberAccess(Unknown Source)java.lang.Class.getDeclaredMethods(Unknown Source)org.springframework.util.ReflectionUtils.getDeclaredMethods(ReflectionUtils.java:613)org.springframework.util.ReflectionUtils.doWithMethods(ReflectionUtils.java:524)org.springframework.util.ReflectionUtils.doWithMethods(ReflectionUtils.java:537)org.springframework.util.ReflectionUtils.doWithMethods(ReflectionUtils.java:510)org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.determineCandidateConstructors(AutowiredAnnotationBeanPostProcessor.java:247)org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.determineConstructorsFromBeanPostProcessors(AbstractAutowireCapableBeanFactory.java:1118)org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1091)org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:513)org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:483)org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:306)org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230)org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:302)org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:197)org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:761)org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:867)org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:543)org.springframework.web.servlet.FrameworkServlet.configureAndRefreshWebApplicationContext(FrameworkServlet.java:668)org.springframework.web.servlet.FrameworkServlet.createWebApplicationContext(FrameworkServlet.java:634)org.springframework.web.servlet.FrameworkServlet.createWebApplicationContext(FrameworkServlet.java:682)org.springframework.web.servlet.FrameworkServlet.initWebApplicationContext(FrameworkServlet.java:553)org.springframework.web.servlet.FrameworkServlet.initServletBean(FrameworkServlet.java:494)org.springframework.web.servlet.HttpServletBean.init(HttpServletBean.java:171)javax.servlet.GenericServlet.init(GenericServlet.java:158)sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)java.lang.reflect.Method.invoke(Unknown Source)org.apache.catalina.security.SecurityUtil$1.run(SecurityUtil.java:293)org.apache.catalina.security.SecurityUtil$1.run(SecurityUtil.java:290)java.security.AccessController.doPrivileged(Native Method)javax.security.auth.Subject.doAsPrivileged(Unknown Source)org.apache.catalina.security.SecurityUtil.execute(SecurityUtil.java:325)org.apache.catalina.security.SecurityUtil.doAsPrivilege(SecurityUtil.java:176)org.apache.catalina.security.SecurityUtil.doAsPrivilege(SecurityUtil.java:124)org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:504)org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79)org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:620)org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:502)org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1132)org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:684)org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1539)org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1495)java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)java.lang.Thread.run(Unknown Source)

note The full stack trace of the root cause is available in the Apache Tomcat/8.0.47 logs.

（2）分析：

      前端控制器（dispatcherServlet）Servlet初始化异常。

（3）原理：

     DispatcherServlet 是一个实实在在的 Servlet，所以 Spring MVC 引入后不会改变 Servlet 容器的行为，仍然是解析 web.xml 部署文件，只需要在里面配置这个 Servlet 即可。  

     DispatcherServlet 中具体实现请求的处理分发，先是把一些资源放到请求属性中，然后调用 doDispatch 实现请求分发到控制器的 handler