刚启动没有这个异常，运行一段时间后就会出现，什么原因导致的
严重: Servlet.service() for servlet springMVC threw exception
java.io.EOFException: Can not read response from server. Expected to read 4 bytes, read 0 bytes before connection was unexpectedly lost.
at com.mysql.jdbc.MysqlIO.readFully(MysqlIO.java:2926)
at com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:3344)
at com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:3334)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3774)
at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:2447)
at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2594)
at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2541)
at com.mysql.jdbc.ConnectionImpl.setAutoCommit(ConnectionImpl.java:4882)
at sun.reflect.GeneratedMethodAccessor46.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:497)
at org.apache.ibatis.datasource.pooled.PooledConnection.invoke(PooledConnection.java:245)
at com.sun.proxy.$Proxy10.setAutoCommit(Unknown Source)
at org.apache.ibatis.transaction.jdbc.JdbcTransaction.setDesiredAutoCommit(JdbcTransaction.java:104)
at org.apache.ibatis.transaction.jdbc.JdbcTransaction.openConnection(JdbcTransaction.java:144)
at org.apache.ibatis.transaction.jdbc.JdbcTransaction.getConnection(JdbcTransaction.java:62)
at org.apache.ibatis.executor.BaseExecutor.getConnection(BaseExecutor.java:315)
at org.apache.ibatis.executor.SimpleExecutor.prepareStatement(SimpleExecutor.java:75)
at org.apache.ibatis.executor.SimpleExecutor.doQuery(SimpleExecutor.java:61)
at org.apache.ibatis.executor.BaseExecutor.queryFromDatabase(BaseExecutor.java:303)
at org.apache.ibatis.executor.BaseExecutor.query(BaseExecutor.java:154)
at org.apache.ibatis.executor.CachingExecutor.query(CachingExecutor.java:102)
at org.apache.ibatis.executor.CachingExecutor.query(CachingExecutor.java:82)
at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:120)
at com.mybatis.MybatisUtils.selectPagingList(MybatisUtils.java:125)
at com.dao.TxtDao.selectTxtByCond(TxtDao.java:24)
at com.controller.TxtController.viewLesson(TxtController.java:136)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:497)
at org.springframework.web.bind.annotation.support.HandlerMethodInvoker.invokeHandlerMethod(HandlerMethodInvoker.java:176)
at org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter.invokeHandlerMethod(AnnotationMethodHandlerAdapter.java:426)
at org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter.handle(AnnotationMethodHandlerAdapter.java:414)
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:790)
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:719)
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:644)
at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:549)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:617)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:723)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at com.filter.CharsetFilter.doFilter(CharsetFilter.java:45)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:103)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:293)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:861)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:620)
at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489)
at java.lang.Thread.run(Thread.java:745)
