老师这个是哪里错了

错误显示

java.lang.reflect.InvocationTargetException
	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:567)
	at com.imooc.icake.global.GlobalController.service(GlobalController.java:57)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
	at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
	at com.imooc.icake.global.EncodingFilter.doFilter(EncodingFilter.java:21)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
	at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:202)
	at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96)
	at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:490)
	at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:139)
	at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92)
	at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:678)
	at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:74)
	at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343)
	at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:408)
	at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66)
	at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:853)
	at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1587)
	at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
	at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
	at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
	at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
	at java.base/java.lang.Thread.run(Thread.java:835)
Caused by: org.apache.ibatis.exceptions.PersistenceException: 
### Error querying database.  Cause: com.mysql.cj.jdbc.exceptions.CommunicationsException: Communications link failure

The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.
### The error may exist in com/imooc/icake/dao/CatalogDao.java (best guess)
### The error may involve com.imooc.icake.dao.CatalogDao.select
### The error occurred while executing a query
### Cause: com.mysql.cj.jdbc.exceptions.CommunicationsException: Communications link failure

The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.
	at org.apache.ibatis.exceptions.ExceptionFactory.wrapException(ExceptionFactory.java:30)
	at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:149)
	at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:140)
	at org.apache.ibatis.session.defaults.DefaultSqlSession.selectOne(DefaultSqlSession.java:76)
	at org.apache.ibatis.binding.MapperMethod.execute(MapperMethod.java:87)
	at org.apache.ibatis.binding.MapperProxy.invoke(MapperProxy.java:57)
	at com.sun.proxy.$Proxy14.select(Unknown Source)
	at com.imooc.icake.biz.impl.CatalogBizImpl.getRoot(CatalogBizImpl.java:39)
	at com.imooc.icake.controller.CatalogController.list(CatalogController.java:23)
	... 30 more
Caused by: com.mysql.cj.jdbc.exceptions.CommunicationsException: Communications link failure

The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.
	at com.mysql.cj.jdbc.exceptions.SQLError.createCommunicationsException(SQLError.java:174)
	at com.mysql.cj.jdbc.exceptions.SQLExceptionsMapping.translateException(SQLExceptionsMapping.java:64)
	at com.mysql.cj.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:827)
	at com.mysql.cj.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:447)
	at com.mysql.cj.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:237)
	at com.mysql.cj.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:199)
	at java.sql/java.sql.DriverManager.getConnection(DriverManager.java:677)
	at java.sql/java.sql.DriverManager.getConnection(DriverManager.java:189)
	at org.apache.ibatis.datasource.unpooled.UnpooledDataSource.doGetConnection(UnpooledDataSource.java:221)
	at org.apache.ibatis.datasource.unpooled.UnpooledDataSource.doGetConnection(UnpooledDataSource.java:216)
	at org.apache.ibatis.datasource.unpooled.UnpooledDataSource.getConnection(UnpooledDataSource.java:95)
	at org.apache.ibatis.datasource.pooled.PooledDataSource.popConnection(PooledDataSource.java:422)
	at org.apache.ibatis.datasource.pooled.PooledDataSource.getConnection(PooledDataSource.java:89)
	at org.apache.ibatis.transaction.jdbc.JdbcTransaction.openConnection(JdbcTransaction.java:138)
	at org.apache.ibatis.transaction.jdbc.JdbcTransaction.getConnection(JdbcTransaction.java:60)
	at org.apache.ibatis.executor.BaseExecutor.getConnection(BaseExecutor.java:336)
	at org.apache.ibatis.executor.SimpleExecutor.prepareStatement(SimpleExecutor.java:85)
	at org.apache.ibatis.executor.SimpleExecutor.doQuery(SimpleExecutor.java:62)
	at org.apache.ibatis.executor.BaseExecutor.queryFromDatabase(BaseExecutor.java:324)
	at org.apache.ibatis.executor.BaseExecutor.query(BaseExecutor.java:156)
	at org.apache.ibatis.executor.CachingExecutor.query(CachingExecutor.java:109)
	at org.apache.ibatis.executor.CachingExecutor.query(CachingExecutor.java:83)
	at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:147)
	... 37 more
Caused by: com.mysql.cj.exceptions.CJCommunicationsException: Communications link failure

The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.
	at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
	at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
	at java.base/jdk.internal.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
	at java.base/java.lang.reflect.Constructor.newInstanceWithCaller(Constructor.java:500)
	at java.base/java.lang.reflect.Constructor.newInstance(Constructor.java:481)
	at com.mysql.cj.exceptions.ExceptionFactory.createException(ExceptionFactory.java:61)
	at com.mysql.cj.exceptions.ExceptionFactory.createException(ExceptionFactory.java:105)
	at com.mysql.cj.exceptions.ExceptionFactory.createException(ExceptionFactory.java:151)
	at com.mysql.cj.exceptions.ExceptionFactory.createCommunicationsException(ExceptionFactory.java:167)
	at com.mysql.cj.protocol.a.NativeSocketConnection.connect(NativeSocketConnection.java:91)
	at com.mysql.cj.NativeSession.connect(NativeSession.java:150)
	at com.mysql.cj.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:947)
	at com.mysql.cj.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:817)
	... 57 more
Caused by: java.net.ConnectException: Connection timed out: connect
	at java.base/java.net.PlainSocketImpl.connect0(Native Method)
	at java.base/java.net.PlainSocketImpl.socketConnect(PlainSocketImpl.java:101)
	at java.base/java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:399)
	at java.base/java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:242)
	at java.base/java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:224)
	at java.base/java.net.SocksSocketImpl.connect(SocksSocketImpl.java:403)
	at java.base/java.net.Socket.connect(Socket.java:591)
	at com.mysql.cj.protocol.StandardSocketFactory.connect(StandardSocketFactory.java:155)
	at com.mysql.cj.protocol.a.NativeSocketConnection.connect(NativeSocketConnection.java:65)
	... 60 more

GlobalController 代码

package com.imooc.icake.global;

import javax.servlet.GenericServlet;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;

public class GlobalController extends GenericServlet {

    /**
     * 根据用户的url 分辨出有哪个类的那个方法
     */
    @Override
    public void service(ServletRequest req, ServletResponse resp) throws ServletException, IOException {
        /*
         .do 后缀的请求交给这个servlet
         /login.do              DefaultController login
         /Cake/detail.do        CakeController    detail
         /admin/Cake/add.do     CakeController    add
         */
        //强制类型转换
        HttpServletRequest request=(HttpServletRequest)req;
        HttpServletResponse response=(HttpServletResponse)resp;
        String path=request.getServletPath();//获得请求路径
        //判断前台还是后台的
        if(path.indexOf("/admin")!=-1){
            path=path.substring(7);
        }else {
            path=path.substring(1);
        }
        //去掉后path的格式
        /*
         login.do              DefaultController login
         Cake/detail.do        CakeController    detail
         Cake/add.do     CakeController    add
         */
        int index=path.indexOf("/");
        String className=null;
        String methodName=null;
        if(index!=-1){
            className="com.imooc.icake.controller."+path.substring(0,index)+"Controller";
            methodName=path.substring(index+1,path.indexOf(".do"));
        }else {
            className="com.imooc.icake.controller.DefaultController";
            methodName=path.substring(0,path.indexOf(".do"));
        }

        try {
            Class cla=Class.forName(className);
            Object object=cla.newInstance();
            Method method=cla.getMethod(methodName,HttpServletRequest.class,HttpServletResponse.class);
            method.invoke(object,request,response);
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } catch (IllegalAccessException e) {
            e.printStackTrace();
        } catch (InstantiationException | NoSuchMethodException e) {
            e.printStackTrace();
        } catch (InvocationTargetException e) {
            e.printStackTrace();
        }
    }
}