with open('2.txt','r',encoding='utf-8') as f:
    Str=f.readline()
    Str=[aa.rstrip()+'#'+str(a) for a,aa in enumerate(Str)]
with open('2.txt','w',encoding='utf-8') as f:
    f.writelines(Str)

txt文件内容：

wonishibaba



运行后：w#0o#1是#2n#3i#4爸#5爸#6#7

问题：为什么会这样的 跟视频不同

这个页面出现报错。麻烦看一下。老师，我这个报错，看了看不太明白

[WARNING] No mapping for GET /

7月 10, 2021 6:22:51 下午 org.apache.catalina.core.StandardWrapperValve invoke

严重: Servlet.service() for servlet [springmvc] in context with path [] threw exception [Request processing failed; nested exception is org.springframework.transaction.CannotCreateTransactionException: Could not open JDBC Connection for transaction; nested exception is com.mysql.jdbc.exceptions.jdbc4.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.] with root cause

java.net.ConnectException: Connection refused: 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.jdbc.StandardSocketFactory.connect(StandardSocketFactory.java:211)

at com.mysql.jdbc.MysqlIO.<init>(MysqlIO.java:298)

at com.mysql.jdbc.ConnectionImpl.coreConnect(ConnectionImpl.java:2253)

at com.mysql.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:2286)

at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2085)

at com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:795)

at com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:44)

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.newInstance(Constructor.java:490)

at com.mysql.jdbc.Util.handleNewInstance(Util.java:404)

at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:400)

at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:327)

at java.sql/java.sql.DriverManager.getConnection(DriverManager.java:677)

at java.sql/java.sql.DriverManager.getConnection(DriverManager.java:189)

at org.springframework.jdbc.datasource.DriverManagerDataSource.getConnectionFromDriverManager(DriverManagerDataSource.java:155)

at org.springframework.jdbc.datasource.DriverManagerDataSource.getConnectionFromDriver(DriverManagerDataSource.java:146)

at org.springframework.jdbc.datasource.AbstractDriverBasedDataSource.getConnectionFromDriver(AbstractDriverBasedDataSource.java:205)

at org.springframework.jdbc.datasource.AbstractDriverBasedDataSource.getConnection(AbstractDriverBasedDataSource.java:169)

at org.springframework.jdbc.datasource.DataSourceTransactionManager.doBegin(DataSourceTransactionManager.java:263)

at org.springframework.transaction.support.AbstractPlatformTransactionManager.startTransaction(AbstractPlatformTransactionManager.java:400)

at org.springframework.transaction.support.AbstractPlatformTransactionManager.getTransaction(AbstractPlatformTransactionManager.java:373)

at org.springframework.transaction.interceptor.TransactionAspectSupport.createTransactionIfNecessary(TransactionAspectSupport.java:572)

at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:360)

at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:99)

at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186)

at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:95)

at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186)

at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:212)

at com.sun.proxy.$Proxy40.addUsers(Unknown Source)

at com.bjsxt.web.controller.UsersController.addUsers(UsersController.java:22)

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:566)

at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:190)

at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:138)

at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:106)

at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:879)

at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:793)

at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87)

at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1040)

at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:943)

at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1006)

at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:909)

at javax.servlet.http.HttpServlet.service(HttpServlet.java:647)

at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:883)

at javax.servlet.http.HttpServlet.service(HttpServlet.java:728)

at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)

at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)

at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:51)

at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)

at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)

at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201)

at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)

at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)

at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)

at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:222)

at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:123)

at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502)

at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:171)

at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:100)

at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:953)

at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)

at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:408)

at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1041)

at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:603)

at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:312)

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)

[WARNING] No mapping for GET /users/findUsers

7月 10, 2021 6:24:37 下午 org.apache.catalina.core.StandardWrapperValve invoke

严重: Servlet.service() for servlet [springmvc] in context with path [] threw exception [Request processing failed; nested exception is org.springframework.transaction.CannotCreateTransactionException: Could not open JDBC Connection for transaction; nested exception is com.mysql.jdbc.exceptions.jdbc4.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.] with root cause

java.net.ConnectException: Connection refused: 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.jdbc.StandardSocketFactory.connect(StandardSocketFactory.java:211)

at com.mysql.jdbc.MysqlIO.<init>(MysqlIO.java:298)

at com.mysql.jdbc.ConnectionImpl.coreConnect(ConnectionImpl.java:2253)

at com.mysql.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:2286)

at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2085)

at com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:795)

at com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:44)

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.newInstance(Constructor.java:490)

at com.mysql.jdbc.Util.handleNewInstance(Util.java:404)

at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:400)

at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:327)

at java.sql/java.sql.DriverManager.getConnection(DriverManager.java:677)

at java.sql/java.sql.DriverManager.getConnection(DriverManager.java:189)

at org.springframework.jdbc.datasource.DriverManagerDataSource.getConnectionFromDriverManager(DriverManagerDataSource.java:155)

at org.springframework.jdbc.datasource.DriverManagerDataSource.getConnectionFromDriver(DriverManagerDataSource.java:146)

at org.springframework.jdbc.datasource.AbstractDriverBasedDataSource.getConnectionFromDriver(AbstractDriverBasedDataSource.java:205)

at org.springframework.jdbc.datasource.AbstractDriverBasedDataSource.getConnection(AbstractDriverBasedDataSource.java:169)

at org.springframework.jdbc.datasource.DataSourceTransactionManager.doBegin(DataSourceTransactionManager.java:263)

at org.springframework.transaction.support.AbstractPlatformTransactionManager.startTransaction(AbstractPlatformTransactionManager.java:400)

at org.springframework.transaction.support.AbstractPlatformTransactionManager.getTransaction(AbstractPlatformTransactionManager.java:373)

at org.springframework.transaction.interceptor.TransactionAspectSupport.createTransactionIfNecessary(TransactionAspectSupport.java:572)

at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:360)

at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:99)

at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186)

at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:95)

at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186)

at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:212)

at com.sun.proxy.$Proxy40.addUsers(Unknown Source)

at com.bjsxt.web.controller.UsersController.addUsers(UsersController.java:22)

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:566)

at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:190)

at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:138)

at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:106)

at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:879)

at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:793)

at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87)

at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1040)

at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:943)

at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1006)

at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:909)

at javax.servlet.http.HttpServlet.service(HttpServlet.java:647)

at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:883)

at javax.servlet.http.HttpServlet.service(HttpServlet.java:728)

at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)

at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)

at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:51)

at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)

at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)

at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201)

at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)

at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)

at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)

at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:222)

at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:123)

at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502)

at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:171)

at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:100)

at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:953)

at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)

at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:408)

at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1041)

at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:603)

at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:312)

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)

7月 10, 2021 6:24:41 下午 org.apache.catalina.core.StandardWrapperValve invoke

严重: Servlet.service() for servlet [springmvc] in context with path [] threw exception [Request processing failed; nested exception is org.springframework.transaction.CannotCreateTransactionException: Could not open JDBC Connection for transaction; nested exception is com.mysql.jdbc.exceptions.jdbc4.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.] with root cause

java.net.ConnectException: Connection refused: 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.jdbc.StandardSocketFactory.connect(StandardSocketFactory.java:211)

at com.mysql.jdbc.MysqlIO.<init>(MysqlIO.java:298)

at com.mysql.jdbc.ConnectionImpl.coreConnect(ConnectionImpl.java:2253)

at com.mysql.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:2286)

at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2085)

at com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:795)

at com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:44)

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.newInstance(Constructor.java:490)

at com.mysql.jdbc.Util.handleNewInstance(Util.java:404)

at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:400)

at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:327)

at java.sql/java.sql.DriverManager.getConnection(DriverManager.java:677)

at java.sql/java.sql.DriverManager.getConnection(DriverManager.java:189)

at org.springframework.jdbc.datasource.DriverManagerDataSource.getConnectionFromDriverManager(DriverManagerDataSource.java:155)

at org.springframework.jdbc.datasource.DriverManagerDataSource.getConnectionFromDriver(DriverManagerDataSource.java:146)

at org.springframework.jdbc.datasource.AbstractDriverBasedDataSource.getConnectionFromDriver(AbstractDriverBasedDataSource.java:205)

at org.springframework.jdbc.datasource.AbstractDriverBasedDataSource.getConnection(AbstractDriverBasedDataSource.java:169)

at org.springframework.jdbc.datasource.DataSourceTransactionManager.doBegin(DataSourceTransactionManager.java:263)

at org.springframework.transaction.support.AbstractPlatformTransactionManager.startTransaction(AbstractPlatformTransactionManager.java:400)

at org.springframework.transaction.support.AbstractPlatformTransactionManager.getTransaction(AbstractPlatformTransactionManager.java:373)

at org.springframework.transaction.interceptor.TransactionAspectSupport.createTransactionIfNecessary(TransactionAspectSupport.java:572)

at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:360)

at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:99)

at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186)

at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:95)

at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186)

at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:212)

at com.sun.proxy.$Proxy40.addUsers(Unknown Source)

at com.bjsxt.web.controller.UsersController.addUsers(UsersController.java:22)

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:566)

at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:190)

at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:138)

at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:106)

at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:879)

at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:793)

at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87)

at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1040)

at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:943)

at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1006)

at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:909)

at javax.servlet.http.HttpServlet.service(HttpServlet.java:647)

at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:883)

at javax.servlet.http.HttpServlet.service(HttpServlet.java:728)

at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)

at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)

at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:51)

at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)

at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)

at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201)

at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)

at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)

at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)

at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:222)

at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:123)

at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502)

at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:171)

at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:100)

at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:953)

at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)

at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:408)

at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1041)

at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:603)

at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:310)

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)

老师，这个报错了，麻烦看一下？

老师，我不明白什么程序为什么知道此时执行的是updateUsers方法

那我此时要是有多个方法，程序不就报错了吗，就没办法实现需求了吗

老师，不知为何，按照老师讲的，老师那里可以运行tomcat，我这里就不行。

from music_project.dbutil import dbutil

class Myservice:

    def myuser(self):
        self.user = None

    def login(self,uname,password):
        sql = "select * from t_user where uname=%s and password=%s"
        user = dbutil().query_one(sql,uname,password)
        if user:
            self.user = user
            return True
        else:
            return False
    # 添加音乐的方法，有可能是一首，有可能是多首，所以可以进行遍历
    def add_music(self,files):
        for f in files:
            start = f.rfind(r"/")+1
            end = f.rfind(".mp3")
            music_name = f[start:end]
            print(music_name)
            # # 查询歌曲是否已经存在进行判断
            sql = 'select * from t_music where music_name = %s'
            music = dbutil.query_one(sql,music_name)
            if music:
                # 查询关联表t_list是否已经存在歌曲
                sql = "select * from t_list where uid = %s and mid = %s"
                t_list = dbutil().query_one(sql,self.user[0],music[0])
                if not t_list:
                    sql = 'insert into t_list(mid,uid) values(%s,%s)'
                    dbutil.DMLsql(sql,music[0],self.user[0])
            else:
                # 将音乐保存到t_musict表中
                sql = 'insert into t_music(music_name,path) values(%s,%s)'
                mid = dbutil().DMLsql(sql, music_name, f)
                # 用户选择的音乐保存到t_list
                sql = 'insert into t_list(mid,uid) values(%s,%s)'
                dbutil().DMLsql(sql, mid, self.user[0])

老师，请问下，我在执行到进行判断添加的歌曲是否已经存在数据库中的这一步，出现这个错误代码，是怎么回事

老师，我能不能理解成，这案例中，自动cgib生成的代理，就不用像上节课那样子去动态代理或者静态代理。

from urllib.request import urlopen
from urllib.request import Request
from random import choice

url = "https://www.baidu.com/"
user_agents=[
    "ua1","ua2","ua3"
]
# print(choice(user_agents))
#定义user_Agent变量
headers = {
   "User-Agent": choice(user_agents)

}
#封装request对象
req = Request(url,headers=headers)
print(req.get_header("User-agent"))
#发送请求
# resp = urlopen(req)
# print(resp.read().decode())

print(req.get_header("User-agent"))

这句中，User-agent和User-Agent大写与小写有什么区别吗？而且这块不是应该与headers语句的中User-Agent一致吗？

为什么没有venv文件

创建了新的虚拟环境(baizhan111) E:\PycharmProjects\baizhan111>也没有venv文件

老师，为什么在python中单字符既可以使用单引号，也可以使用双引号。

老师 我用的是MySQL 用连接|| 的时候数据库中的数据都正确，但是输出的也全是1或者全是0

老师，我在做使用 while 循环：计算 1-100 之间所有数字的和，所有偶数的和，所有奇数的和时，为什么运行完是这样？

老师你好，这些课堂上ppt后面的作业答案在哪里找？

老师问一下input == null!这个怎么解决

老师，是不是每次在dao层创建一个方法也都应该在service层创建一个方法？