Access denied for user 'xxx'@'localhost' 问题的解决方法

使用SpringMvc + Mybatis + Mysql搭建的架构，调试时出现了以下错误：

HTTP Status 500 - Request processing failed; nested exception is org.springframework.transaction.CannotCreateTransactionException: Could not open JDBC Connection for transaction; nested exception is java.sql.SQLException: Access denied for user 'Lzj'@'localhost' (using password: YES)

type Exception report

message Request processing failed; nested exception is org.springframework.transaction.CannotCreateTransactionException: Could not open JDBC Connection for transaction; nested exception is java.sql.SQLException: Access denied for user 'Lzj'@'localhost' (using password: YES)

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

exception

org.springframework.web.util.NestedServletException: Request processing failed; nested exception is org.springframework.transaction.CannotCreateTransactionException: Could not open JDBC Connection for transaction; nested exception is java.sql.SQLException: Access denied for user 'Lzj'@'localhost' (using password: YES)
    org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:982)
    org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:861)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:622)
    org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:846)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
    org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
    org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:197)
    org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
root cause

org.springframework.transaction.CannotCreateTransactionException: Could not open JDBC Connection for transaction; nested exception is java.sql.SQLException: Access denied for user 'Lzj'@'localhost' (using password: YES)
    org.springframework.jdbc.datasource.DataSourceTransactionManager.doBegin(DataSourceTransactionManager.java:289)
    org.springframework.transaction.support.AbstractPlatformTransactionManager.getTransaction(AbstractPlatformTransactionManager.java:373)
    org.springframework.transaction.interceptor.TransactionAspectSupport.createTransactionIfNecessary(TransactionAspectSupport.java:447)
    org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:277)
    org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:96)
    org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
    org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:92)
    org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
    org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:213)
    com.sun.proxy.$Proxy15.list(Unknown Source)
    com.lzj.controller.HelloController.hello(HelloController.java:25)
    sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    java.lang.reflect.Method.invoke(Method.java:498)
    org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:205)
    org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:133)
    org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:116)
    org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:827)
    org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:738)
    org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:85)
    org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:963)
    org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:897)
    org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:970)
    org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:861)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:622)
    org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:846)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
    org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
    org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:197)
    org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
root cause

java.sql.SQLException: Access denied for user 'Lzj'@'localhost' (using password: YES)
    com.mysql.jdbc.SQLError.createSQLException(SQLError.java:964)
    com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3973)
    com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3909)
    com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:873)
    com.mysql.jdbc.MysqlIO.proceedHandshakeWithPluggableAuthentication(MysqlIO.java:1710)
    com.mysql.jdbc.MysqlIO.doHandshake(MysqlIO.java:1226)
    com.mysql.jdbc.ConnectionImpl.coreConnect(ConnectionImpl.java:2205)
    com.mysql.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:2236)
    com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2035)
    com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:790)
    com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:47)
    sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
    sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
    sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
    java.lang.reflect.Constructor.newInstance(Constructor.java:423)
    com.mysql.jdbc.Util.handleNewInstance(Util.java:425)
    com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:400)
    com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:330)
    java.sql.DriverManager.getConnection(DriverManager.java:664)
    java.sql.DriverManager.getConnection(DriverManager.java:208)
    org.springframework.jdbc.datasource.DriverManagerDataSource.getConnectionFromDriverManager(DriverManagerDataSource.java:153)
    org.springframework.jdbc.datasource.DriverManagerDataSource.getConnectionFromDriver(DriverManagerDataSource.java:144)
    org.springframework.jdbc.datasource.AbstractDriverBasedDataSource.getConnectionFromDriver(AbstractDriverBasedDataSource.java:196)
    org.springframework.jdbc.datasource.AbstractDriverBasedDataSource.getConnection(AbstractDriverBasedDataSource.java:159)
    org.springframework.jdbc.datasource.DataSourceTransactionManager.doBegin(DataSourceTransactionManager.java:246)
    org.springframework.transaction.support.AbstractPlatformTransactionManager.getTransaction(AbstractPlatformTransactionManager.java:373)
    org.springframework.transaction.interceptor.TransactionAspectSupport.createTransactionIfNecessary(TransactionAspectSupport.java:447)
    org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:277)
    org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:96)
    org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
    org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:92)
    org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
    org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:213)
    com.sun.proxy.$Proxy15.list(Unknown Source)
    com.lzj.controller.HelloController.hello(HelloController.java:25)
    sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    java.lang.reflect.Method.invoke(Method.java:498)
    org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:205)
    org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:133)
    org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:116)
    org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:827)
    org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:738)
    org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:85)
    org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:963)
    org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:897)
    org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:970)
    org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:861)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:622)
    org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:846)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
    org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
    org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:197)
    org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)

网上的一些说法是数据库没有访问权限，当然这是一种情况。

起始还有另一种可能，就是框架没有拿到datasource正确的username，这个和配置有关：

我原先的applicationContext.xml文件配置是这样的：

    <!-- 加载properties -->
    <context:property-placeholder location="classpath:datasource.properties" />

    <!--  配置datasource  -->
    <bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource" >
        <property name="driverClassName" value="${driverClassName}"/>
        <property name="url" value="${url}"/>
        <property name="username" value="${username}"/>
        <property name="password" value="${password}"/>
    </bean>

datasource.properties文件代码如下：

driverClassName=com.mysql.jdbc.Driver
url=jdbc:mysql://127.0.0.1:3306/test
username=root
password=test

这样框架在构造AbstractDriverBasedDataSource实例时，拿到的username始终是当前机器名。

我也没有找到构造username的代码！

最后将datasource.properties文件的username改为jdbc.username,即：

driverClassName=com.mysql.jdbc.Driver
url=jdbc:mysql://127.0.0.1:3306/test
jdbc.username=root
password=test

applicationContext.xml文件的dataSource的bean配置如下：

    <!--  配置datasource  -->
    <bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource" >
        <property name="driverClassName" value="${driverClassName}"/>
        <property name="url" value="${url}"/>
        <property name="username" value="${jdbc.username}"/>
        <property name="password" value="${password}"/>
    </bean>

这样就解决了，每次都拿错username的问题。具体是什么原因，我也不知道。还需要在研读源码。

各位如有知道原因的，请留言。

后续如有答案，我会补上。