错误信息展示：

org.mybatis.spring.MyBatisSystemException: nested exception is org.apache.ibatis.exceptions.PersistenceException: 
### Error querying database.  Cause: org.springframework.jdbc.CannotGetJdbcConnectionException: Could not get JDBC Connection; nested exception is org.apache.commons.dbcp.SQLNestedException: Cannot create PoolableConnectionFactory (Access denied for user ''@'localhost' to database 'stu')
### The error may exist in file [E:\IDEAspace\Spring\SpringMybaties\target\classes\com\baizhi\mapper\StudentDaoMapper.xml]
### The error may involve com.baizhi.dao.StudentDao.query
### The error occurred while executing a query
### Cause: org.springframework.jdbc.CannotGetJdbcConnectionException: Could not get JDBC Connection; nested exception is org.apache.commons.dbcp.SQLNestedException: Cannot create PoolableConnectionFactory (Access denied for user ''@'localhost' to database 'stu')

	at org.mybatis.spring.MyBatisExceptionTranslator.translateExceptionIfPossible(MyBatisExceptionTranslator.java:77)
	at org.mybatis.spring.SqlSessionTemplate$SqlSessionInterceptor.invoke(SqlSessionTemplate.java:446)
	at com.sun.proxy.$Proxy9.selectList(Unknown Source)
	at org.mybatis.spring.SqlSessionTemplate.selectList(SqlSessionTemplate.java:230)
	at org.apache.ibatis.binding.MapperMethod.executeForMany(MapperMethod.java:119)
	at org.apache.ibatis.binding.MapperMethod.execute(MapperMethod.java:63)
	at org.apache.ibatis.binding.MapperProxy.invoke(MapperProxy.java:52)
	at com.sun.proxy.$Proxy10.query(Unknown Source)
	at com.baizhi.test.TestDAO.testSelectAll(TestDAO.java:16)
	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:498)
	at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)
	at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
	at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
	at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
	at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)
	at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:78)
	at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:57)
	at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
	at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
	at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
	at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
	at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
	at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
	at org.junit.runner.JUnitCore.run(JUnitCore.java:137)
	at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:68)
	at com.intellij.rt.execution.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:47)
	at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:242)
	at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:70)

解决办法一（详）：

错误的小配置文件：

driver:com.mysql.jdbc.Driver
url:jdbc:mysql://localhost:3306/stu?characterEncoding=UTF-8
username:root
password:

注：配置信息根据自己的配置

错误的spring配置：

 <!--读取小配置文件  获取连接数据库的参数-->
   <context:property-placeholder location="jdbc.properties"></context:property-placeholder>

    <!--配置数据源   使用DBCP连接池-->
    <bean id="basicDataSource" class="org.apache.commons.dbcp.BasicDataSource">
        <!--连接数据库的相关参数-->
        <property name="driverClassName" value="${driver}"></property>
        <property name="url" value="${url}"></property>
        <property name="username" value="${username}"></property>
        <property name="password" value="${password}"></property>

    </bean>

正确的小配置文件：

jdbc.driver:com.mysql.jdbc.Driver
jdbc.url:jdbc:mysql://localhost:3306/stu?characterEncoding=UTF-8
jdbc.username:root
jdbc.password:

正确的spring配置：

 <!--读取小配置文件  获取连接数据库的参数-->
   <context:property-placeholder location="jdbc.properties"></context:property-placeholder>

    <!--配置数据源   使用DBCP连接池-->
    <bean id="basicDataSource" class="org.apache.commons.dbcp.BasicDataSource">
        <!--连接数据库的相关参数-->
        <property name="driverClassName" value="${jdbc.driver}"></property>
        <property name="url" value="${jdbc.url}"></property>
        <property name="username" value="${jdbc.username}"></property>
        <property name="password" value="${jdbc.password}"></property>

    </bean>

解决办法二（略）：

如果上述方法未能解决你的异常，你可以尝试着用IDEA或者MyEclipse集成工具连接一下数据库，具体方法可以搜索比如IDEA集成mysql数据库等，这样做的目的是先排除一下你书写的配置信息是否有误。

解决办法三（略）：

检查数据库的服务是否已经打开，具体方法百度。

解决办法四（略）：

更换相关jar包，可能是版本不兼容所导致的。

笔者今天遇到这个问题，主要想到的解决办法就是后三种，对第一种解决办法不是很了解，最终查阅了相关API后问题才得到解决，记录一下。