Spring无法读取配置文件信息

做项目的时候，遇到一个这个错误，Spring配置文件无法读取 El 表达式所代表的信息

错误显示如下所示：

<span style="font-size:18px;">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 load JDBC driver class '${jdbc.driver}', cause: ${jdbc.driver}, cause: ${jdbc.driver}### The error may exist in mapper/UserMapper.xml### The error may involve ***.***.dao.UserMapper.select### The error occurred while executing a query### Cause: org.springframework.jdbc.CannotGetJdbcConnectionException: Could not get JDBC Connection; nested exception is org.apache.commons.dbcp.SQLNestedException: Cannot load JDBC driver class '${jdbc.driver}', cause: ${jdbc.driver}, cause: ${jdbc.driver}at org.mybatis.spring.MyBatisExceptionTranslator.translateExceptionIfPossible(MyBatisExceptionTranslator.java:75)at org.mybatis.spring.SqlSessionTemplate$SqlSessionInterceptor.invoke(SqlSessionTemplate.java:371)at com.sun.proxy.$Proxy13.selectOne(Unknown Source)at org.mybatis.spring.SqlSessionTemplate.selectOne(SqlSessionTemplate.java:163)at org.apache.ibatis.binding.MapperMethod.execute(MapperMethod.java:68)at org.apache.ibatis.binding.MapperProxy.invoke(MapperProxy.java:52)at com.sun.proxy.$Proxy14.select(Unknown Source)at ***.***.test.UserDaoTest.select(UserDaoTest.java:29)at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)at java.lang.reflect.Method.invoke(Method.java:606)at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:45)at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:15)at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:42)at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:20)at org.springframework.test.context.junit4.statements.RunBeforeTestMethodCallbacks.evaluate(RunBeforeTestMethodCallbacks.java:72)at org.springframework.test.context.junit4.statements.RunAfterTestMethodCallbacks.evaluate(RunAfterTestMethodCallbacks.java:81)at org.springframework.test.context.junit4.statements.SpringRepeat.evaluate(SpringRepeat.java:72)at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:263)at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:216)at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:82)at org.junit.runners.ParentRunner$3.run(ParentRunner.java:231)at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:60)at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:229)at org.junit.runners.ParentRunner.access$000(ParentRunner.java:50)at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:222)at org.springframework.test.context.junit4.statements.RunBeforeTestClassCallbacks.evaluate(RunBeforeTestClassCallbacks.java:60)at org.springframework.test.context.junit4.statements.RunAfterTestClassCallbacks.evaluate(RunAfterTestClassCallbacks.java:67)at org.junit.runners.ParentRunner.run(ParentRunner.java:300)at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.run(SpringJUnit4ClassRunner.java:162)at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:86)at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:459)at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:675)at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:382)at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:192)Caused by: org.apache.ibatis.exceptions.PersistenceException: ### Error querying database.  Cause: org.springframework.jdbc.CannotGetJdbcConnectionException: Could not get JDBC Connection; nested exception is org.apache.commons.dbcp.SQLNestedException: Cannot load JDBC driver class '${jdbc.driver}', cause: ${jdbc.driver}, cause: ${jdbc.driver}### The error may exist in mapper/UserMapper.xml### The error may involve ***.***.dao.UserMapper.select### The error occurred while executing a query### Cause: org.springframework.jdbc.CannotGetJdbcConnectionException: Could not get JDBC Connection; nested exception is org.apache.commons.dbcp.SQLNestedException: Cannot load JDBC driver class '${jdbc.driver}', cause: ${jdbc.driver}, cause: ${jdbc.driver}at org.apache.ibatis.exceptions.ExceptionFactory.wrapException(ExceptionFactory.java:26)at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:111)at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:102)at org.apache.ibatis.session.defaults.DefaultSqlSession.selectOne(DefaultSqlSession.java:66)at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)at java.lang.reflect.Method.invoke(Method.java:606)at org.mybatis.spring.SqlSessionTemplate$SqlSessionInterceptor.invoke(SqlSessionTemplate.java:358)... 35 moreCaused by: org.springframework.jdbc.CannotGetJdbcConnectionException: Could not get JDBC Connection; nested exception is org.apache.commons.dbcp.SQLNestedException: Cannot load JDBC driver class '${jdbc.driver}', cause: ${jdbc.driver}, cause: ${jdbc.driver}at org.springframework.jdbc.datasource.DataSourceUtils.getConnection(DataSourceUtils.java:80)at org.mybatis.spring.transaction.SpringManagedTransaction.openConnection(SpringManagedTransaction.java:81)at org.mybatis.spring.transaction.SpringManagedTransaction.getConnection(SpringManagedTransaction.java:67)at org.apache.ibatis.executor.BaseExecutor.getConnection(BaseExecutor.java:279)at org.apache.ibatis.executor.SimpleExecutor.prepareStatement(SimpleExecutor.java:72)at org.apache.ibatis.executor.SimpleExecutor.doQuery(SimpleExecutor.java:59)at org.apache.ibatis.executor.BaseExecutor.queryFromDatabase(BaseExecutor.java:267)at org.apache.ibatis.executor.BaseExecutor.query(BaseExecutor.java:137)at org.apache.ibatis.executor.CachingExecutor.query(CachingExecutor.java:96)at org.apache.ibatis.executor.CachingExecutor.query(CachingExecutor.java:77)at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:108)... 42 moreCaused by: org.apache.commons.dbcp.SQLNestedException: Cannot load JDBC driver class '${jdbc.driver}', cause: ${jdbc.driver}, cause: ${jdbc.driver}at org.apache.commons.dbcp.BasicDataSource.createDataSource(BasicDataSource.java:663)at org.apache.commons.dbcp.BasicDataSource.getConnection(BasicDataSource.java:430)at org.springframework.jdbc.datasource.DataSourceUtils.doGetConnection(DataSourceUtils.java:111)at org.springframework.jdbc.datasource.DataSourceUtils.getConnection(DataSourceUtils.java:77)... 52 moreCaused by: java.lang.ClassNotFoundException: ${jdbc.driver}at java.net.URLClassLoader$1.run(URLClassLoader.java:366)at java.net.URLClassLoader$1.run(URLClassLoader.java:355)at java.security.AccessController.doPrivileged(Native Method)at java.net.URLClassLoader.findClass(URLClassLoader.java:354)at java.lang.ClassLoader.loadClass(ClassLoader.java:425)at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:308)at java.lang.ClassLoader.loadClass(ClassLoader.java:358)at java.lang.Class.forName0(Native Method)at java.lang.Class.forName(Class.java:191)at org.apache.commons.dbcp.BasicDataSource.createDataSource(BasicDataSource.java:657)... 55 more</span>

通过测试发现是Spring配置文件中 <beans    ....... > 属性中的     default-autowire="byName"  属性配置问题

原因是Spring加载的先后顺序导致的。

有这句话时，当项目启动，Spring会将${jdbc.driver}等表达式当成字符串传过去，而不是将配置文件中所代表的值传过来。

解决方法：删除此属性即可。或者在程序中写个方法 重新加载配置文件中的内容。