关于在使用spring出现类似java.sql.SQLException: Access denied for user 'XXX'@'localhost' (using password: YES)

如果你直接引用了官方文档的xml文件头（如下方）报错：

 xmlns="http://www.springframework.org/schema/beans"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xmlns:p="http://www.springframework.org/schema/p"
  xsi:schemaLocation="http://www.springframework.org/schema/beans
      http://www.springframework.org/schema/beans/spring-beans.xsd">

出现类似如下错误：com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask@4959d87f -- Acquisition Attempt Failed!!! Clearing pending acquires. While trying to acquire a needed new resource, we failed to succeed more than the maximum number of allowed acquisition attempts (30). Last acquisition attempt exception: 
java.sql.SQLException: Access denied for user 'XXX'@'localhost' (using password: YES)
	at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:1056)
	at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:957)
	at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3376)
	at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3308)
	at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:894)
	at com.mysql.jdbc.MysqlIO.secureAuth411(MysqlIO.java:3808)
	at com.mysql.jdbc.MysqlIO.doHandshake(MysqlIO.java:1256)
	at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2032)
	at com.mysql.jdbc.ConnectionImpl.(ConnectionImpl.java:729)
	at com.mysql.jdbc.JDBC4Connection.(JDBC4Connection.java:46)
	at sun.reflect.GeneratedConstructorAccessor7.newInstance(Unknown Source)
	at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27)
	at java.lang.reflect.Constructor.newInstance(Constructor.java:513)
	at com.mysql.jdbc.Util.handleNewInstance(Util.java:406)
	at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:302)
	at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:283)
	at com.mchange.v2.c3p0.DriverManagerDataSource.getConnection(DriverManagerDataSource.java:135)
	at com.mchange.v2.c3p0.WrapperConnectionPoolDataSource.getPooledConnection(WrapperConnectionPoolDataSource.java:182)
	at com.mchange.v2.c3p0.WrapperConnectionPoolDataSource.getPooledConnection(WrapperConnectionPoolDataSource.java:171)
	at com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool$1PooledConnectionResourcePoolManager.acquireResource(C3P0PooledConnectionPool.java:137)
	at com.mchange.v2.resourcepool.BasicResourcePool.doAcquire(BasicResourcePool.java:1014)
	at com.mchange.v2.resourcepool.BasicResourcePool.access$800(BasicResourcePool.java:32)
	at com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask.run(BasicResourcePool.java:1810)
	at com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread.run(ThreadPoolAsynchronousRunner.java:547)
2014-3-30 11:39:26 org.springframework.orm.hibernate4.HibernateTransactionManager afterPropertiesSet

那么请注意你的文件头少了一部分东西：应该配成如下方式：

 xmlns="http://www.springframework.org/schema/beans"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xmlns:p="http://www.springframework.org/schema/p"
  xsi:schemaLocation="http://www.springframework.org/schema/beans
      http://www.springframework.org/schema/beans/spring-beans-3.0.xsd">

请注意：红色部分是必须加上的，这是schema的版本号，必须得加，不加载的话不会正确的解析xml文件！

另外如果你不是因为这个原因导致的，那么在网上基本上都可以找到答案，例如数据库配置不正确等等之类的原因！