Spring配置c3p0无法连接数据库(用户名问题)

我的spring中的数据源：

	<bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource">
	   <property name="driverClass" value="${driver}"/>
	   <property name="jdbcUrl" value="${url}"/>
	   <property name="user" value="${username}"/>
	   <property name="password" value="${password}"/>
	</bean>

我的db.properties:

driver=com.mysql.cj.jdbc.Driver
url=jdbc:mysql://localhost:3306/login?&characterEncoding=utf-8&useUnicode=true
username=root
password=123456

看起来没啥毛病吧？
它报错了：

java.sql.SQLException: Access denied for user 'qin'@'localhost' (using password: YES)
	at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:129)
	at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:97)
	at com.mysql.cj.jdbc.exceptions.SQLExceptionsMapping.translateException(SQLExceptionsMapping.java:122)
	at com.mysql.cj.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:836)
	at com.mysql.cj.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:456)
	at com.mysql.cj.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:246)
	at com.mysql.cj.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:197)
	at com.mchange.v2.c3p0.DriverManagerDataSource.getConnection(DriverManagerDataSource.java:175)
	at com.mchange.v2.c3p0.WrapperConnectionPoolDataSource.getPooledConnection(WrapperConnectionPoolDataSource.java:220)
	at com.mchange.v2.c3p0.WrapperConnectionPoolDataSource.getPooledConnection(WrapperConnectionPoolDataSource.java:206)
	at com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool$1PooledConnectionResourcePoolManager.acquireResource(C3P0PooledConnectionPool.java:203)
	at com.mchange.v2.resourcepool.BasicResourcePool.doAcquire(BasicResourcePool.java:1176)
	at com.mchange.v2.resourcepool.BasicResourcePool.doAcquireAndDecrementPendingAcquiresWithinLockOnSuccess(BasicResourcePool.java:1163)
	at com.mchange.v2.resourcepool.BasicResourcePool.access$700(BasicResourcePool.java:44)
	at com.mchange.v2.resourcepool.BasicResourcePool$ScatteredAcquireTask.run(BasicResourcePool.java:1908)
	at com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread.run(ThreadPoolAsynchronousRunner.java:696)

What ?
为啥我在db.properties里配置的是root，它给我报错，报的java.sql.SQLException: Access denied for user 'qin'@'localhost' (using password: YES) ，用户名变成了qin，这不是我电脑的用户名吗？所以我推测username, password可能是系统的关键字，于是我改掉db.properties中：

jdbc.driver=com.mysql.cj.jdbc.Driver
jdbc.url=jdbc:mysql://localhost:3306/login?&characterEncoding=utf-8&useUnicode=true
jdbc.username=root
jdbc.password=123456

在前面加上了jdbc. ，并修改xml文件:

    <!--    数据源-->
    <bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource">
        <property name="driverClass" value="${jdbc.driver}"/>
        <property name="jdbcUrl" value="${jdbc.url}"/>
        <property name="user" value="${jdbc.username}"/>
        <property name="password" value="${jdbc.password}"/>
    </bean>

就好了。。。