EJB3+JBOSS6+MySQL JBossResourceException: Could not create connection

开发EJB3是，JBoss连接MySQL数据库出现

09:40:30,890 WARN  [org.jboss.resource.connectionmanager.JBossManagedConnectionPool] Throwable while attempting to get a new connection: null: org.jboss.resource.JBossResourceException: Could not create connection; - nested throwable: (org.jboss.resource.JBossResourceException: Apparently wrong driver class specified for URL: class: com.mysql.jdbc.Driver, url: jdbc:mysql://localhost:3306/XXX)
	at org.jboss.resource.adapter.jdbc.local.LocalManagedConnectionFactory.getLocalManagedConnection(LocalManagedConnectionFactory.java:261) [:6.0.0.Final]
	at org.jboss.resource.adapter.jdbc.local.LocalManagedConnectionFactory.createManagedConnection(LocalManagedConnectionFactory.java:215) [:6.0.0.Final]
	at org.jboss.resource.connectionmanager.InternalManagedConnectionPool.createConnectionEventListener(InternalManagedConnectionPool.java:648) [:6.0.0.Final]

这是因为mysql-connector-java-bin.jar的位置不对，我将这个jar文件放在项目的/WEB-INFO/lib底下，正确的位置应该放在jboss_server_home/lib下，默认即 JBOSS安装目录/server/default/lib，这个异常就会消失，虽然我也不知道为什么。