BAE3.0中mysql连接超时问题?报错

日志报错如下：

Caused by: com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure
at java.lang.Thread.run(Thread.java:724)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:310)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:603)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1041)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:408)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:100)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:171)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:123)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:222)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)
at com.core.web.filter.GateFilter.doFilter(GateFilter.java:52)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)
at com.core.web.filter.LoginFilter.doFilter(LoginFilter.java:58)
at com.core.web.action.permission.UserAction.getUserInfo(UserAction.java:266)
at org.hibernate.collection.PersistentSet.iterator(PersistentSet.java:163)
at org.hibernate.collection.AbstractPersistentCollection.read(AbstractPersistentCollection.java:86)
at org.hibernate.collection.AbstractPersistentCollection.initialize(AbstractPersistentCollection.java:344)
at org.hibernate.impl.SessionImpl.initializeCollection(SessionImpl.java:1716)
at org.hibernate.event.def.DefaultInitializeCollectionEventListener.onInitializeCollection(DefaultInitializeCollectionEventListener.java:60)
at org.hibernate.persister.collection.AbstractCollectionPersister.initialize(AbstractCollectionPersister.java:565)
at org.hibernate.loader.collection.CollectionLoader.initialize(CollectionLoader.java:36)
at org.hibernate.loader.Loader.loadCollection(Loader.java:2001)
at org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:43)
at org.hibernate.exception.SQLStateConverter.convert(SQLStateConverter.java:74)

使用框架：JPA。网上搜的修改配置文件如下，可是还报错。

<?xml version="1.0" encoding="UTF-8"?>
<persistence version="1.0"
	xmlns="http://java.sun.com/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_1_0.xsd">
	<persistence-unit name="myPU" transaction-type="RESOURCE_LOCAL">
		<provider>org.hibernate.ejb.HibernatePersistence</provider>
		<properties>
			
			<property name="hibernate.connection.provider_class" value="org.hibernate.connection.C3P0ConnectionProvider"/>
 			
			<property name="hibernate.c3p0.max_size" value="30"/>
			<property name="hibernate.c3p0.min_size" value="5"/>
			<property name="hibernate.c3p0.timeout" value="1800"/>
			<property name="hibernate.c3p0.max_statements" value="50"/>
			<property name="hibernate.c3p0.idle_test_period" value="120"/>
			<property name="hibernate.c3p0.acquire_increment" value="1"/>
			<property name="hibernate.c3p0.validate" value="false"/>
			<!-- 
			<property name="hibernate.c3p0.provider_class" value="org.hibernate.connection.C3P0ConnectionProvider"/>
         	-->
         
			<property name="hibernate.dialect" value="org.hibernate.dialect.MySQLDialect"/> 
			<property name="hibernate.connection.driver_class" value="com.mysql.jdbc.Driver"/> 
			<property name="hibernate.connection.url" value="jdbc:mysql://127.0.0.1:3306/ljy?useUnicode=true&characterEncoding=UTF-8"/> 
			<property name="hibernate.connection.username" value="root"/> 
			<property name="hibernate.connection.password" value="1234"/>			
			
			<property name="hibernate.hbm2ddl.auto" value="update"/>
			<property name="hibernate.show_sql" value="false"/>
			<property name="hibernate.format_sql" value="false"/>

			<property name="hibernate.cache.use_second_level_cache" value="true"/>
			<property name="hibernate.cache.use_query_cache" value="false"/>
			<property name="hibernate.cache.provider_class" value="org.hibernate.cache.EhCacheProvider"/>

		</properties>
	</persistence-unit>
</persistence>