com.mysql.jdbc.exceptions.jdbc4.CommunicationsException：通信链接失败6

Question

在日志中，我收到以下异常。会有什么可能的原因呢？ 应用程序有Spring 3.1，hibernate 3.6.9和最新的mysql。

 11:54:25,158 ERROR LoginController:152 - org.springframework.transaction.CannotCreateTransactionException: Could not open JPA EntityManager for transaction; nested exception is javax.persistence.PersistenceException: org.hibernate.TransactionException: JDBC begin failed: 
      at org.springframework.orm.jpa.JpaTransactionManager.doBegin(JpaTransactionManager.java:427) 
      at org.springframework.transaction.support.AbstractPlatformTransactionManager.getTransaction(AbstractPlatformTransactionManager.java:371) 
      at org.springframework.transaction.interceptor.TransactionAspectSupport.createTransactionIfNecessary(TransactionAspectSupport.java:335) 
      at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:105) 
      at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172) 
      at org.springframework.aop.framework.Cglib2AopProxy$DynamicAdvisedInterceptor.intercept(Cglib2AopProxy.java:622) 
      ..... 
      at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1110) 
      at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:603) 
      at java.lang.Thread.run(Thread.java:722) 
     Caused by: javax.persistence.PersistenceException: org.hibernate.TransactionException: JDBC begin failed: 
      at org.hibernate.ejb.AbstractEntityManagerImpl.convert(AbstractEntityManagerImpl.java:1215) 
      at org.hibernate.ejb.AbstractEntityManagerImpl.convert(AbstractEntityManagerImpl.java:1148) 
      at org.hibernate.ejb.AbstractEntityManagerImpl.throwPersistenceException(AbstractEntityManagerImpl.java:1225) 
      at org.hibernate.ejb.TransactionImpl.begin(TransactionImpl.java:63) 
      at org.springframework.orm.jpa.DefaultJpaDialect.beginTransaction(DefaultJpaDialect.java:70) 
      at org.springframework.orm.jpa.JpaTransactionManager.doBegin(JpaTransactionManager.java:377) 
      ... 50 more 
     Caused by: org.hibernate.TransactionException: JDBC begin failed: 
      at org.hibernate.transaction.JDBCTransaction.begin(JDBCTransaction.java:92) 
      at org.hibernate.impl.SessionImpl.beginTransaction(SessionImpl.java:1473) 
      at org.hibernate.ejb.TransactionImpl.begin(TransactionImpl.java:60) 
      ... 52 more 
     Caused by: com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure 

Answer 1

在persistance.xml中实施连接池（C3PO）后解决

Answer 2

看起来你失去了你的MySQL连接。这可能是网络问题或MySQL方面的问题。