Question

我从Java应用程序中收到此错误：

com.mchange.v2.c3p0.impl.NewPooledConnection - [c3p0] Another 
error has occurred [     
com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: 
No operations allowed after connection closed. ] which will not be 
reported to listeners!

Java代码：

try {
    sessionFactory.beginTransaction();
    //...
    sessionFactory.commitTransaction();
} catch (Exception e) {
    sessionFactory.rollbackTransaction();
    throw new RuntimeException(e);
}

会话工厂：

try {
    sessionFactory.beginTransaction();
    ...
    sessionFactory.commitTransaction();
} catch (Exception e) {
    sessionFactory.rollbackTransaction();
    throw new RuntimeException(e);
}

public Transaction beginTransaction() throws HibernateException {
    try {
        return sessionFactory.getCurrentSession().beginTransaction();
    } catch (HibernateException hex) {
        LOG.error(String.format("Unable to start database transaction due to exception: %s.", ExceptionUtils.getRootCauseMessage(hex)));
        throw hex;
    }
}

public void commitTransaction() throws HibernateException {
    LOG.debug("Committing database transaction.");
    try {
        if (sessionFactory.getCurrentSession().getTransaction().isActive()) {
            sessionFactory.getCurrentSession().getTransaction().commit();
        } else {
            throw new HibernateException("Transaction is no longer Active.");
        }
    } catch (HibernateException hex) {
        LOG.error(String.format("Unable to commit due to exception: %s.", ExceptionUtils.getRootCauseMessage(hex)));
        throw hex;
    }
}

public void rollbackTransaction() throws HibernateException {
    LOG.debug("Trying to rollback database transaction after exception.");
    Session session = sessionFactory.getCurrentSession();
    try {
        if (session.getTransaction().isActive()) {
            session.getTransaction().rollback();
        } else {
            throw new HibernateException("Transaction is no longer Active.");
        }
    } catch (HibernateException hex) {
        LOG.error(String.format("Unable to rollback due to exception: %s.", ExceptionUtils.getRootCauseMessage(hex)));
        throw hex;
    } finally {
        if (session.isOpen()) {
            session.close();
        }
    }
}

Hibernate和C3P0设置：

<prop key="hibernate.connection.provider_class">org.hibernate.connection.C3P0ConnectionProvider</prop>
<prop key="hibernate.connection.driver_class">com.mysql.jdbc.Driver</prop>

<prop key="hibernate.dialect">org.hibernate.dialect.MySQLDialect</prop>
<prop key="hibernate.show_sql">false</prop>
<prop key="hibernate.current_session_context_class">thread</prop>
<prop key="hibernate.transaction.factory_class">org.hibernate.transaction.JDBCTransactionFactory</prop>
<prop key="hibernate.jdbc.batch_size">20</prop>
<prop key="hibernate.order_inserts">true</prop>
<prop key="hibernate.order_updates">true</prop>
<prop key="hibernate.c3p0.timeout">1800 <!-- seconds --></prop>
<prop key="hibernate.c3p0.min_size">4</prop>
<prop key="hibernate.c3p0.max_size">35</prop>
<prop key="hibernate.c3p0.idle_test_period">240 <!-- seconds --></prop>
<prop key="hibernate.c3p0.acquire_increment">4</prop>
<prop key="hibernate.c3p0.max_statements">0</prop>
<prop key="hibernate.c3p0.preferredTestQuery">SELECT 1</prop>
<prop key="c3p0.testConnectionOnCheckout">true</prop>
<prop key="hibernate.connection.oracle.jdbc.ReadTimeout">60000 <!-- milliseconds --></prop>

不确定连接如何仍在使用中并抛出此错误。导致此错误的原因是什么？

Answer 1

这个名为executeQuery的Java方法：

your_database_connection.createStatement().executeQuery(your_string_query);

将抛出此异常：

com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: 
No operations allowed after connection closed.

如果你在调用后尝试运行它（executeQuery）：

your_database_connection.close()

发生了什么

您要么尝试获取与数据库的连接而又没有获得连接，并且正在尝试对其进行查询而失败。或者你有一个连接遇到了一些问题并且关闭了，你试图通过它运行另一个查询。

解决方案

假设您丢失了网络问题或不是您的错误的连接，请将尝试查询的代码放在try / catch块中，并在出现错误时等待10秒并重新连接到数据库。

Answer 2

你的idleConnectionTestPeriod是240，它应该小于db waiting timeout值，参见db config，检查值是否大于240。

连接关闭后不允许任何操作

2 个答案: