Java 连接关闭后不允许进行任何操作

No operations allowed after connection closed

提问by tuxx

I'm getting this error from a Java application:

我从 Java 应用程序收到此错误：

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!

The Java code:

Java代码：

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

The session factory:

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            throw new HibernateException("Transaction is no longer Active.");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            throw new HibernateException("Transaction is no longer Active.");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 and C3P0 settings:

休眠和 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>

Not sure how the connection can be still in use and this error thrown. What is causing this error?

不确定连接如何仍在使用中并抛出此错误。是什么导致了这个错误？

回答by Eric Leschinski

This Java method called executeQuery:

这个名为 executeQuery 的 Java 方法：

your_database_connection.createStatement().executeQuery(your_string_query);

will throw this Exception:

会抛出这个异常：

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

if you try to run it (executeQuery) after calling:

如果您在调用后尝试运行它 (executeQuery)：

your_database_connection.close()

What is happening

怎么了

Either you are trying to get a connection to the database and are not getting one, and are trying to run a query against it which fails. Or you got a connection which suffered some problem and became closed, and you tried to run another query through it.

要么您正在尝试与数据库建立连接但没有获得连接，并且正在尝试对其运行失败的查询。或者您的连接遇到问题并关闭，您尝试通过它运行另一个查询。

The solution

解决方案

Assuming you lost the connection from network problems or something that isn't your fault, then put the code that attempts the query in a try/catch block, and on error wait 10 seconds and reconnect to the database.

假设您因网络问题或不是您的错而失去连接，然后将尝试查询的代码放在 try/catch 块中，并在出错时等待 10 秒并重新连接到数据库。

回答by jerry_li

your idleConnectionTestPeriod is 240,it should less then the db waiting timeout value ,see the db config ,check the value is bigger than 240.

您的 idleConnectionTestPeriod 是 240，它应该小于数据库等待超时值，请参阅数据库配置，检查该值是否大于 240。