Question

我正在开发一个涉及MySQL数据库的学校项目。我们遇到了一个问题，当我们尝试连接到我们的服务器时，我们收到以下错误：

Severe:   Exception while deploying the app [FrienDB-Server]
Severe:   Exception during lifecycle processing
org.glassfish.deployment.common.DeploymentException: Exception [EclipseLink-4002] (Eclipse Persistence Services - 2.5.2.v20140319-9ad6abd): org.eclipse.persistence.exceptions.DatabaseException
Internal Exception: java.sql.SQLException: Error in allocating a connection. Cause: Connection could not be allocated because: User nwong already has more than 'max_user_connections' active connections

我们正在使用我们的学校SQL服务器，因此我们无权更改最大连接数。我试过杀死MySQL Workbench上的连接，但这不起作用。我们如何解决这个问题？

这是我的DatabaseConnection类

package friendb.server.util;
import java.util.Map;
import java.util.HashMap;
import org.eclipse.persistence.config.PersistenceUnitProperties;
import javax.persistence.EntityManagerFactory;
import javax.persistence.EntityManager;
import javax.persistence.Persistence;

/**
 * Utility class for database connections.
 * @author Evan Guby
 */
public final class DatabaseConnection
{

    private static final String PERSISTENCE_UNIT_NAME = "FrienDB";

    private static Map PROPERTIES = new HashMap();
    private static final String USERNAME = "nwong";
    private static final String PASSWORD = "108857304";

    /**
     * Creates and returns an entity manager connected to the persistence unit.
     * @return 
     */
    public static EntityManager getEntityManager()
    {
        PROPERTIES.put(PersistenceUnitProperties.JDBC_USER, USERNAME);
        PROPERTIES.put(PersistenceUnitProperties.JDBC_PASSWORD, PASSWORD);
        EntityManagerFactory emf =
                Persistence.createEntityManagerFactory(PERSISTENCE_UNIT_NAME, PROPERTIES);

        return emf.createEntityManager();
    }
}

在我尝试通过服务器从我们的客户端访问数据库中的某些内容时，它运行的极少数情况下我收到此错误：

Caused by: javax.transaction.xa.XAException: com.sun.appserv.connectors.internal.api.PoolingException: javax.resource.spi.LocalTransactionException: Communications link failure
The last packet successfully received from the server was 1,575,262 milliseconds ago.  The last packet sent successfully to the server was 0 milliseconds ago.

MySQL Max Connections错误：用户已有超过'max_user_connections'的活动连接

0 个答案: