Question

为了连接到数据库，我在尝试使用资源行时使用了此命令，然后输入了PreparedStatement：

try(conn = C3P0DataSource.getInstance().getConnection()){
.
.//Prepared Statement
.
}catch(SQLException e){
}

我的C3P0DataSource类是：

import java.beans.PropertyVetoException;
import java.sql.Connection;
import java.sql.SQLException;
import javax.swing.JOptionPane;

import com.mchange.v2.c3p0.ComboPooledDataSource;

public class C3P0DataSource {
private static C3P0DataSource dataSource;
private ComboPooledDataSource comboPooledDataSource;

private C3P0DataSource() {
    try {
        comboPooledDataSource = new ComboPooledDataSource();
        comboPooledDataSource.setDriverClass("org.postgresql.Driver");
        comboPooledDataSource.setJdbcUrl("Server Address");
        comboPooledDataSource.setUser("My username");
        comboPooledDataSource.setPassword("My password");
        comboPooledDataSource.setMaxStatements( 180 ); 

        comboPooledDataSource.setMaxIdleTime(100);
    }catch (PropertyVetoException ex1) {
        JOptionPane.showMessageDialog(Main.splash_screen,
                "Missing PostgreSQL JDBC Driver",
                "Inane error",
                JOptionPane.ERROR_MESSAGE);
        System.exit(1);
    }
}

public static C3P0DataSource getInstance() {
    if (dataSource == null)
        dataSource = new C3P0DataSource();
    return dataSource;
}

public Connection getConnection() {
    Connection con = null;
    try {

        con = comboPooledDataSource.getConnection();
        if(con==null) {
            JOptionPane.showMessageDialog(Main.splash_screen,
                    "Connection couldn`t established...",
                    "Inane error",
                    JOptionPane.ERROR_MESSAGE);
            System.exit(1);
        }

    } catch (SQLException e) {
        JOptionPane.showMessageDialog(Main.splash_screen,
                "Connection couldn`t established...",
                "Inane error",
                JOptionPane.ERROR_MESSAGE);
        System.exit(1);
    }
    return con;
}

}

我正在使用这种方法通过VPN连接到服务器中的PostgreSQL数据库。当我有互联网连接并且VPN开启时，它可以正常工作。但是，当我有意关闭Internet连接或VPN观察正在发生的事情时，它进入无限循环，有很多例外：

（2018年8月13日，下午11:28:49 org.postgresql.Driver connect 严重：连接错误： org.postgresql.util.PSQLException：连接尝试失败。在org.postgresql.core.v3.ConnectionFactoryImpl.openConnectionImpl（ConnectionFactoryImpl.java:257）在org.postgresql.core.ConnectionFactory.openConnection（ConnectionFactory.java:49）在org.postgresql.jdbc.PgConnection。（PgConnection.java:195）在org.postgresql.Driver.makeConnection（Driver.java:452）在org.postgresql.Driver.connect（Driver.java:254）在com.mchange.v2.c3p0.DriverManagerDataSource.getConnection（DriverManagerDataSource.java:175）在com.mchange.v2.c3p0.WrapperConnectionPoolDataSource.getPooledConnection（WrapperConnectionPoolDataSource.java:220）在com.mchange.v2.c3p0.WrapperConnectionPoolDataSource.getPooledConnection（WrapperConnectionPoolDataSource.java:206）在com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool $ 1PooledConnectionResourcePoolManager.acquireResource（C3P0PooledConnectionPool.java:203）在com.mchange.v2.resourcepool.BasicResourcePool.doAcquire（BasicResourcePool.java:1138）在com.mchange.v2.resourcepool.BasicResourcePool.doAcquireAndDecrementPendingAcquiresWithinLockOnSuccess（BasicResourcePool.java:1125）中在com.mchange.v2.resourcepool.BasicResourcePool.access $ 700（BasicResourcePool.java:44）在com.mchange.v2.resourcepool.BasicResourcePool $ ScatteredAcquireTask.run（BasicResourcePool.java:1870）在com.mchange.v2.async.ThreadPoolAsynchronousRunner $ PoolThread.run（ThreadPoolAsynchronousRunner.java:696）造成原因：java.net.SocketTimeoutException：连接超时在java.base / java.net.PlainSocketImpl.socketConnect（本机方法）在java.base / java.net.AbstractPlainSocketImpl.doConnect（AbstractPlainSocketImpl.java:400）在java.base / java.net.AbstractPlainSocketImpl.connectToAddress（AbstractPlainSocketImpl.java:243）在java.base / java.net.AbstractPlainSocketImpl.connect（AbstractPlainSocketImpl.java:225）在java.base / java.net.SocksSocketImpl.connect（SocksSocketImpl.java:402）在java.base / java.net.Socket.connect（Socket.java:591）在org.postgresql.core.PGStream。（PGStream.java:69）在org.postgresql.core.v3.ConnectionFactoryImpl.openConnectionImpl（ConnectionFactoryImpl.java:156） ...还有13个）

直到我重新打开互联网连接。我的预期结果是在此过程结束时放置一个超时时间，并弹出上面显示的JOptionPane，然后退出。我该如何实现？

JAVA中的C3P0连接池

0 个答案: