注意：使用裝飾者模式增強Connection的close方法

1. 測試部分

package com.it.jdbc.TestDataSoure;

import java.sql.Connection;
import java.sql.PreparedStatement;
import javax.management.RuntimeErrorException;
import org.junit.Test;
import com.it.jdbc.DataSoure.MyDataSoure;
import com.it.jdbc.utils.JDBCUtils_V3;

public class TestMyDataSoure {
    /**
     * 添加用戶
     * 使用改造Connection
     */
    @Test
    public void testAdduser1() {
    Connection conn = null;
    PreparedStatement pstmt = null;
    // 自定義連接池對象
    MyDataSoure datasoure = new MyDataSoure();
    try {
        // 從連接池獲得鏈接
        conn = datasoure.getConnection();
        String sql = "insert into use1 value(null,?,?)";
        pstmt =conn.prepareStatement(sql);
        pstmt.setString(1, "何一");
        pstmt.setString(2, "李二");
        int rows = pstmt.executeUpdate();
        if (rows > 0) {
            System.out.println("添加成功");
        } else {
            System.out.println("添加失敗");
        }
    } catch (Exception e) {
        throw new RuntimeException(e);
    } finally {
        JDBCUtils_V3.release(conn, pstmt, null);
    }
}
}

2.MyConnection

package com.it.jdbc.DataSoure;

import java.sql.Array;
import java.sql.Blob;
import java.sql.CallableStatement;
import java.sql.Clob;
import java.sql.Connection;
import java.sql.DatabaseMetaData;
import java.sql.NClob;
import java.sql.PreparedStatement;
import java.sql.SQLClientInfoException;
import java.sql.SQLException;
import java.sql.SQLWarning;
import java.sql.SQLXML;
import java.sql.Savepoint;
import java.sql.Statement;
import java.sql.Struct;
import java.util.LinkedList;
import java.util.Map;
import java.util.Properties;
//1，實現(xiàn)同一個接口
public class MyConnection implements Connection{
    //3,定義一個變量
    private Connection conn;
    private LinkedList<Connection> pool;
    //寫構(gòu)造方法(參數(shù)使用了面向?qū)ο?多態(tài))
    public MyConnection (Connection conn,LinkedList<Connection> pool){
        this.conn =conn;
        this.pool=pool;
    }
    //增強的方法
    @Override
    public void close() throws SQLException {
        // TODO Auto-generated method stub
        pool.add(conn);
    }
    @Override
    //此方法必須覆蓋，否則空指針異常 
        public PreparedStatement prepareStatement(String sql) throws SQLException {
        // TODO Auto-generated method stub
        return conn.prepareStatement(sql);
    }
}

3.MyDataSoure

package com.it.jdbc.DataSoure;

import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.SQLException;
import java.util.LinkedList;
import javax.sql.DataSource;
import com.it.jdbc.utils.JDBCUtils_V3;

public class MyDataSoure implements DataSource {
    // 1,創(chuàng)建一個容器，存儲Connection對象
    private static LinkedList<Connection> pool = new LinkedList<Connection>();
    // 2,創(chuàng)建5個鏈接放到容器中
    static {
        for (int i = 0; i < 5; i++) {
            Connection conn = JDBCUtils_V3.getConnection();
            MyConnection myconn= new MyConnection(conn, pool);
            pool.add(myconn);
        }
    }

    @Override
    public Connection getConnection() throws SQLException {
        Connection conn = null;
        // 3掸驱，使用前判斷
        if (pool.size() == 0) {
            // 4,添加鏈接
            for (int i = 0; i < 5; i++) {
                conn = JDBCUtils_V3.getConnection();
            //連接池中的自定義myconn
                MyConnection myconn= new MyConnection(conn, pool);
                pool.add(myconn);
            }
        }
        // 5,從連接池獲取一個鏈接對象Connection
        conn = pool.remove(0);
        return conn;
    }

    public void backConnection(Connection conn) {
        // 歸還連接池
        pool.add(conn);
    }


}