package com.pool.cn;

import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;
import java.sql.Connection;
import java.sql.SQLException;
import java.util.LinkedList;

import org.junit.Test;

import com.utils.cn.JDBCUtils;
/**
*這裏是主要代碼
**/
public class
 
 ConnPoolTest {

    private int init_count = 3;//連接池的初始值
    private int max_count = 6;//提供鏈接的最大值
    private int convert_count = 0;//鏈接的當前值
    LinkedList<Connection> list = new LinkedList<Connection>();

    // 創建連接
    public Connection createConnection() {
        Connection connection = JDBCUtils.getConnection();
        Connection proxycloseConnection 
 
= proxyCloseConnection(connection);
        return proxycloseConnection;
    }

    // 網鏈接池中添加連接
    public void connPool() {
        if (convert_count < init_count) {
            for (int i = 0; i < init_count; i++) {
                list.add(createConnection());
            }
        }
    }

    
 
// 請求使用連接
    public Connection getConnection() {
        // 如果連接池中有
        if (list.size() > 0) {
            convert_count++;
            return list.removeFirst();
        }
        // 如果連接池沒有,但是小於最大連接數
        if (convert_count < max_count) {
            convert_count++;
            return createConnection();
        }
        // 如果超出了最大連接數還在請求，拋出異常
        throw new RuntimeException("已經拿到最大連接數");
    }

    // 釋放連接
    public void relaceseConnection(Connection connection) {
        // 如果連接數小於小於初始化的數目則放回連接池中
        if (list.size() < init_count) {
            convert_count--;
            list.add(connection);
        } else {
            try {
                connection.close();
                convert_count--;
            } catch (SQLException e) {
                // TODO Auto-generated catch block
                throw new RuntimeException(e);
            }
        }
    }

    // 使用代理，來監聽Connection中的方法
    public Connection proxyCloseConnection(Connection connection) {
        Connection proxy = (Connection) Proxy.newProxyInstance(Connection.class.getClassLoader(),
                new Class[] { Connection.class }, new InvocationHandler() {
                    @Override
                    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
                        Object result = null;
                        String name = method.getName();
                        if ("close".equals(name)) {
                            System.out.println("begin:close執行");
                            list.addLast(connection);
                            System.out.println("end:放入連接池");
                        } else {
                            result = method.invoke(connection, args);
                        }
                        return result;
                    }
                });
        return proxy;
    }

    @Test
    public void testName() throws Exception {
        connPool();
        Connection connection1 = getConnection();
        getConnection();
        getConnection();
        getConnection();
        getConnection();
        getConnection();
//        relaceseConnection(connection1);
        connection1.close();
        getConnection();
        System.out.println("連接池中剩余的連接數:" + list.size());
        System.out.println("連接池中的連接數:" + convert_count);
    }

}

proxy代理對鏈接Connection的處理