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;
/**
*这里是主要代码
**/
public class ConnPoolTest {

    private int init_count = 3;//连接池的初始值
    private int max_count = 6;//提供链接的最大值
    private int convert_count = 0;//链接的当前值
    LinkedList<Connection> list = new LinkedList<Connection>();

    // 创建连接
    public Connection createConnection() {
        Connection connection = JDBCUtils.getConnection();
        Connection proxycloseConnection = proxyCloseConnection(connection);
        return proxycloseConnection;
    }

    // 网链接池中添加连接
    public void connPool() {
        if (convert_count < init_count) {
            for (int i = 0; i < init_count; i++) {
                list.add(createConnection());
            }
        }
    }

    // 请求使用连接
    public Connection getConnection() {
        // 如果连接池中有
        if (list.size() > 0) {
            convert_count++;
            return list.removeFirst();
        }
        // 如果连接池没有,但是小于最大连接数
        if (convert_count < max_count) {
            convert_count++;
            return createConnection();
        }
        // 如果超出了最大连接数还在请求，抛出异常
        throw new RuntimeException("已经拿到最大连接数");
    }

    // 释放连接
    public void relaceseConnection(Connection connection) {
        // 如果连接数小于小于初始化的数目则放回连接池中
        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，来监听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执行");
                            list.addLast(connection);
                            System.out.println("end:放入连接池");
                        } 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("连接池中剩余的连接数:" + list.size());
        System.out.println("连接池中的连接数:" + convert_count);
    }

}