package com.gd.jdbc.impl;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Set;

import com.gd.jdbc.DbConnectionPool;

public class GdDbConnectionPool implements DbConnectionPool {
	private String DB_DRIVER = "com.mysql.jdbc.Driver";
	private String DB_User = "root";
	private String DB_PASSWD = "root";
	private String DATASRC_URL = "jdbc:mysql://localhost/myApp";
	static final int defaultMaxConnections = 10;//默認的連接池的大小
	private List freeConnections;//存放目前空閑的連接,空閑池
	private Map busyConnections;//存放目前正在使用的連接,繁忙池
	private int maxConnections;//設(shè)定連接池的大小
	/**
	 * 構(gòu)造函數(shù)
	 * @param numConnections
	 */
	public GdDbConnectionPool (int numConnections) {
		maxConnections = numConnections;
		freeConnections = null;
		busyConnections = null;		
	}
	/**
	 * 構(gòu)造函數(shù)
	 */
	public GdDbConnectionPool () {
		maxConnections = defaultMaxConnections;
		freeConnections = null;
		busyConnections = null;
	}
	/* (non-Javadoc)
	 * @see com.gd.jdbc.DbConnectionPool#destroyConnPool()
	 */
	public void destroyConnPool() throws SQLException {
		//假如還有正在使用的連接
		if (busyConnections != null) {
			Set set = busyConnections.entrySet();
			Iterator iterator = set.iterator();
			//銷毀正在使用的連接
			while (iterator.hasNext()) {
				Map.Entry map = (Map.Entry)iterator.next();
				Connection conn = (Connection)map.getValue();
				conn.close();
			}
			busyConnections = null;
		}
		//假如還有空閑的連接
		if (freeConnections != null) {
			//銷毀空閑的連接
			for (int i = 0; freeConnections.size() > i; i++) {
				Connection conn = (Connection)freeConnections.get(i);
				conn.close();
			}
			freeConnections = null;
		}
	}

	/* (non-Javadoc)
	 * @see com.gd.jdbc.DbConnectionPool#getConnection()
	 */
	public synchronized Connection getConnection() throws SQLException {
		if (freeConnections == null)
			throw new SQLException("連接池還沒有創(chuàng)建");
		try {
			//表示暫時沒有空閑的連接
			if (freeConnections.size() == 0)
				wait();
		} catch(InterruptedException e) {
			e.printStackTrace();
		}
		//獲取空閑池的連接
		Connection conn = (Connection)freeConnections.get(0);
	
		freeConnections.remove(0);//在空閑池里銷毀已經(jīng)獲取的連接
		busyConnections.put(Thread.currentThread(), conn);//將已經(jīng)獲取的連接放在繁忙池里
		return conn;
	}
	
	/* (non-Javadoc)
	 * @see com.gd.jdbc.DbConnectionPool#initConnPool()
	 */
	public void initConnPool() throws SQLException {
		try {
			freeConnections = new ArrayList(maxConnections);
			busyConnections = new HashMap(maxConnections);
			//創(chuàng)建連接,并放在連接池中
			Class.forName(DB_DRIVER);
            //conn = DriverManager.getConnection(DATASRC_URL, DB_User, DB_PASSWD);
			//GdDbConnection con = new GdDbConnection(this);
			for (int i = 0; i < maxConnections; i++) {
				freeConnections.add(DriverManager.getConnection(DATASRC_URL, DB_User, DB_PASSWD));				
			}
		} catch (Exception e) {
			freeConnections = null;
			busyConnections = null;
			throw new SQLException(e.toString());
		}
	}

	/* (non-Javadoc)
	 * @see com.gd.jdbc.DbConnectionPool#returnConnection()
	 */
	public synchronized void returnConnection() throws SQLException {
		//從繁忙池中銷毀已經(jīng)返回的連接
		Connection conn = (Connection)busyConnections.get(Thread.currentThread());	
		if (conn == null) 
			throw new SQLException("沒有發(fā)現(xiàn)繁忙池中有連接");
		busyConnections.remove(Thread.currentThread());
		//將已經(jīng)返回的連接重新放回空閑池中
		freeConnections.add(conn);
		notify();
	}

	/* (non-Javadoc)
	 * @see com.gd.jdbc.DbConnectionPool#setConnWitch(java.lang.String)
	 */
	public void setConnWitch(String onOrOff) throws Exception {
		try {
			//假如為ON,則表示初始化連接池
			if ("ON".equalsIgnoreCase(onOrOff)) {
				initConnPool();
			//假如為OFF,則表示銷毀連接池
			} else if ("OFF".equalsIgnoreCase(onOrOff)) 
				destroyConnPool();
		} catch (Exception e) {
			e.printStackTrace();
		}
	}

	/* (non-Javadoc)
	 * @see com.gd.jdbc.DbConnectionPool#setMaxConns(int)
	 */
	public void setMaxConns(int numConnections) {
		maxConnections = numConnections;
	}

}