MySqlデータベース接続プールのカスタム実装

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.Stack;

public class DbConnectPool {
    
    
	private String jdbcDeriver = "com.mysql.jdbc.Driver";
	private String url = "jdbc:mysql://127.0.0.1:3306/";
	private String username = "root";
	private String password = "201214600";
	private String dbname = "game";
	private Stack<Connection> freePool;
	private ArrayList<Connection> busyPool;
	private final int initCount = 10;
	private final int maxCount = 80;
	private int conCount = 0;
	private static final DbConnectPool dcp = new DbConnectPool();	//单例模式
	public static DbConnectPool GetInstance(){
    
    						//不可实例化，只能通过调用该方法获取连接池对象
		return dcp;
	}
	private DbConnectPool(){
    
    							//私有化的构造器
		loadDeriver();
		freePool = CreatePool();
		busyPool = new ArrayList<Connection>();
	}
	private void loadDeriver(){
    
    							//加载数据库驱动
	    try{
    
    
	    	Class.forName(jdbcDeriver) ;   
	    }catch(ClassNotFoundException e){
    
       
	    	System.out.println("找不到驱动程序类 ，加载驱动失败！");   
	    	e.printStackTrace() ;   
	    }
	}

	private Stack<Connection> CreatePool(){
    
    				//创建连接池，连接池用队列表示
		Stack<Connection> pool = new Stack<Connection>();
		for(int i = 0; i < initCount; i++){
    
    
			pool.push(createConnection());
		}
		conCount = initCount;
		return pool;
	}
	
	private synchronized Connection createConnection(){
    
    	//创建一个新的连接
		try{
    
    
			return DriverManager.getConnection(url + dbname + "?user=" + username + "&password=" + password 
						+ "&useUnicode=true&characterEncoding=gbk&autoReconnect=true&failOverReadOnly=false");
		}catch(SQLException se){
    
    
			System.out.println("数据库连接失败");
			se.printStackTrace();
		}
		return null;
	}
	public Connection GetConnection() throws SQLException{
    
    	//获取空闲连接的方法
		if(freePool == null){
    
    
			return null;
		}
		Connection con = getFreeConnection();
		int waitCount = 0;
		while(con == null && waitCount < 5){
    
    
			waitCount++;
			wait(100);
			con = getFreeConnection();
		}
//		System.out.println(conCount + "::" + freePool.size() + "::" + busyPool.size());
		return con;
	}
	private synchronized Connection getFreeConnection() throws SQLException{
    
    	//从连接池中获取空闲连接
		Connection con = null;
		if(freePool.isEmpty()){
    
    
			if(conCount < maxCount){
    
    
				con = createConnection();
				conCount++;
				busyPool.remove(con);
			}
		}else{
    
    
			con = freePool.pop();
			if(con == null || con.isClosed()){
    
    
				conCount--;
			}else{
    
    
				busyPool.add(con);
			}
		}
		return con;
	}
	public synchronized void FreeConnection(Connection con) throws SQLException{
    
    	//释放连接
		if(con == null){
    
    
			System.out.println("释放连接为空");
			return;
		}
		busyPool.remove(con);
		if(con.isClosed()){
    
    
			conCount--;
		}else{
    
    
			freePool.push(con);			
		}
	}
	private void wait(int mseconds){
    
    
		try {
    
    
			Thread.sleep(mseconds);
		} catch (InterruptedException e) {
    
    
			e.printStackTrace();
		}
	}
}