package demo;

import java.sql.*;
import java.util.*;
import java.io.*;

/**
	由于該連接工廠具有重用性，為了避免資源浪費
	因此在這里使用單例模式。單例模式的前提是構
	造器私有，通過一個靜態方法來控制實例創建的
	個數。
*/

public class ConnectionFactory{
	private static ConnectionFactory instance;
	private static String key = "key";

	private ConnectionFactory(){}

	public static ConnectionFactory getInstance(){
		if(instance == null){
			synchronized(key){
				if(instance == null){
					instance = new ConnectionFactory();
				}
			}
		}
		return instance;
	}
	public Connection getConnection()throws Exception{
		InputStream is = getClass().getResourceAsStream("/jdbc.properties");
		Properties pro = new Properties();
		pro.load(is);
		//注冊JDBC驅動
		Class.forName(pro.getProperty("driver"));
		return DriverManager.getConnection(pro.getProperty("url"),pro.getProperty("username"),pro.getProperty("password"));
	}
}