package com.mysql.jdbc;

import java.io.InputStream;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.Properties;

import javax.sql.DataSource;

import org.apache.commons.dbcp.BasicDataSourceFactory;

public class Connection_Mysql {
	private static DataSource ds;
	private static ThreadLocal<Connection> tl = new ThreadLocal<Connection>();
	private static Properties props = new Properties();
	//加载类时，实行静态代码块
	static {
		try {
			InputStream in = Connection_Mysql.class.getClassLoader().getResourceAsStream
					("com/mysql/jdbc/db_MySql.properties");
			props.load(in);
			//通过配置文件创建连接池
			ds = BasicDataSourceFactory.createDataSource(props);
		} catch(Exception e) {
			e.printStackTrace();
			System.out.println("加载配置文件失败");
		}
	}
	
	public static Connection getConnection() throws SQLException {
		Connection conn = tl.get();
		if(conn == null) {
			conn = ds.getConnection();
			tl.set(conn);
		}	
		return conn;
	}
	
	public static String getObject(String key) {
		return props.getProperty(key);
	}
	public static void close() throws SQLException {
		Connection conn = tl.get();
		tl.set(null);
		if(conn != null && !conn.isClosed()) {
			conn.close();
		}
	}
	
	public static void main(String[] args) throws SQLException {
		Connection conn = getConnection();
		String sql = "select * from test";
		PreparedStatement ps = conn.prepareStatement(sql);
		ResultSet rs = ps.executeQuery();
		while(rs.next()) {
			System.out.println(rs.getString("name") +"\t"+ rs.getInt("id"));
		}
	}
}