package huc.blog.util;

import java.sql.Connection;

import javax.naming.Context;
import javax.naming.InitialContext;
import javax.naming.NamingException;
import javax.sql.DataSource;

public class DB {

	private Connection conn = null;
	
	private DataSource ds = null;

	private String jdbcName = "jdbc/blog";

	private Context ctx = null;
	
	private StringBuffer jdbcStr = new StringBuffer();
	
	public DB(){
		jdbcStr.append("java:comp/env/");
		jdbcStr.append(this.jdbcName);
		
		this.init();
	}
	
	public DB(String jdbcName){
		jdbcStr.append("java:comp/env/");
		jdbcStr.append(jdbcName);
		
		this.init();
	}
		
	/**
	 * 獲得打開的Connection
	 * 
	 * @return
	 */
	public Connection getConnection() {
		try {
			conn = ds.getConnection();
		} catch (Exception e) {
			System.out.println("connect db error:" + e.getMessage());
			return null;
		}

		return conn;
	}
	
	/**
	 * 初始化ctx和ds
	 *
	 */
	public void init(){
		try {
			ctx = new InitialContext();
			if (ctx == null)
				throw new Exception("沒有匹配的環境");
			ds = (DataSource) ctx.lookup(jdbcStr.toString());
			if (ds == null)
				throw new Exception("沒有匹配數據庫");
		} catch (NamingException e) {
			e.printStackTrace();
		} catch (Exception e) {
			e.printStackTrace();
		}
	}
}