dbmain.java

学生考勤管理系统————分为课程选择

/**
 * 
 */
package com.ccniit.kaoqin.db;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.SQLException;

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


/**
 * @author 邓从伟
 *
 */
public class DBMain 
{
	  private Connection con = null;
	/**
	 * 获得一个PreparedStatement的对象
	 * @param sqlStr
	 * @return pst
	 * @throws ClassNotFoundException
	 * @throws SQLException
	 * @throws NamingException 
	 * @throws NamingException 
	 */
	public PreparedStatement getPreparedStatement(String sqlStr) throws ClassNotFoundException, SQLException
	{
        PreparedStatement pst = null;   
		
		Context initContext =null;
		Context envContext =null;
		DataSource ds=null;
		try {
		
		//数据库的连接池
			initContext= new InitialContext();
			envContext  = (Context)initContext.lookup("java:/comp/env");
			 ds = (DataSource)envContext.lookup("jdbc/kaoqindb");

			if(con==null||con.isClosed()){
			 con =ds.getConnection();
			
				
			}
			pst =con.prepareStatement(sqlStr);
			
		} catch (NamingException e) {
			// TODO 自动生成 catch 块
			e.printStackTrace();
		}
		
		
		return pst;
	}
	/**
	 * 关闭数据库连接
	 * @throws SQLException
	 */
	public void releaes() throws SQLException
	{
		if(con != null && !con.isClosed())
		{
			con.close();
		
		}
		
	}
	
	
	

	
	
}