userdaoimpl.java

一个公司管理系统,用简单的htmlt要servlet做的,有增.查.改功能.适合同学学习交流.

package com.tarena.dao;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;

import com.tarena.util.JdbcUtils;
import com.tarena.vo.Users;
/**
 * 
 * @author dong xuyuan
 *
 */
public class UserDaoImpl implements UserDao {

	public Users checkUserValid(String username, String password) {
		if(username == null || password == null) {
			return null;
		}
		
		//定义返回变量
		Users user = null;
		
		Connection conn = null;
		PreparedStatement pstmt = null;
		ResultSet rs = null;
		StringBuffer sql = new StringBuffer("select * from users where username=? and password=?");
		
		try {
			conn = JdbcUtils.getConnection();
			pstmt = conn.prepareStatement(sql.toString());
			pstmt.setString(1, username);
			pstmt.setString(2, password);
			rs = pstmt.executeQuery();
			if(rs.next()) {
				user = new Users();
				user.setUsername(rs.getString("username"));
				user.setRole(rs.getString("role"));
			}
		} catch (Exception e) {
			e.printStackTrace();
		} finally {
			JdbcUtils.close(rs);
			JdbcUtils.close(pstmt);
			JdbcUtils.close(conn);
		}
		
		
		return user;
	}

}