userdao.java

本系统是用NetBeans IDE 6.1所写

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package com.online.dao;

import com.online.pojo.User;
import java.sql.*;
import java.sql.Connection;
import java.sql.PreparedStatement;
import javax.sql.DataSource;
import javax.naming.Context;
import javax.naming.InitialContext;

/**
 *
 * @author Administrator
 */
public class UserDAO {
    private static final String GET_STMT = "SELECT * FROM EUSER WHERE username=?";
    
    private DataSource datasource;
    private ResultSet rs;
    User user=null;
    
    public UserDAO() {
        try {
            Context ctx = new InitialContext();
            datasource = (DataSource) ctx.lookup("jdbc/OnlineExamDB");
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
     public User getUs(String username) {
         Connection con = null;
         PreparedStatement ps = null;
        try {
        
            con = datasource.getConnection();
            
            ps = con.prepareStatement(GET_STMT);
            ps.setString(1, username);
           
            rs = ps.executeQuery(); 
            
         while(rs.next()){
            user=new User(rs.getInt("uid"),rs.getString("username"),rs.getString("password"));
        }
             
        } catch (SQLException se) {
            se.printStackTrace();
        } finally {
            if(ps != null) {
                try { ps.close(); } catch (Exception e) { e.printStackTrace(); }
            }
            if(con != null) {
                try { con.close(); } catch (Exception e) { e.printStackTrace(); }
            }
        }
        return user;
    }
}