DAO设计模式实现登陆注册查询

package com.dao;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.util.ArrayList;
import java.util.List;

import com.db.DB;
import com.user.Users;

public class UserDao implements UserI {

	DB db = new DB();
	Connection conn;

	// 登录
	public boolean loginConn(Users user) throws Exception {
		// TODO Auto-generated method stub
		conn = db.getConn();
		String sql = "select * from users_table where db_user = ? and db_password = ?";
		PreparedStatement ps = conn.prepareStatement(sql);
		ps.setString(1, user.getDb_user());
		ps.setString(2, user.getDb_password());
		ResultSet rs = ps.executeQuery();
		boolean flag = rs.next();
		rs.close();
		ps.close();
		db.closeConn();
		return flag;
	}

	// 注册
	public int insertData(Users user) throws Exception {
		// TODO Auto-generated method stub
		conn = db.getConn();
		String sql = "insert into users_table(db_user,db_password) VALUES (?,?);";
		PreparedStatement ps = conn.prepareStatement(sql);
		ps.setString(1, user.getDb_user());
		ps.setString(2, user.getDb_password());
		int a = ps.executeUpdate();
		ps.close();
		db.closeConn();
		return a;
	}

	// 查询
	public List
 
   getAllData() throws Exception {
		// TODO Auto-generated method stub
		conn = db.getConn();
		String sql = "select * from users_table";
		PreparedStatement ps = conn.prepareStatement(sql);
		ResultSet rs = ps.executeQuery();
		List
  
    list = new ArrayList(); while (rs.next()) { Users u = new Users(); u.setDb_id(rs.getInt(1)); u.setDb_user(rs.getString(2)); u.setDb_password(rs.getString(3)); list.add(u); } rs.close(); ps.close(); db.closeConn(); return list; } public static void main(String[] args) { UserI i = new UserDao(); Users u = new Users(); // 测试登录 u.setDb_user("D_nice"); u.setDb_password("487561"); try { boolean flag = i.loginConn(u); //返回true登录成功 返回false登录失败 System.out.println("登录" + flag); } catch (Exception e) { e.printStackTrace(); } //测试注册 try { Users user = new Users(); user.setDb_user("first"); user.setDb_password("147258"); int a = i.insertData(user); if(a>0){ System.out.println("注册成功"); }else{ System.out.println("注册失败"); } } catch (Exception e) { // TODO Auto-generated catch block e.printStackTrace(); } //测试查询 try { List
   
     list = i.getAllData(); for (int a = 0; a < list.size(); a++) { Users user = new Users(); user = list.get(a); System.out.println("查询结果如下："); System.out.println("ID:" + user.getDb_id() + "USER:" + user.getDb_user() + "PASSWORD:" + user.getDb_password()); } } catch (Exception e) { // TODO Auto-generated catch block e.printStackTrace(); } } }