package com.cqkj.controller;

import java.io.IOException;
import java.sql.ResultSet;
import java.sql.SQLException;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

import com.alibaba.fastjson.JSON;
import com.cqkj.bean.User;
import com.cqkj.services.UserService;
import com.cqkj.utils.DruidUtil;
import com.cqkj.utils.ResultMap;



@WebServlet("/user")
public class UserServlet extends BaseServlet{
    //servlet是什么？     哪个类继承了HttpServlet，那么这个类就不再是类而是servlet
    ResultMap resultMap = new ResultMap();
    UserService userService = new UserService();
    
    public String login(HttpServletRequest req, HttpServletResponse resp) {
        try {
            
            String username = req.getParameter("username");
            String password = req.getParameter("password");
            //调用userService业务逻辑层
            User user = userService.login(username,password);
            HttpSession session = req.getSession();
            session.setAttribute("user",user);
            resultMap.setStatus(true);
        } catch (Exception e) {
            resultMap.setStatus(false);
            resultMap.setMessage(e.getMessage());
        }
        
        String jsonStr = JSON.toJSONString(resultMap);
        return jsonStr;
    }
    
    public String selectAllUser(HttpServletRequest req, HttpServletResponse resp) {
        return "";
    }
}

package com.cqkj.services;

import java.sql.ResultSet;
import java.sql.SQLException;

import com.cqkj.bean.User;
import com.cqkj.dao.UserDao;
import com.cqkj.utils.DruidUtil;

public class UserService {//业务逻辑层

    UserDao userDao = new UserDao();
    
    public User login(String username,String password) throws SQLException {
        if(username.equals("")) {
            throw new RuntimeException("用户名不能为空！");
        }
        if(password.equals("")) {
            throw new RuntimeException("密码不能为空！");
        }
　　　　　//调用数据处理层
        User user = userDao.login(username, password);
        if(user == null) {
            throw new RuntimeException("用户名或密码输入有误！");
        }
        return user;
    }
}

import com.cqkj.utils.DruidUtil;

public class UserDao {//数据访问层
    
    
    public User login(String username,String password) throws SQLException {
        String sql = "select * from user where username = ? and password = ?";
        Object[] obj = {username,password};
        ResultSet rs = DruidUtil.query(sql, obj);
        User user = null;
        if(rs.next()) {
            user = new User();
            user.setUsername(rs.getString(1));
            user.setPassword(rs.getString(2));
            user.setName(rs.getString(3));
            user.setTel(rs.getString(4));
            user.setHeadImg(rs.getString(5));
            user.setType(rs.getInt(6));
        }
        return user;
    }

}