1 package cn.login.service;
 2 
 3 import cn.login.bean.User;
 4 import cn.login.imp.UserImp;
 5 
 6 public class LoginService {
 7     //这是我的业务层
 8     // 调用dao包中的方法
 9     private UserImp dao;
10 
11     public User login(User u) {
12         User existu = dao.denlu1(u.getUsername(), u.getPassword());
13         if (existu == null) {
14             throw new RuntimeException("没有该用户");
15         }
16         if (!existu.getPassword().equals(u.getPassword())) {
17             throw new RuntimeException("密码不正确");
18         }
19 
20         return existu;
21 
22     }
23 }

package cn.login.web;

import java.io.IOException;
import java.io.PrintWriter;
import java.lang.reflect.InvocationTargetException;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.commons.beanutils.BeanUtils;

import cn.login.bean.User;
import cn.login.service.LoginService;

public class LoginServlet extends HttpServlet {
    private LoginService dao;
    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
            doPost(request, response);
    }

    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        String path = request.getContextPath();
        String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
        
        //1.处理中文乱码这是我的web层
        request.setCharacterEncoding("utf-8");
        response.setCharacterEncoding("utf-8");
        //2.封装数据以及对数据进行强转
        User u = new User();        
        try {
            BeanUtils.populate(u, request.getParameterMap());
        } catch (IllegalAccessException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (InvocationTargetException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        //调用service
        User existu = null;
        //调用dao包中的方法
        try {
            existu =dao.login(u);
        } catch (Exception e) {
            e.printStackTrace();
            request.setAttribute("error", e.getMessage());
            request.getRequestDispatcher("/index.jsp").forward(request, response);
            return;
        }
        // 4.向session中加入登录标识
        request.getSession().setAttribute("user", existu);
    
    }

}