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<%@ page contentType="text/html;charset=UTF-8" language="java" %>


    


登录页面

    

    

    

2.然后就会去servlet层找user?method=login方法

package cn.kgc.javaweb.servlet;

import cn.kgc.javaweb.entity.Student;
import com.alibaba.fastjson.JSON;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.Date;
import java.util.HashMap;


@WebServlet("/user")
public class UserServlet extends BaseServlet {

    // 登录
    protected void login(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        String username = req.getParameter("username");
        String password = req.getParameter("password");

        if ("admin".equals(username) && "123456".equals(password)) {// 登录成功 跳转到主页

            ArrayList students = new ArrayList<>();

            // 把十条数据放进集合中 在把集合放到session里 index去session拿值回显
            for (int i = 0; i < 10; i++) {
                Student student = Student.builder().stuNo("11" + i).stuName("郭新桥").age(20 + i).birth(new Date()).build();
                students.add(student);
            }
            HttpSession session = req.getSession();
            session.setAttribute("students",students);

            resp.sendRedirect(req.getContextPath() + "/index.jsp");
            
        } else {// 登陆失败 跳转到login 并附带错误信息
            resp.setContentType("application/json;charset=utf-8");
            PrintWriter writer = resp.getWriter();
            writer.write("用户名或密码错误！");
            writer.close();
        }
    }
}

3.最后跳转到主页回显用户的数据

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  User: 小保底不歪
  Date: 2022/6/23
  Time: 15:50
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<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<%@taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<%@ taglib prefix="fmt" uri="http://java.sun.com/jsp/jstl/fmt" %>


    


主页

        

    

        
学号
        
姓名
        
年龄
        
生日
    

    

            
${student.stuNo}
            
${student.stuName}
            
${student.age}
            

                
            
        
    

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  User: 小保底不歪
  Date: 2022/6/23
  Time: 15:17
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<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<%@taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>


    
    


注册页面

    

    

    



    

2.底层代码

// 检查用户名是否合法
    protected void checkUserName(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        String username = req.getParameter("username");
        HashMap map = new HashMap<>();
        if("admin".equals(username)){// 不合法
            map.put("code",500);
            map.put("msg","用户名已被占用");
        }else{// 合法
            map.put("code",200);
            map.put("msg","用户名可用");
        }

        // 把信息回显给前端页面
        resp.setContentType("application/json;charset=utf-8");
        PrintWriter writer = resp.getWriter();
        String s = JSON.toJSONString(map);
        writer.write(s);
        writer.close();
    }