实现用户修改[较为繁琐]

UpdateQueryServlet

package Servlet;

import Bean.User;
import Dao.UserDao;

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 java.io.IOException;

@WebServlet("/UpdateQueryServlet")
public class UpdateQueryServlet extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //1、获取数据
        String id = request.getParameter("uid");
        User user=new UserDao().getByID(Integer.parseInt(id));
//        2、并把数据存入域中
        request.setAttribute("user",user);
//        3、跳转至修改页面update.jsp
        request.getRequestDispatcher("/update.jsp").forward(request,response);
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doPost(request, response);
    }
}

updata.jsp

<%--
  Created by IntelliJ IDEA.
  User: Administrator
  Date: 2021/4/27
  Time: 8:57
  To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Title</title>
</head>
<body>
<form  action="/UpdateSubmitServlet" method="post">
    <input type="hidden" name="id"value="${user.id}"/><br>
    用户名：<input type="text" name="username" value="${user.username}" /><br>
    密码：<input type="password" name="password" value="${user.password}" /><br>
    邮箱：<input type="text" name="email" value="${user.email}" /><br>
    生日：<input type="date" name="birthday" value="${user.birthday}" /><br>

    <input type="submit" value="修改">
</form>
</body>
</html>

UpdateSubmitServlet

package Servlet;

import Bean.User;
import Dao.UserDao;
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 java.io.IOException;
import java.io.PrintWriter;
import java.text.ParseException;
import java.text.SimpleDateFormat;

@WebServlet("/UpdateSubmitServlet")
public class UpdateSubmitServlet extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        response.setContentType("text/html;charset=utf-8");
        request.setCharacterEncoding("utf-8");
        PrintWriter out=response.getWriter();
//        =====分割线=====
//          获取参数值
        String id=request.getParameter("id");
        String name=request.getParameter("username");
        String password=request.getParameter("password");
        String email=request.getParameter("email");
        String birthday=request.getParameter("birthday");
//        封装Bean对象
        User user = new User();
        user.setId(Integer.parseInt(id));
        user.setName(name);
        user.setPassword(password);
        user.setEmail(email);
        try{
            user.setBirthday(new SimpleDateFormat("yyyy-MM-dd").parse(birthday));
        }catch (ParseException e){
            e.printStackTrace();
        }
//        修改数据库中的该条数据
        boolean f = new UserDao().update(user);
        if(f){
            out.print("<script>alert('修改成功');document.location.href='/QueryAllServlet'</script>");
        }
        else{
            out.print("<script>alert('修改失败');document.location.href='/QueryAllServlet'</script>");
        }
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doPost(request, response);
    }
}
修改流程:在queryall.jsp中点击修改按钮跳转到UpdateQueryServlet去获取要修改的数据并存入域中，updata.jsp去获取存入域中的数据并显示在页面上，当修改完成之后点击确定按钮提交给UpdateSubmitServlet