WebDemo01

indexhtml

DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title heretitle>
head>
<body style="text-align: center;background: url('https://gimg2.baidu.com/image_search/src=http%3A%2F%2Fpic.jj20.com%2Fup%2Fallimg%2F911%2F091316135137%2F160913135137-12.jpg&refer=http%3A%2F%2Fpic.jj20.com&app=2002&size=f9999,10000&q=a80&n=0&g=0n&fmt=auto?sec=1651287564&t=977119ee0b27f6373b448b0e0e986df7');">
    <h2>登录页面h2>
    <form action="login">
        账号：<input type="text" name="username"><br>
        密码：<input type="password" name="pw"><br>
        <input type="reset" value="重置">
        <input type="submit" value="登录"><br>
    form>
body>
html>

web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://xmlns.jcp.org/xml/ns/javaee" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd" version="3.1">
  <display-name>Demo01display-name>
  <welcome-file-list>
    <welcome-file>index.htmlwelcome-file>
    <welcome-file>index.htmwelcome-file>
    <welcome-file>index.jspwelcome-file>
    <welcome-file>default.htmlwelcome-file>
    <welcome-file>default.htmwelcome-file>
    <welcome-file>default.jspwelcome-file>
  welcome-file-list>
  
  
  <servlet>
      <servlet-name>tomservlet-name>
      <servlet-class>com.xl.www.LoginControllerservlet-class>
  servlet>
  
  
  <servlet-mapping>
      <servlet-name>tomservlet-name>
      <url-pattern>/loginurl-pattern>
  servlet-mapping>
  
  
web-app>

 LoginController.java

package com.xl.www;

import java.io.IOException;
import java.util.Date;

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

//http发送的请求可以被java里面的核心类 ：HttpServlet接受并处理
public class LoginController extends HttpServlet {
    //完成继承后 那么LonginController就变成了HttpServlet的子类  
    //那么就能接受并处理http请求了
    @Override
    protected void service(HttpServletRequest 请求, HttpServletResponse 响应) throws ServletException, IOException {
      //这个service方法就是用来接受并处理请求的，写具体逻辑业务的地方！
        //请求可能携带用户参数。响应一开始是空白的，我们自己来定义响应回去什么
        String username = 请求.getParameter("username");//通过此方法从请求中获取用户提交的数据
        响应.getWriter().print("Hello , Dear user: " + username + "现在的时间是："+ new Date());//向浏览器设置响应内容
        //前端是html，后端是java，属于两种不同的语言 需要连接起来
        // 通过web.xml来沟通连接
        
        
    }

    
    

}