前台
<%--Created by IntelliJ IDEA.User: xxDate: 2023/9/4Time: 10:00To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head><title>Title</title><script src="js/jquery-3.7.0.js"></script><script>// 1.原始方式/*function like(){window.location.href = "likeServlet"}*/// 2.原生JS实现异步function like(){//获取XmlHttpRequest对象var xhr = new XMLHttpRequest();//设置请求xhr.open("get","likeServlet");//发送请求xhr.send();xhr.onreadystatechange = function (){//获取状态码if ( xhr.readyState== 4){var msg = xhr.responseText;document.getElementById("num").innerText = msg;}}}// 3.第一次封装/*$(function () {//点击事件$("#btn").click(function () {$.ajax({url:"likeServlet",data:null,type:"get",async:true,dataType:"text",success:function (msg) {$("#num").text(msg);}});});});*/// 4.第二次封装/*$(function (){$("#btn").click(function (){$.get("likeServlet",null,function (date) {$("#num").text(date)},"text");});})*/</script>
</head>
<body>
<video src="" controls></video>
<input type="button" id="btn" onclick="like()" value="点赞"></input>当前点赞量为：
<span style="color: red" id = "num">${count}
</span>
</body>
</html>
servlet
import javax.servlet.ServletContext;
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;@WebServlet("/likeServlet")
public class LikeServlet extends HttpServlet {@Overrideprotected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {//将获取的点赞了存储到ServletContextServletContext servletContext = getServletContext();//获取当前点赞量Integer count =(Integer) servletContext.getAttribute("count");//如果是第一个点赞if (count == null){count = 1;} else {count++;}servletContext.setAttribute("count",count);/*原生js*//*resp.sendRedirect("video.jsp");*//*ajax*/PrintWriter writer = resp.getWriter();writer.print(count);writer.close();}
}
