使用java开发web项目时，可以在后端使用Servlet，前端使用JSP，下面就介绍一下这两者的配合使用。
Servlet的概念其实很简单，本质是一个遵从Servlet开发出来的java类。运行在 Web 服务器或应用服务器，它是作为来自 Web 浏览器或其他 HTTP 客户端的请求和 HTTP 服务器上的数据库或应用程序之间的中间层。
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JSP（全称Java Server Pages）是由 Sun Microsystems 公司倡导和许多公司参与共同创建的一种使软件开发者可以响应客户端请求，而动态生成 HTML、XML 或其他格式文档的Web网页的技术标准。JSP 技术是以 Java 语言作为脚本语言的，JSP 网页为整个服务器端的 Java 库单元提供了一个接口来服务于HTTP的应用程序。
特点：可以混杂Html和java代码！
其实JSP也是一种Servlet，JSP被编译后是Servlet类文件。而通常JSP更注重页面的显示，而Servlet更注重逻辑控制。
一个完整的网络请求：
下面是一个实际项目中的应用：
一个Servlet:
//GetAllLesson
package intergration.controller.lesson;
import intergration.Service.LessonService;
import intergration.entity.Lesson;
import org.jdom.JDOMException;
import org.xml.sax.SAXException;
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 javax.xml.parsers.ParserConfigurationException;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
@WebServlet("/lesson/getAllLesson") //访问Servlet的url
public class GetAllLesson extends HttpServlet {
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
//super.doGet(req, resp);
LessonService lessonService = new LessonService();
Map<String, Object> modelMap = new HashMap<String, Object>();
List<Lesson> lessonList = null;
try {
lessonList = lessonService.getAllLesson(); //从后台得到数据
} catch (ParserConfigurationException e) {
e.printStackTrace();
} catch (SAXException e) {
e.printStackTrace();
} catch (JDOMException e) {
e.printStackTrace();
}
modelMap.put("lesson", lessonList);
if(lessonList == null){
modelMap.put("success", false);
}else {
modelMap.put("success", true);
}
req.setAttribute("lesson_list",lessonList); //将数据传回前端
req.getRequestDispatcher("getAllLesson.jsp").forward(req, resp); //重定向
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
//super.doPost(req, resp);
doGet(req, resp);
}
}
对应的 getAllLesson.jsp
<%@ page import="java.util.List"%>
<%@ page import="intergration.entity.Lesson" %><%--
Created by IntelliJ IDEA.
User: Administrator
Date: 2019/11/27
Time: 17:17
To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>getAllLesson</title>
<link rel="stylesheet" type="text/css" href="<%=request.getContextPath()%>/css/public.css" />
</head>
<body>
<div id = "left_table">
<form action="getLessonById" method="post">
<input type="text" name="id" value="" placeholder="课程号" />
<button type ="submit">查询</button>
</form>
</div>
<div id = "table" >
<div class="add">
<form action="insertLesson" method="post">
<input type="text" name="id" value="" placeholder="ID" />
<input type="text" name="name" value="" placeholder="课程名" />
<input type="text" name="sex" value="" placeholder="教师" />
<input type="text" name="class" value="" placeholder="学时" />
<select name = "database">
<option value = "test1">test1</option>
<option value = "test2">test2</option>
</select>
<button type ="submit">新增</button>
</form>
</div>
<table cellpadding="0" cellspacing="0">
<thead>
<tr>
<th>ID</th>
<th>课程名</th>
<th>教师</th>
<th>学时</th>
</tr>
</thead>
<%
//获取数据
List<Lesson> lesson_list = (List<Lesson>)request.getAttribute("lesson_list");
%>
<%
for(Lesson lesson:lesson_list){
%>
<tbody>
<tr align="center">
<td> <%= lesson.getLessonId() %></td>
<td> <%= lesson.getLessonName() %></td>
<td> <%= lesson.getTeacherName() %></td>
<td> <%= lesson.getHours() %></td>
<td width="20%">
<span class="delete" ><a href="deleteLessonById?id=<%= lesson.getLessonId()%>">删除</a> </span>
<span class="edit" onclick="dis( <%= lesson.getLessonId() %>,'<%=lesson.getLessonName() %>',<%= lesson.getTeacherName() %>, <%= lesson.getHours() %>);">编辑</span>
</td>
</tr>
</tbody>
<%
}
%>
</table>
<div id="mask">
<div class="mask">
<div class="title">
编辑
<span onclick = "nodis()">
X
</span>
</div>
<div class="content">
<form action="updateLesson" method="post">
<input type="text" name="id" id = "update_id"value="" placeholder="ID" />
<input type="text" name="name" id = "update_name" value="" placeholder="课程名" />
<input type="text" name="sex" id = "update_sex"value="" placeholder="教师" />
<input type="text" name="class" id = "update_class"value="" placeholder="学时" />
<button type ="submit">更新</button>
</form>
</div>
</div>
</div>
</div>
</body>
<script>
function dis(Id,Name,Sex,Class) {
event.stopPropagation();
document.getElementById("mask").style.display = "block";
document.getElementById("update_id").setAttribute("placeholder",Id);
document.getElementById("update_name").setAttribute("placeholder",Name);
document.getElementById("update_sex").setAttribute("placeholder",Sex);
document.getElementById("update_class").setAttribute("placeholder",Class);
document.getElementById("update_id").setAttribute("value",Id);
document.getElementById("update_name").setAttribute("value",Name);
document.getElementById("update_sex").setAttribute("value",Sex);
document.getElementById("update_class").setAttribute("value",Class);
}
function nodis() {
event.stopPropagation();
document.getElementById("mask").style.display = "none";
}
</script>
</html>
原文：https://www.cnblogs.com/lyc1226/p/12142640.html