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JSP 中Servlet的自己实现

作者：admin 时间：2021-08-28 19:04

JSP 中Servlet的自己实现

一步骤

1、继承HttpServlet
2、重写doGet()或者doPost()方法
3、在web.xml中注册Servlet

二 HttpServlet类继承图

三实例

1、创建MyFirstServletDemo web project.

2、编辑index.jsp

<%@ page language="java" import="java.util.*" contentType="text/html; charset=utf-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>
 
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
 <head>
 <base href="<%=basePath%>" rel="external nofollow" >
 
 <title>My JSP 'index.jsp' starting page</title>
  <meta http-equiv="pragma" content="no-cache">
  <meta http-equiv="cache-control" content="no-cache">
  <meta http-equiv="expires" content="0"> 
  <meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
  <meta http-equiv="description" content="This is my page">
  <!--
  <link rel="stylesheet" type="text/css" href="styles.css" rel="external nofollow" >
  -->
 </head>
 
 <body>
 <h1>第一个Servlet小例子</h1>
 <a href="servlet/HelloServlet" rel="external nofollow" >Get方式请求HelloServlet</a>
 <form action="servlet/HelloServlet" method="post">
    <input type="submit" value="Post方式请求HelloServlet">
 </form>
 </body>
</html>

3、编写HelloServlet

package servlet;
 
import java.io.IOException;
import java.io.PrintWriter;
 
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
 
//继承于HttpServlet
public class HelloServlet extends HttpServlet {
 
  @Override
  protected void doGet(HttpServletRequest request, HttpServletResponse response)
      throws ServletException, IOException {
    // TODO Auto-generated method stub
    System.out.println("处理get（）请求...");
    PrintWriter out = response.getWriter();
    response.setContentType("text/html; charset=utf-8");
    out.println("<strong>Hello Servlet!</strong><br>");
  }
 
  @Override
  protected void doPost(HttpServletRequest request, HttpServletResponse response)
      throws ServletException, IOException {
    System.out.println("处理post（）请求...");
    PrintWriter out = response.getWriter();
    response.setContentType("text/html; charset=utf-8");
    out.println("<strong>Hello Servlet!</strong><br>");
  }
 
}

4、编写web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5"
  xmlns="http://java.sun.com/xml/ns/javaee";
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance";
  xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd";>
 <display-name></display-name> 
 <welcome-file-list>
 <welcome-file>index.jsp</welcome-file>
 </welcome-file-list>
 <servlet>
  <servlet-name>HelloServlet</servlet-name>
  <servlet-class>servlet.HelloServlet</servlet-class>
 </servlet>
 <servlet-mapping>
   <servlet-name>HelloServlet</servlet-name>
   <url-pattern>/servlet/HelloServlet</url-pattern>
 </servlet-mapping>
</web-app>

四运行结果