手工编写第一个Servlet

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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 %> " >

   

    < 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" >

        

  head >

 

  < body >

    < h1 > 第一个 Servlet 小例子 h1 >

    < a href = "servlet/HelloServlet" > 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( "Hello Servlet!
" );

        }

 

         @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( "Hello Servlet!
" );

        }

 

}

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

 

 

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