servlet helloworld(一)

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servlet概述

servlet是服务器端的java应用程序。是客户端请求与服务器响应的中间桥梁。

servlet生命周期

初始化，调用init();
响应客户端请求，调用service();
销毁，调用destroy();

HelloWorld

页面index.jsp.用于发送请求的客户端页面

<%@ page language="java" contentType="text/html; charset=UTF-8"    pageEncoding="UTF-8"%><!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"><html><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><title>Insert title here</title></head><body><form action="ServletDemo" method="post"><table><tr><td>用户名：</td><td><input type="text" name="username"></input></td></tr><tr><td>密 码:</td><td><input type="password" name="password"></input></td></tr><tr><td><input type="submit" value="提交"></input></td></tr></table></form></body></html>

2.页面result.jsp.用于显示响应结果的客户端页面

<%@ page language="java" contentType="text/html; charset=UTF-8"    pageEncoding="UTF-8"%><!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"><html><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><title>Insert title here</title></head><body>您的用户名：<%=request.getAttribute("username")%><br>您的密码：<%=request.getAttribute("password")%></body></html>

3. HelloWorld.java.仅仅用于Console显示

/** * Cappuccino's Class File */package com.aaron.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;/** * @author Cappuccino * 2012-6-10下午12:53:57 */public class HelloWorld extends HttpServlet {/** *  */private static final long serialVersionUID = 2114610983564440107L;@Overrideprotected void doGet(HttpServletRequest req, HttpServletResponse resp)throws ServletException, IOException {doPost(req, resp);}@Overrideprotected void doPost(HttpServletRequest req, HttpServletResponse resp)throws ServletException, IOException {System.out.println("servlet doPost!");PrintWriter out = resp.getWriter();out.print("Servlet HelloWorld");}}

4. ServletDemo.java。用于响应index.jsp页面的请求，将返回的结果返回到result.jsp页面。

/** * Cappuccino's Class File */package com.aaron.servlet;import java.io.IOException;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;/** * @author Cappuccino * 2012-6-10下午05:02:01 */public class ServletDemo extends HttpServlet {/** *  */private static final long serialVersionUID = -4392447839946325219L;@Overrideprotected void doGet(HttpServletRequest req, HttpServletResponse resp)throws ServletException, IOException {doPost(req, resp);}@Overrideprotected void doPost(HttpServletRequest req, HttpServletResponse resp)throws ServletException, IOException {String username = req.getParameter("username");String password = req.getParameter("password");//保存参数用于页面显示req.setAttribute("username", username);req.setAttribute("password", password);//页面跳转req.getRequestDispatcher("result.jsp").forward(req,resp); //传值跳转//resp.sendRedirect("result.jsp");//不传值跳转//控制台打印System.out.println("username:"+username);System.out.println("password:"+password);}}

5 . web.xml.配置servlet。

<?xml version="1.0" encoding="UTF-8"?><web-app id="WebApp_ID" version="2.4" xmlns="http://java.sun.com/xml/ns/j2ee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd"><display-name>Servlet-leaning</display-name><welcome-file-list><welcome-file>index.jsp</welcome-file></welcome-file-list><servlet>  <servlet-name>HelloWorld</servlet-name>  <servlet-class>com.aaron.servlet.HelloWorld</servlet-class></servlet><servlet-mapping>  <servlet-name>HelloWorld</servlet-name>  <url-pattern>/helloworldPage</url-pattern></servlet-mapping><servlet>  <servlet-name>ServletDemo</servlet-name>  <servlet-class>com.aaron.servlet.ServletDemo</servlet-class></servlet><servlet-mapping>  <servlet-name>ServletDemo</servlet-name>  <url-pattern>/ServletDemo</url-pattern></servlet-mapping></web-app>

参考：

1.http://baike.baidu.com/view/25169.htm

2.http://java.sun.com/j2ee/tutorial/1_3-fcs/doc/Servlets.html