25_Android_网络通信之资讯客户端（上）

一般的来说，中小型的应用Android与服务器的通讯方式是直接通过Url路径请求servlet，然后servlet返回xml数据（或者Json数据）这些xml文件里面又包括一些路径（比如图片的url路径，显示图片就通过这个路径下载）。而且有服务器跳转的技术

Web端的开发：

public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {List<News> videos = new NewsService().getLatestNews();request.setAttribute("videos", videos);request.getRequestDispatcher("index.jsp").forward(request, response);}public void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {List<News> videos = new NewsService().getLatestNews();request.setAttribute("videos", videos);request.getRequestDispatcher("index.jsp").forward(request, response);}}

注意两个地方：

1. 最好doPost与doGet都写，要不然加入用户以Post方式发送请求的时候，只写doGet没有任何回应，结果不知道错在哪里

2. 注意路径的书写，加入是在WEB-INF里面新建一个page文件夹，里面有一个news.jsp文件，那么路径就是WEB-INF/page/news.jsp

NewsService：

public class NewsService {public List<News>  getLatestNews(){List<News> news=new ArrayList<News>();news.add(new News(1,"喜羊羊与灰太狼",20));news.add(new News(2,"喜羊羊与灰太狼",30));news.add(new News(3,"喜羊羊与灰太狼",30));news.add(new News(4,"喜羊羊与灰太狼",60));news.add(new News(5,"喜羊羊与灰太狼",45));news.add(new News(6,"喜羊羊与灰太狼",32));return news;}}

News：

public class News {private Integer id;private String   name;private Integer  timeLength;public News(){}public News(Integer id, String name, Integer timeLength) {this.id = id;this.name = name;this.timeLength = timeLength;}public Integer getId() {return id;}public void setId(Integer id) {this.id = id;}public String getName() {return name;}public void setName(String name) {this.name = name;}public Integer getTimeLength() {return timeLength;}public void setTimeLength(Integer timeLength) {this.timeLength = timeLength;}}

index.jsp：使用的是JSTL

<?xml version="1.0" encoding="UTF-8"?><%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%><%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%><Videonews><c:forEach items="${videos}" var="video"><id>${video.id }</id><name>${video.name}</name><timeLength>${video.timeLength}</timeLength></c:forEach> </Videonews>

注意：事实上这个index.jsp完全可以这样写：

<?xmlversion="1.0"encoding="UTF-8"?>

<%@ taglib uri="http://java.sun.com/jsp/jstl/core"prefix="c"%>

<Videonews>

<c:forEachitems="${videos}"var="video">

   <id>${video.id }</id>

   <name>${video.name}</name>

   <timeLength>${video.timeLength}</timeLength>

</c:forEach></Videonews>

不要<%@pagelanguage="java"import="java.util.*"pageEncoding="UTF-8"%>

也是可以的（最好不要）