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<%@page language="java"import="java.util.*"pageEncoding="UTF-8"%>

也是可以的（最好不要）