获取服务器上的XML资源，并在客户端上解析出来

         从服务器上获取XML资源，并在客户端上解析下来，

实现的步骤如下：

1.pull  解析网络上XML文件的内容
   1.新建一个URL链接对象、并打开链接（HttpURLConnection）
   2.设置一些参数，比如链接超时，请求方式（GET、POST）等
   3.得到xml的输入流getInputStream（）；
   4.用pull解析XML文件
      1.实例化一个newPullParser对象
      2.得到解析的类型getEventType
      3.从START_DOCUMENT、START_TAG、END_TAG、END_DOCUMENT对XML进行解析，返回解析的内容
   5.解析过程中需要用到Bean的一些get、set、以及构造函数的一些方法   

服务器端实现的代码下载地址：源码下载

客户端实现的代码下载地址：源码下载

实现的效果如下：

这时候会出现以下异常：

Error parsing document. (position:line -1, column -1) caused by: org.apache.harmony.xml.ExpatParser$ParseException: At line 2, column 0: XML or text declaration not at start of entity; nested exception is:

产生异常的原因是因为：JSP代码中的<%@ page language="java" contentType="text/xml; charset=UTF-8" pageEncoding="UTF-8"%><%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>被放在最前面了，这样会导致XML前面出现空行，所以解析的时候会报-1行和-1列

在XML解析文档的时候默认的是从<?xml version="1.0" encoding="UTF-8"?>开始的

解决方法如下：

<?xml version="1.0" encoding="UTF-8"?><%@ page language="java" contentType="text/xml; charset=UTF-8" pageEncoding="UTF-8"%><%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>
<newslist>
	<c:forEach items="${newes}" var="news">
		<news id="${news.id}">
			<title>${news.title}</title>
			<timelength>${news.timelength}</timelength>
		</news>
	</c:forEach>
</newslist>

客户端实现的代码：

bean的实现News的方法和解析的代码如下：

public class NewsService {

	public static List<News> getLastNews() throws Exception {

		String path = "http://10.8.2.33/WebXMLDemo/ServletForXML";
		HttpURLConnection connection = (HttpURLConnection) new URL(path)
				.openConnection();
		connection.setConnectTimeout(5000);
		connection.setRequestMethod("GET");
		if (connection.getResponseCode() == 200) {
			InputStream xml = connection.getInputStream();
			return parseXML(xml);
		}

		return null;
	}

	private static List<News> parseXML(InputStream xml) throws Exception {
		List<News> newes = null;
		News news = null;
//		XmlPullParser pullParser = Xml.newPullParser();
		XmlPullParser pullParser=XmlPullParserFactory.newInstance().newPullParser();
		pullParser.setInput(xml, "UTF-8");
		int event = pullParser.getEventType();
		while (event != XmlPullParser.END_DOCUMENT) {

			switch (event) {
			case XmlPullParser.START_DOCUMENT:
				newes = new ArrayList<News>();
				break;
			case XmlPullParser.START_TAG:
				if ("news".equals(pullParser.getName())) {
					int id = new Integer(pullParser.getAttributeValue(0));
					news = new News();
					news.setId(id);
				}
				if ("title".equals(pullParser.getName())) {
					news.setTitle(pullParser.nextText());
				}
				if ("timelength".equals(pullParser.getName())) {
					news.setTimelength(new Integer(pullParser.nextText()));
				}

				break;

			case XmlPullParser.END_TAG:
				if ("news".equals(pullParser.getName())) {
					newes.add(news);
					news = null;
				}

				break;

			}
		event=pullParser.next();
		}

		return newes;
	}

}

实现Activity的方法如下：

public class GetXMLDemoActivity extends Activity {
	/** Called when the activity is first created. */
	@Override
	public void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.list);

		ListView listView = (ListView) findViewById(R.id.list);
		String length = getResources().getString(R.string.length);

		try {

			List<News> newlist = NewsService.getLastNews();
			List<HashMap<String, Object>> data = new ArrayList<HashMap<String, Object>>();
			for (News news : newlist) {
				HashMap<String, Object> item = new HashMap<String, Object>();
				item.put("id", news.getId());
				item.put("title", news.getTitle());
				item.put("timelength", length + news.getTimelength());
				data.add(item);
			}
			SimpleAdapter adapter = new SimpleAdapter(this, data,
					R.layout.list_item, new String[] { "title", "timelength" },
					new int[] { R.id.title, R.id.timelength });
			listView.setAdapter(adapter);

		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}

	}

服务器端实现的代码如下：

实现请求的Servlet方法

public class ServletForXML extends HttpServlet {
	private static final long serialVersionUID = 1L;
	private XMLService newsService = new XMLServiceBean();

	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		doPost(request, response);
	}

	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		
		List<News> newes = newsService.getLastNews();
		request.setAttribute("newes", newes);
		request.getRequestDispatcher("/WEB-INF/page/news.jsp").forward(request, response);
	
	}

}

实现bean的业务方法和添加测试数据的方法如下

public class XMLServiceBean implements XMLService {

	@Override
	public List<News> getLastNews() {
		List<News> newes = new ArrayList<News>();
		newes.add(new News(10, "wangjie", 20));
		newes.add(new News(45, "test", 10));
		newes.add(new News(89, "good", 50));
		return newes;
	}

}