Android之从网络中获取数据并返回客户端的两种方式:XML格式返回与Json格式返回

1.服务器端代码样例：

public class VideoListAction extends Action 
{
	private VideoService service = new VideoServiceBean();
	public ActionForward execute(ActionMapping mapping, ActionForm form,
			HttpServletRequest request, HttpServletResponse response)
			throws Exception 
	{
		//得到最新的视频资讯
		List<Video> videos = service.getLastVideos();
		VideoForm formbean = (VideoForm)form;
		if("json".equals(formbean.getFormat()))
		{
			//构建json字符串
			StringBuilder json = new StringBuilder();
			json.append('[');
			for(Video video : videos)
			{ // 需要构造的形式是{id:76,title:"xxxx",timelength:80}
				json.append('{');
				json.append("id:").append(video.getId()).append(',');
				json.append("title:\"").append(video.getTitle()).append("\",");
				json.append("timelength:").append(video.getTime());
				json.append('}').append(',');
			}
			json.deleteCharAt(json.length()-1);
			json.append(']');
			//把json字符串放置于request
			request.setAttribute("json", json.toString());
			return mapping.findForward("jsonvideo");
		}
		else
		{			
			request.setAttribute("videos", videos);
			return mapping.findForward("video");
		}
	}
}

public class VideoServiceBean implements VideoService 
{
	public List<Video> getLastVideos() throws Exception
	{
		//理论上应该查询数据库
		List<Video> videos = new ArrayList<Video>();
		videos.add(new Video(78, "喜羊羊与灰太狼全集", 90));
		videos.add(new Video(78, "实拍舰载直升东海救援演习", 20));
		videos.add(new Video(78, "喀麦隆VS荷兰", 30));
		return videos;
	}
}

public class VideoListAction extends Action 
{
	private VideoService service = new VideoServiceBean();
	public ActionForward execute(ActionMapping mapping, ActionForm form,
			HttpServletRequest request, HttpServletResponse response)
			throws Exception 
	{
		//得到最新的视频资讯
		List<Video> videos = service.getLastVideos();
		VideoForm formbean = (VideoForm)form;
		if("json".equals(formbean.getFormat()))
		{
			//构建json字符串
			StringBuilder json = new StringBuilder();
			json.append('[');
			for(Video video : videos)
			{ // 需要构造的形式是{id:76,title:"xxxx",timelength:80}
				json.append('{');
				json.append("id:").append(video.getId()).append(',');
				json.append("title:\"").append(video.getTitle()).append("\",");
				json.append("timelength:").append(video.getTime());
				json.append('}').append(',');
			}
			json.deleteCharAt(json.length()-1);
			json.append(']');
			//把json字符串放置于request
			request.setAttribute("json", json.toString());
			return mapping.findForward("jsonvideo");
		}
		else
		{			
			request.setAttribute("videos", videos);
			return mapping.findForward("video");
		}
	}
}

2.客户端：使用XML方式与JSON方式返回数据

public class VideoService 
{
	/**
	 * 以XML方式返回获取最新的资讯
	 * @return
	 * @throws Exception
	 */
	public static List<Video> getLastVideos() throws Exception
	{
		//确定请求服务器的地址
		//注意在Android模拟器中访问本机服务器时不可以使用localhost与127字段
		//因为模拟器本身是使用localhost绑定
		String path = "http://192.168.1.100:8080/videoweb/video/list.do";
		//建立一个URL对象
		URL url = new URL(path);
		//得到打开的链接对象
		HttpURLConnection conn = (HttpURLConnection)url.openConnection();
		//设置请求超时与请求方式
		conn.setReadTimeout(5*1000);
		conn.setRequestMethod("GET");
		//从链接中获取一个输入流对象
		InputStream inStream = conn.getInputStream();
		//对输入流进行解析
		return parseXML(inStream);
	}
	
	/**
	 * 解析服务器返回的协议，得到资讯
	 * @param inStream
	 * @return
	 * @throws Exception
	 */
	private static List<Video> parseXML(InputStream inStream) throws Exception
	{
		List<Video> videos = null;
		Video video = null;
		//使用XmlPullParser
		XmlPullParser parser = Xml.newPullParser();
		parser.setInput(inStream, "UTF-8");
		int eventType = parser.getEventType();//产生第一个事件
		//只要不是文档结束事件
		while(eventType!=XmlPullParser.END_DOCUMENT)
		{
			switch (eventType) 
			{
				case XmlPullParser.START_DOCUMENT:
					videos = new ArrayList<Video>();
					break;		
					
				case XmlPullParser.START_TAG:
					//获取解析器当前指向的元素的名称
					String name = parser.getName();
					if("video".equals(name))
					{
						video = new Video();
						//把id属性写入
						video.setId(new Integer(parser.getAttributeValue(0)));
					}
					if(video!=null)
					{
						if("title".equals(name))
						{
							//获取解析器当前指向元素的下一个文本节点的值
							video.setTitle(parser.nextText());
						}
						if("timelength".equals(name))
						{
							//获取解析器当前指向元素的下一个文本节点的值
							video.setTime(new Integer(parser.nextText()));
						}
					}
					break;
					
				case XmlPullParser.END_TAG:
					if("video".equals(parser.getName()))
					{
						videos.add(video);
						video = null;
					}
					break;
			}
			eventType = parser.next();
		}
		return videos;
	}
	
	/**
	 * 以Json方式返回获取最新的资讯，不需要手动解析，JSON自己会进行解析
	 * @return
	 * @throws Exception
	 */
	public static List<Video> getJSONLastVideos() throws Exception
	{
		//
		List<Video> videos = new ArrayList<Video>();
		//
		String path = "http://192.168.1.100:8080/videoweb/video/list.do?format=json";
		//建立一个URL对象
		URL url = new URL(path);
		//得到打开的链接对象
		HttpURLConnection conn = (HttpURLConnection)url.openConnection();
		//设置请求超时与请求方式
		conn.setReadTimeout(5*1000);
		conn.setRequestMethod("GET");
		//从链接中获取一个输入流对象
		InputStream inStream = conn.getInputStream();
		//调用数据流处理方法
		byte[] data = StreamTool.readInputStream(inStream);
		String json = new String(data);
		//构建JSON数组对象
		JSONArray array = new JSONArray(json);
		//从JSON数组对象读取数据
		for(int i=0 ; i < array.length() ; i++)
		{
			//获取各个属性的值
			JSONObject item = array.getJSONObject(i);
			int id = item.getInt("id");
			String title = item.getString("title");
			int timelength = item.getInt("timelength");
			//构造的对象加入集合当中
			videos.add(new Video(id, title, timelength));
		}
		return videos;
	}
}

public class StreamTool 
{
	/**
	 * 从输入流中获取数据
	 * @param inStream 输入流
	 * @return
	 * @throws Exception
	 */
	public static byte[] readInputStream(InputStream inStream) throws Exception{
		ByteArrayOutputStream outStream = new ByteArrayOutputStream();
		byte[] buffer = new byte[1024];
		int len = 0;
		while( (len=inStream.read(buffer)) != -1 ){
			outStream.write(buffer, 0, len);
		}
		inStream.close();
		return outStream.toByteArray();
	}
}

public class MainActivity extends Activity 
{
    private ListView listView;
    @Override
    public void onCreate(Bundle savedInstanceState) 
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        //获取到ListView对象
        listView = (ListView)this.findViewById(R.id.listView);
        try 
        {
        	//通过
        	List<Video> videos = VideoService.getLastVideos();
        	//通过Json方式获取视频内容
			//List<Video> videos2 = VideoService.getJSONLastVideos();
			//
        	List<HashMap<String, Object>> data = new ArrayList<HashMap<String,Object>>();
			//迭代传入
			for(Video video : videos)
			{
				//把video中的数据绑定到item中
				HashMap<String, Object> item = new HashMap<String, Object>();
				item.put("id", video.getId());
				item.put("title", video.getTitle());
				item.put("timelength", "时长:"+ video.getTime());
				data.add(item);
			}
			//使用SimpleAdapter处理ListView显示数据
			SimpleAdapter adapter = new SimpleAdapter(this, data, R.layout.item, 
					new String[]{"title", "timelength"}, new int[]{R.id.title, R.id.timelength});
			//
			listView.setAdapter(adapter);
		} 
        catch (Exception e) 
        {
			Toast.makeText(MainActivity.this, "获取最新视频资讯失败", 1).show();
			Log.e("MainActivity", e.toString());
		} 
    }
}

评论

1 楼 荒村听雨 2012-04-01  

很有用，学习一下。
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