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...-优快云博客

本文介绍了一种服务器端提供最新视频资讯的方式，并演示了如何使用JSON和XML两种格式进行数据交互。具体包括服务器端代码实现及客户端如何解析这两种格式的数据。

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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; } }

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()); } } }