Android开发18——获取网络资源之json数据
一、项目背景
在Android开发中有一项非常广泛的应用：Android项目获取另一个web项目的资源或者返回的数据。
本文获取web项目返回的JSON数据。Android应用解析JSON比XML性能要好，但有许多项目仍然采用的是XML。
二、实例代码
Web项目
- /**
- * 新闻业务类
- *
- * @author 徐越
- *
- */
- public class VideoNewsServiceImpl implements VideoNewsService
- {
- public List<VideoNews> readNews()
- {
- List<VideoNews> lst = new ArrayList<VideoNews>();
- lst.add(new VideoNews(1, "喜洋洋", 20));
- lst.add(new VideoNews(2, "变形金刚", 10));
- lst.add(new VideoNews(3, "功夫熊猫", 20));
- return lst;
- }
- }
- /**
- * 新闻Servlet
- *
- * @author 徐越
- *
- */
- public class ListServlet extends HttpServlet
- {
- private static final long serialVersionUID = 1L;
- private VideoNewsService vs = new VideoNewsServiceImpl();
- protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException
- {
- doPost(request, response);
- }
- protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException
- {
- List<VideoNews> news = vs.readNews();
- JSONArray jsonarr = JSONArray.fromObject(news);
- response.setCharacterEncoding("UTF-8");
- response.setContentType("text/plain;charset=UTF-8");
- response.setHeader("Pragma", "No-cache");
- response.setHeader("Cache-Control", "no-cache");
- response.setDateHeader("Expires", 0);
- response.getWriter().print(jsonarr);
- }
- }
Android项目
- public class VideoNewsServiceImpl implements VideoNewsService
- {
- /**
- * 获取最新视频资讯，从JSON文件中，解析效率高
- *
- * @return
- * @throws Exception
- */
- public List<VideoNews> getNewsFromJson() throws Exception
- {
- List<VideoNews> lst = new ArrayList<VideoNews>();
- String path = "http://xxx.xxx.xxx.xxx:8080/web/ListServlet";
- URL url = new URL(path);
- HttpURLConnection conn = (HttpURLConnection) url.openConnection();
- conn.setReadTimeout(5000);
- conn.setRequestMethod("GET");
- if (200 == conn.getResponseCode())
- {
- InputStream instream = conn.getInputStream();
- lst = parseJSON(instream);
- }
- return lst;
- }
- /**
- * 解析JSON
- */
- private List<VideoNews> parseJSON(InputStream instream) throws Exception
- {
- List<VideoNews> lst = new ArrayList<VideoNews>();
- byte[] data = IOUtils.read(instream);
- String jsonStr = new String(data);
- JSONArray array = new JSONArray(jsonStr);
- for (int i = 0; i < array.length(); i++)
- {
- JSONObject jsonObj = (JSONObject) array.getJSONObject(i);
- VideoNews v = new VideoNews(jsonObj.getInt("id"),
- jsonObj.getString("title"), jsonObj.getInt("timeLength"));
- lst.add(v);
- }
- return lst;
- }
- }
- /**
- * IO操作工具类
- *
- * @author 徐越
- *
- */
- public class IOUtils
- {
- /**
- * 读取输入流为byte[]数组
- */
- public static byte[] read(InputStream instream) throws IOException
- {
- ByteArrayOutputStream bos = new ByteArrayOutputStream();
- byte[] buffer = new byte[1024];
- int len = 0;
- while ((len = instream.read(buffer)) != -1)
- {
- bos.write(buffer, 0, len);
- }
- return bos.toByteArray();
- }
- }
需要指出的是
在web项目中我采用的是net.sf.json下的类对JSON进行解析，而Android项目中默认自带的JSON包是org.json。API有所不同，只要熟悉一下即可。
本文转自IT徐胖子的专栏博客51CTO博客，原文链接http://blog.51cto.com/woshixy/1088074如需转载请自行联系原作者
woshixuye111
