Android 解析JSON对象及实例说明

JSON是一种轻量级的对象，数据体积小，方便传输，易于解析!

首先新建一个类工具类JsonUtil，用于获取请求返回的数据


代码如下:

public class JsonUtil {
 private static final String TAG = "JSONUTIL";
 public static JSONObject getJSON(String url) throws Exception {
  return new JSONObject(getRequest(url));
 }
 protected static String getRequest(String url) {
  return getRequest(url, new DefaultHttpClient(new BasicHttpParams()));
 }
 protected static String getRequest(String url, DefaultHttpClient client) {
  String result = null;
  int statusCode = 0;
  HttpGet httpGet = new HttpGet(url);
  try {
   HttpResponse httpResponse = client.execute(httpGet);
   statusCode = httpResponse.getStatusLine().getStatusCode();// statusCode为200时表示请求数据成功
   result = parseInputStream(httpResponse.getEntity());
  } catch (ClientProtocolException e) {
   e.printStackTrace();
  } catch (IOException e) {
   e.printStackTrace();
  } finally {
   httpGet.abort();
  }
  return result;
 }
 private static String parseInputStream(HttpEntity entity) {
  StringBuilder sb = null;
  try {
   sb = new StringBuilder("");
   InputStream inputStream = entity.getContent();
   int length = 0;
   byte[] buffer = new byte[1024];
   while ((length = inputStream.read(buffer)) > -1) {
    sb.append(new String(buffer, 0, length));
   }
   return sb.toString();
  } catch (IllegalStateException e) {
   e.printStackTrace();
  } catch (IOException e) {
   e.printStackTrace();
  }
  return sb.toString();
 }
}

获取数据并解析数据:
注:模拟器访问自己电脑上的网站不能用localhost:8080或者127.0.0.1:8080，因为模拟器默认将模拟器本身设定为localhost，所以如果设置为这样的方式就将访问模拟器本身。我们需要将主机名修改为10.0.2.2，此主机名是模拟器设定的特定的访问自己电脑的主机名，它记录了你的电脑的名称。
另外：获取数据需要将下面的方法封装到一个新线程中，不能放在程序主线程当中！


代码如下:

/* http://10.0.2.2:8080/index.jsp
  * { students:[{name:'Livingstone',age:25},{name:'LS',age:26}], class:'09GIS' }
  */
 private void Livingstone() {
  try {
   String URL = "http://10.0.2.2:8080/index.jsp";
   // 获取后台返回的JSON对象 --> { students:[{name:'Livingstone',age:25},{name:'LS',age:26}],class:'09GIS班' }
   JSONObject jObj = JsonUtil.getJSON(URL);
   // 获取学生数组 --> students:[{name:'Livingstone',age:25},{name:'LS',age:26}]
   JSONArray jArr = jObj.getJSONArray("students");
   // 获取班级 --> class:'09GIS班'
   String classname = jObj.getString("class");
   // 根据索引获取第一个学生的JSON对象 --> {name:'Livingstone',age:25}
   JSONObject j1 = jArr.getJSONObject(0);

String studentInfo = jArr.length() + "个学生" + j1.getString("name")
     + j1.getInt("age");
  } catch (Exception e) {
   e.printStackTrace();
  }
 }