android.os.NetworkOnMainThreadException 异常处理

在android 4.0上运行时报android.os.NetworkOnMainThreadException异常，在4.0中，访问网络不能在主程序中进行，有三个方法可以解决，一个是在主程序中增加：

//安卓2.3以后访问网络增加内容
		StrictMode.setThreadPolicy(new StrictMode.ThreadPolicy.Builder()
					.detectDiskReads()
					.detectDiskWrites()
					.detectNetwork()
					.penaltyLog()
					.build()); 
		StrictMode.setVmPolicy(new StrictMode.VmPolicy.Builder()
					.detectLeakedSqlLiteObjects()
					.detectLeakedClosableObjects()
					.penaltyLog()
					.penaltyDeath()
					.build());

第二种采用异步方式：

private class GeocodeingOnclickListener implements OnClickListener{
		@Override
		public void onClick(View v) {
			new GeocodeingTask().execute();
		}
	}
	private class GeocodeingTask extends AsyncTask<Integer, Integer, Integer>{
		@Override
		protected Integer doInBackground(Integer... params) {
			String url="http://maps.googleapis.com/maps/api/geocode/json?" +
					"latlng=35.95405270,117.30649970&sensor=false";
			//创建一个Httpclient对象
			HttpClient httpClient=new DefaultHttpClient();
			String responseData="";
			try {
				//向指定的Http地址发送请求
				HttpResponse httpResponse=httpClient.execute(new HttpPost(url));
				//取得服务器返回的响应
				HttpEntity httpEntity=httpResponse.getEntity();
				BufferedReader bufferedReader=new BufferedReader(new InputStreamReader(httpEntity.getContent()));
				String line="";
				while((line=bufferedReader.readLine())!=null){
					responseData=responseData+line;
				}
			} catch (ClientProtocolException e) {
				e.printStackTrace();
			} catch (IOException e) {
				e.printStackTrace();
			}
			Gson gson=new Gson();
			TestResult result=gson.fromJson(responseData, TestResult.class);
			System.out.println(result.toString());
			return null;
		}
	}

第三种采用线程的方式（与第二种类似 都是异步的方式）

        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        // 启动线程执行下载任务
        new Thread(downloadRun).start();
    }
    
    /**
     * 下载线程
     */
    Runnable downloadRun = new Runnable(){

		@Override
		public void run() {
			// TODO Auto-generated method stub
			updateListView();
		}
    };