Ich versuche, von meinem Telefon aus einen REST-Webdienst aufzurufen. Ich benutze folgenden Code, um dies abzuschließen. Ich habe nur eine Aktivität, die eine Schaltfläche und eine Textansicht hat. Immer wenn ich auf die Schaltfläche klicke, wird folgender Fehler angezeigtlogcat :

AndroidRuntime :: at android.os.Handler.dispatchMessage(Handler.java:92)

Was mache ich falsch? wie kann ich das lösen ??? Es folgen meine Kurse.

rest.java

public class Rest extends Activity {

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.start_rest);

    Button button = (Button) findViewById(R.id.btn);


    button.setOnClickListener(new View.OnClickListener(){
        @Override
        public void onClick(View v) {
            // TODO Auto-generated method stub
            String url = "http://192.168.1.145/tst.php";

            RestService re = new RestService();             
            JSONObject jb =  RestService.doGet(url);

            TextView tv = (TextView) findViewById(R.id.txtView);                
            tv.setText(jb.toString());
        }
    });

  }
}

RestService.java

public class RestService {

public static JSONObject doGet(String url) {
    JSONObject json = null;

    HttpClient httpclient = new DefaultHttpClient();
    // Prepare a request object
    HttpGet httpget = new HttpGet(url);
    // Accept JSON
    httpget.addHeader("accept", "application/json");
    // Execute the request
    HttpResponse response;

    try {
        response = httpclient.execute(httpget);
        // Get the response entity
       // Log.e("myApp", "Issue is here...!");
        HttpEntity entity = response.getEntity();
        // If response entity is not null
        if (entity != null) {
            // get entity contents and convert it to string
            InputStream instream = entity.getContent();
            String result= convertStreamToString(instream);
            // construct a JSON object with result
            json=new JSONObject(result);
            // Closing the input stream will trigger connection release
            instream.close();
        }
    } catch (ClientProtocolException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (JSONException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
    // Return the json
    return json;
}

private static String convertStreamToString(InputStream is) {

    BufferedReader br = null;
    StringBuilder sb = new StringBuilder();

    String line;
    try {

        br = new BufferedReader(new InputStreamReader(is));
        while ((line = br.readLine()) != null) {
            sb.append(line);
        }

    } catch (IOException e) {
        e.printStackTrace();
    } finally {
        if (br != null) {
            try {
                br.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }

    return sb.toString();
}
}