didRangeBeaconsInRegion和REST REST服务

Question

我试图在此方法中调用rest服务，并返回以下错误：

public void didRangeBeaconsInRegion(Collection<Beacon> beacons, Region region) {
  for (Beacon beacon: beacons) {
    logToDisplay( "ok, detectou beacons" );

    RequestParams params = new RequestParams();
    params.put("beaconId", "gass76382hshsfk");
    AsyncHttpClient client = new AsyncHttpClient();
    client.get("http://192.168.1.130:8080/BeaconServer/palestra/listarPalestras", params, new AsyncHttpResponseHandler() {
      // When the response returned by REST has Http response code '200'
      @Override
      public void onSuccess(int arg0, Header[] arg1, byte[] response) {
        try {
          String respString = new String(response, "UTF-8");
          JSONObject obj = new JSONObject(respString);
          JSONArray jsonArray = obj.getJSONArray("palestra");

          for (int i = 0; i < jsonArray.length(); i++) {
            JSONObject jsonObject = jsonArray.getJSONObject(i);
            String nomePalestrante = jsonObject.getString("nomePalestrante");
            String assuntoPalestra = jsonObject.getString("assuntoPalestra");
            String beaconId = jsonObject.getString("beaconId");

            logToDisplay(nomePalestrante + "\r\n" + assuntoPalestra + "\r\n" + beaconId + "\r\n");

            //string+"\r\n";  
          }
        } catch (JSONException e) {
          // TODO Auto-generated catch block
          logToDisplay("JSONException e");
          Toast.makeText(getApplicationContext(),
            "Error Occured [Server's JSON response might be invalid]!",
            Toast.LENGTH_LONG).show();
          e.printStackTrace();
        } catch (UnsupportedEncodingException e) {
          // erro ao converter o array de bytes json para String
          e.printStackTrace();
        }
      }

      // When the response returned by REST has Http response code other than '200'
      @Override
      public void onFailure(int statusCode, Header[] headers, byte[] errorResponse, Throwable e) {
        // Hide Progress Dialog
        // When Http response code is '404'
        if (statusCode == 404) {
          logToDisplay("404 " + errorResponse.toString());
          Toast.makeText(getApplicationContext(),
            "Requested resource not found",
            Toast.LENGTH_LONG).show();
        }
        // When Http response code is '500'
        else if (statusCode == 500) {
          logToDisplay("500 " + errorResponse.toString());
          Toast.makeText(getApplicationContext(),
              "Something went wrong at server end",
              Toast.LENGTH_LONG).show();
        }
        // When Http response code other than 404, 500
        else {
          logToDisplay("outros " + errorResponse.toString());
          Toast.makeText(getApplicationContext(),
              "Unexpected Error occcured! [Most common Error: Device might not be connected to Internet or remote server is not up and running]",
              Toast.LENGTH_LONG).show();
        }
      }
    });
  }
}

下面显示的错误是，不知道还需要做什么

03-29 21:04:16.034: d/蓝牙适配器(10437)：stopLeScan() 03-29 21:04:16.043: d/蓝牙适配器(10437)：startLeScan()：null 03-29 21:04:16.051: d/蓝牙适配器(10437)：onClientRegistered() - status=0 clientIf=5 03-29 21:04:16.322: W/dalvikvm(10437)：threadid=15:线程退出与未明异常(group=0x416f9d40) 03-29 21:04:17.185: d/蓝牙适配器(10437)：stopLeScan() 03-29 21:04:17.195: d/蓝牙适配器(10437)：startLeScan()：null 03-29 21:04:17.202: d/蓝牙适配器(10437)：onClientRegistered() - status=0 clientIf=5 03-29 21:04:18.332: d/蓝牙适配器(10437)：stopLeScan() 03-29 21:04:18.340: d/蓝牙适配器(10437)：startLeScan()：null 03-29 21:04:18.347: d/蓝牙适配器(10437)：onClientRegistered() - status=0 clientIf=5 03-29 21:04:19.467: d/蓝牙适配器(10437)：stopLeScan() 03-29 21:04:19.476: d/蓝牙适配器(10437)：startLeScan()：null 03-29 21:04:19.485: d/蓝牙适配器(10437)：onClientRegistered() - status=0 clientIf=5 03-29 21:04:20.618: d/蓝牙适配器(10437)：stopLeScan() 03-29 21:04:20.627: d/蓝牙适配器(10437)：startLeScan()：null 03-29 21:04:20.633: d/蓝牙适配器(10437)：onClientRegistered() - status=0 clientIf=5 03-29 21:04:21.476: E/AndroidRuntime(10437)：致命异常: IntentServiceBeaconIntentProcessor 03-29 21:04:21.476: E/AndroidRuntime( 10437 )：进程: org.altbeacon.beaconreference，PID: 10437 03-29 21:04:21.476: E/AndroidRuntime(10437)：java.lang.NullPointerException 03-29 21:04:21.476: E/AndroidRuntime(10437)：at org.altbeacon.beaconreference.MonitoringActivity$4.onFailure(MonitoringActivity.java:199) 03-29 21:04:21.476: E/AndroidRuntime(10437)：at com.loopj.android.http.AsyncHttpResponseHandler.handleMessage(AsyncHttpResponseHandler.java:319) 03-29 21:04:21.476: E/AndroidRuntime(10437)：at com.loopj.android.http.AsyncHttpResponseHandler$ResponderHandler.handleMessage(AsyncHttpResponseHandler.java:138) 03-29 21:04:21.476: E/AndroidRuntime(10437)：at android.os.Handler.dispatchMessage(Handler.java:102) 03-29 21:04:21.476: E/AndroidRuntime(10437)：at android.os.Looper.loop(Looper.java:136) 03-29 21:04:21.476: E/AndroidRuntime(10437)：at android.os.HandlerThread.run(HandlerThread.java:61) 03-29 21:04:21.784: d/蓝牙适配器(10437)：stopLeScan()

Answer 1

因为我不知道哪一行代码在第199行，所以我只能猜测给您一个NPE的是什么。我查过你的密码了。很可能您从REST获得了一个空错误响应，并且它给了您一个NPE。由于onFailure方法除了errorResponse.toString()什么都没有，这应该是问题所在。

您可以像下面这样创建一个变量，并在任何您喜欢的地方使用它，并且您应该将"not known"更改为对您更有意义的其他变量。

String errorText = errorResponse != null ? errorResponse.toString() : "not known";