Android:无法通过应用程序调用Java Web服务

我正在尝试使用url通过android应用程序调用web服务，但我收到的错误是resonse http代码为0，onFailure内容为null。我可以使用移动浏览器打开和传递参数，但当我运行我的应用程序时，它会在onFailure方法中抛出else部分的错误“发生意外错误！[大多数

 AsyncHttpClient client = new AsyncHttpClient();
    client.get("http://198.168.43.250:8081/TrekServerTest2/rest/register/doregister",params ,new AsyncHttpResponseHandler() {
        // When the response returned by REST has Http response code '200'
        @Override
        public void onSuccess(String response) {
            // Hide Progress Dialog
            prgDialog.hide();
            try {
                // JSON Object
                JSONObject obj = new JSONObject(response);
                // When the JSON response has status boolean value assigned with true
                if(obj.getBoolean("status")){
                    // Set Default Values for Edit View controls
                    setDefaultValues();
                    // Display successfully registered message using Toast
                    Toast.makeText(getApplicationContext(), "You are successfully registered!", Toast.LENGTH_LONG).show();
                }
                // Else display error message
                else{
                    //errorMsg.setText(obj.getString("error_msg"));
                    Toast.makeText(getApplicationContext(), obj.getString("error_msg"), Toast.LENGTH_LONG).show();
                }
            } catch (JSONException e) {
                // TODO Auto-generated catch block
                Toast.makeText(getApplicationContext(), "Error Occured [Server's JSON response might be invalid]!", Toast.LENGTH_LONG).show();
                e.printStackTrace();

            }
        }
        // When the response returned by REST has Http response code other than '200'
        @Override
        public void onFailure(int statusCode, Throwable error,
                              String content) {
            Toast.makeText(getApplicationContext(), ""+statusCode+ "e:"+content, Toast.LENGTH_LONG).show();
            // Hide Progress Dialog
            prgDialog.hide();
            // When Http response code is '404'
            if(statusCode == 404){
                Toast.makeText(getApplicationContext(), "Requested resource not found", Toast.LENGTH_LONG).show();
            }
            // When Http response code is '500'
            else if(statusCode == 500){
                Toast.makeText(getApplicationContext(), "Something went wrong at server end", Toast.LENGTH_LONG).show();
            }
            // When Http response code other than 404, 500
            else{
                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();
            }
        }
    });

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您好，在清单中添加internet权限？是的，我已添加该权限