使用异步类将 gps 位置发送到服务器时应用程序崩溃

Question

我想将我的 gps 位置发送到服务器，但它在 doinbackground 方法中显示错误，在显示的 logcat 经度、纬度和设备 ID 上以及在该应用程序崩溃之后。 这个类显示我的异步类。

  private class MyAsyncTask extends AsyncTask<Void, Void, Void>
                {
                        ProgressDialog mProgressDialog;
                        @Override
                        protected void onPostExecute(Void result) {
                            mProgressDialog.dismiss();
                        }

                        @Override
                        protected void onPreExecute() {
                            mProgressDialog = ProgressDialog.show(MainActivity.this, "Loading...", "Data is Loading...");
                        }

                        @Override
                        protected Void doInBackground(Void... params) {

                            HttpClient httpclient = new DefaultHttpClient();

                             GPSTracker gps = new GPSTracker(MainActivity.this);
                             String lat=Double.toString(gps.getLatitude());
                             String lon=Double.toString(gps.getLongitude());

                            String url="http://m4yank.com/inhouse/mhere/api/api.php?q=track&uid=" +MainActivity.getDeviceId(MainActivity.this)+"&lat=" + lat + "&longt=" + lon;
                            HttpPost httpost = new HttpPost("url");
                           Log.d("Latitude", ""+lat);
                           Log.d("Longitude", ""+lon);
                           Log.d("Device id", ""+MainActivity.getDeviceId(MainActivity.this));

                            try {

                                List<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>(2);
                                nameValuePairs.add(new BasicNameValuePair("latitude", lat));
                                nameValuePairs.add(new BasicNameValuePair("longitude", lon)); 
                                httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs));
                                httpclient.execute(httppost);
                                //Log.d("Latitude", ""+lat);
                               // Log.d("Longitude", ""+lon);
                              } 
                             catch (ClientProtocolException e) {
                                 // TODO Auto-generated catch block
                                 e.printStackTrace();
                             } 
                             catch (IOException e) {
                                 // TODO Auto-generated catch block
                                 e.printStackTrace();
                             }



                            return null;
                        }



                    }

在 logcat 中显示错误：

  12-03 21:22:37.540: E/AndroidRuntime(2410): FATAL EXCEPTION: AsyncTask #1
12-03 21:22:37.540: E/AndroidRuntime(2410): java.lang.RuntimeException: An error occured while executing doInBackground()
12-03 21:22:37.540: E/AndroidRuntime(2410):     at android.os.AsyncTask$3.done(AsyncTask.java:299)
12-03 21:22:37.540: E/AndroidRuntime(2410):     at java.util.concurrent.FutureTask.finishCompletion(FutureTask.java:352)
12-03 21:22:37.540: E/AndroidRuntime(2410):     at java.util.concurrent.FutureTask.setException(FutureTask.java:219)
12-03 21:22:37.540: E/AndroidRuntime(2410):     at java.util.concurrent.FutureTask.run(FutureTask.java:239)
12-03 21:22:37.540: E/AndroidRuntime(2410):     at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:230)
12-03 21:22:37.540: E/AndroidRuntime(2410):     at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1080)
12-03 21:22:37.540: E/AndroidRuntime(2410):     at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:573)
12-03 21:22:37.540: E/AndroidRuntime(2410):     at java.lang.Thread.run(Thread.java:856)
12-03 21:22:37.540: E/AndroidRuntime(2410): Caused by: java.lang.IllegalStateException: Target host must not be null, or set in parameters. scheme=null, host=null, path=url
12-03 21:22:37.540: E/AndroidRuntime(2410):     at org.apache.http.impl.client.DefaultRequestDirector.determineRoute(DefaultRequestDirector.java:591)
12-03 21:22:37.540: E/AndroidRuntime(2410):     at org.apache.http.impl.client.DefaultRequestDirector.execute(DefaultRequestDirector.java:293)
12-03 21:22:37.540: E/AndroidRuntime(2410):     at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:555)
12-03 21:22:37.540: E/AndroidRuntime(2410):     at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:487)
12-03 21:22:37.540: E/AndroidRuntime(2410):     at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:465)
12-03 21:22:37.540: E/AndroidRuntime(2410):     at com.example.gps.MainActivity$MyAsyncTask.doInBackground(MainActivity.java:251)
12-03 21:22:37.540: E/AndroidRuntime(2410):     at com.example.gps.MainActivity$MyAsyncTask.doInBackground(MainActivity.java:1)
12-03 21:22:37.540: E/AndroidRuntime(2410):     at android.os.AsyncTask$2.call(AsyncTask.java:287)
12-03 21:22:37.540: E/AndroidRuntime(2410):     at java.util.concurrent.FutureTask.run(FutureTask.java:234)
12-03 21:22:37.540: E/AndroidRuntime(2410): 

Answer 1

应该有一条错误消息说明错误发生的原因或位置。 我假设您已在清单中设置了所有需要的权限...

Answer 2

line 258: httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs));

那么httppost 就是null，因为你在这条线上得到了NullPointerException。我没有看到 httppost 是在哪里定义的，更不用说初始化了。