无法从本地服务器中的网站检索数据

Question

我有一个Web管理面板，它有一个api，这个api生成Json数据。所以现在我制作了一个Android应用程序来检索这个json数据并在应用程序屏幕上显示它。我现在得到的问题是每当我运行这个应用程序，它正确加载，然后我点击“获取数据”按钮后，asyncTask运行，然后应用程序崩溃几秒钟后。通过日志猫我无法理解这个问题的原因。所以请有人帮我解决这个问题。贝娄是我得到的日志猫视图：

05-31 05:36:33.179: D/AndroidRuntime(973): Shutting down VM
05-31 05:36:33.179: W/dalvikvm(973): threadid=1: thread exiting with uncaught exception (group=0xb4a2fba8)
05-31 05:36:33.289: E/AndroidRuntime(973): FATAL EXCEPTION: main
05-31 05:36:33.289: E/AndroidRuntime(973): Process: com.example.json, PID: 973
05-31 05:36:33.289: E/AndroidRuntime(973): java.lang.NullPointerException
05-31 05:36:33.289: E/AndroidRuntime(973):  at com.example.json.MainActivity$JSONParse.onPostExecute(MainActivity.java:82)
05-31 05:36:33.289: E/AndroidRuntime(973):  at com.arifhaq.json.MainActivity$JSONParse.onPostExecute(MainActivity.java:1)
05-31 05:36:33.289: E/AndroidRuntime(973):  at android.os.AsyncTask.finish(AsyncTask.java:632)
05-31 05:36:33.289: E/AndroidRuntime(973):  at android.os.AsyncTask.access$600(AsyncTask.java:177)
05-31 05:36:33.289: E/AndroidRuntime(973):  at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:645)
05-31 05:36:33.289: E/AndroidRuntime(973):  at android.os.Handler.dispatchMessage(Handler.java:102)
05-31 05:36:33.289: E/AndroidRuntime(973):  at android.os.Looper.loop(Looper.java:136)
05-31 05:36:33.289: E/AndroidRuntime(973):  at android.app.ActivityThread.main(ActivityThread.java:5017)
05-31 05:36:33.289: E/AndroidRuntime(973):  at java.lang.reflect.Method.invokeNative(Native Method)
05-31 05:36:33.289: E/AndroidRuntime(973):  at java.lang.reflect.Method.invoke(Method.java:515)
05-31 05:36:33.289: E/AndroidRuntime(973):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
05-31 05:36:33.289: E/AndroidRuntime(973):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
05-31 05:36:33.289: E/AndroidRuntime(973):  at dalvik.system.NativeStart.main(Native Method)

以下是我的应用程序的主要活动方法：

        public class MainActivity extends Activity {

            Button Btngetdata;
            // URL to get JSON Array
            private static String url = "http://10.0.2.2/bootstrap-dist/adminPanel/";
            // JSON Node Names
            private static final String TAG_USER = "record";
            private static final String TAG_NAME = "Name";
            private static final String TAG_PRICE = "Price";
            private static final String TAG_DESCRIPTION = "Description";

            JSONArray user = null;

            @Override
            protected void onCreate(Bundle savedInstanceState) {
                super.onCreate(savedInstanceState);
                setContentView(R.layout.activity_main);
                Btngetdata = (Button) findViewById(R.id.getdata);
                Btngetdata.setOnClickListener(new View.OnClickListener() {
                    @Override
                    public void onClick(View view) {
                        new JSONParse().execute();
                    }
                });
            }

            private class JSONParse extends AsyncTask<String, String, JSONObject> {
                private ProgressDialog pDialog;

                @Override
                protected void onPreExecute() {
                    super.onPreExecute();
                    pDialog = new ProgressDialog(MainActivity.this);
                    pDialog.setMessage("Getting Data ...");
                    pDialog.setIndeterminate(false);
                    pDialog.setCancelable(true);
                    pDialog.show();
                }

                @Override
                protected JSONObject doInBackground(String... args) {
                    JSONParser jParser = new JSONParser();
                    // Getting JSON from URL
                    JSONObject json = jParser.getJSONFromUrl(url);
                    return json;
                }

                @Override
                protected void onPostExecute(JSONObject json) {
                    pDialog.dismiss();
                    JSONObject c=null;
                    try {
                        // Getting JSON Array
                        user = json.getJSONArray(TAG_USER);
                        for(int i=0;i<user.length();i++){
                             c = user.getJSONObject(i);
                            // Storing JSON item in a Variable
                                String name = c.getString(TAG_NAME);
                                String price = c.getString(TAG_PRICE);  
                                String description = c.getString(TAG_DESCRIPTION);  

                                Toast.makeText(MainActivity.this, name+"\n"+price+"\n"+description, Toast.LENGTH_SHORT).show();


                        }


                    } catch (JSONException e) {
                        e.printStackTrace();
                    }
                }
            }
        }