android如何在特定的json值发生变化时接收通知

Question

其实我有json url，我正在开发阅读这个json url的应用程序。 如果tr_id等于我的值并且状态值更改为＆＃34;付费＆＃34;，我想收到通知。 我做了很多搜索，但我没有任何解决方案。 我试图使广播接收器监听互联网连接并加载json url值并在所有条件都是真的时发出通知。 但它不再工作，甚至吐司的消息，这里没有显示是我的尝试。

这是我的NotificationReceiver类

import android.app.Notification;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.SharedPreferences;
import android.net.ConnectivityManager;
import android.net.NetworkInfo;
import android.support.v4.app.NotificationCompat;
import android.support.v4.app.NotificationManagerCompat;
import android.util.Log;
import android.widget.RemoteViews;
import android.widget.Toast;

import com.apk4android.resturantapp.R;

import retrofit2.Call;
import retrofit2.Callback;

public class NotificationReceiver extends BroadcastReceiver {

private Context context;

@Override
public void onReceive(Context context, Intent intent) {

    this.context = context;
    Toast.makeText(context, "Receiver running", Toast.LENGTH_SHORT).show();

    if (isOnline(context)) {
        notificationListener();
    }

}


SharedPreferences sp;

private void notificationListener() {
    sp = context.getSharedPreferences("current_tr_id",         Context.MODE_PRIVATE);

    RegisterAPI2 registerAPI =         ApiClient.getApiClient2().create(RegisterAPI2.class);

    Call<TrResponse> req = registerAPI.getStatus();
    req.enqueue(new Callback<TrResponse>() {
                    @Override
                    public void onResponse(Call<TrResponse> call,     
retrofit2.Response<TrResponse> response) {

                        TrResponse post = response.body();

                        String tr_id = post.getTr_number().toString();
                        String status = post.getStatus().toString();
                        // make sure the tr_id of current order == tr_id of json
                        String currentID = sp.getString("currentID", "3");
                        Log.d("tr_id", "Current tr_id comes from user that paid the order = " + currentID);


                        if (status.equals("Paid") && !tr_id.equals("3") && tr_id.equals(currentID)) {
                            // make notification
                            notifyUser();

                        }

                    }

                    @Override
                    public void onFailure(Call<TrResponse> call, Throwable t) {

                        Log.d("TTTT CallBack", " Throwable is " + t + " Call  " + call.toString());

                    }

                }
    );

}

public boolean isOnline(Context context) {

    ConnectivityManager cm = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
    NetworkInfo netInfo = cm.getActiveNetworkInfo();
    //should check null because in airplane mode it will be null
    return (netInfo != null && netInfo.isConnected());
}

private void notifyUser() {
    RemoteViews contentView = new RemoteViews(context.getPackageName(), R.layout.notification);
    contentView.setImageViewResource(R.id.image, R.mipmap.ic_launcher);
    contentView.setTextViewText(R.id.title, "Custom notification");
    contentView.setTextViewText(R.id.text, "This is a custom layout");

    NotificationCompat.Builder mBuilder = new NotificationCompat.Builder(context)
            .setSmallIcon(R.drawable.icon)
            .setContent(contentView);

    Notification notification = mBuilder.build();
    notification.flags |= Notification.FLAG_AUTO_CANCEL;
    notification.defaults |= Notification.DEFAULT_SOUND;
    notification.defaults |= Notification.DEFAULT_VIBRATE;

    NotificationManagerCompat notificationManager = NotificationManagerCompat.from(context);
    notificationManager.notify(1, notification);

    }

   }

Minifest

 <receiver android:name=".notification.NotificationReceiver"
        android:enabled="true">
        <intent-filter>
            <action android:name="android.net.conn.CONNECTIVITY_CHANGE" />
            <action android:name="android.net.wifi.WIFI_STATE_CHANGED" />
            <action android:name="android.net.wifi.STATE_CHANGE" />
        </intent-filter>
    </receiver>

抱歉我的英文。 所以请我。 谢谢。