使用谷歌云消息传递推送Android和PHP脚本的通知

Question

我已经完成了谷歌开发者页面上提到的所有说明，但我是新手推送通知，所以我无法理解我需要为sendregistrationtoserver（）函数添加什么代码。而且我想知道我需要做的相应的PHP脚本来获取注册ID和发送推送消息。 提前谢谢。

package com.babajideal.babajideal;

import android.app.IntentService;
import android.content.Intent;
import android.content.SharedPreferences;
import android.preference.PreferenceManager;
import android.support.v4.content.LocalBroadcastManager;

import com.google.android.gms.gcm.GcmPubSub;
import com.google.android.gms.gcm.GoogleCloudMessaging;
import com.google.android.gms.iid.InstanceID;

import java.io.IOException;

public class RegisterationIntentService extends IntentService {

    private static final String TAG = "RegIntentService";
    private static final String[] TOPICS = {"global"};

    public RegisterationIntentService() {
        super(TAG);
    }

    @Override
    protected void onHandleIntent(Intent intent) {
        SharedPreferences sharedPreferences = PreferenceManager.getDefaultSharedPreferences(this);
        InstanceID instanceID = InstanceID.getInstance(this);
        try {
            String token = instanceID.getToken(getResources().getString(R.string.gcm_senderId), GoogleCloudMessaging.INSTANCE_ID_SCOPE,null);
            sendRegistrationToServer(token);
            subscribeTopics(token);
            sharedPreferences.edit().putBoolean(QuickstartPreferences.SENT_TOKEN_TO_SERVER, true).apply();
        } catch (IOException e) {
            e.printStackTrace();
            sharedPreferences.edit().putBoolean(QuickstartPreferences.SENT_TOKEN_TO_SERVER, false).apply();
        }
        Intent registrationComplete = new Intent(QuickstartPreferences.REGISTRATION_COMPLETE);
        LocalBroadcastManager.getInstance(this).sendBroadcast(registrationComplete);
    }
    private void subscribeTopics(String token) throws IOException {
        GcmPubSub pubSub = GcmPubSub.getInstance(this);
        for (String topic : TOPICS) {
            pubSub.subscribe(token, "/topics/" + topic, null);
        }
    }
    private void sendRegistrationToServer(String token) {
        // Add custom implementation, as needed.
    }
}