Android 开发者 Json 和 Pubnub

Question

您好，我编写了一段代码来通过 Pubnub channel 发布 json:

pubnubMessage = new Pubnub("demo", "demo");     
        SupportMapFragment mapFragment = (SupportMapFragment) getSupportFragmentManager()
                    .findFragmentById(id.map);
            map = mapFragment.getMap();
            LocationManager = new MyLocation(this);
            LocationManager.initLocation();
            callback = new LocationCallback() {
                @Override
                public void onNewLocation(Location location, String name) {
                    // *****sending the json string*****
                    JsonSendLocation jsonsendlocation = new JsonSendLocation();
                    jsonsendlocation.setLatitude(location.getLatitude());
                    jsonsendlocation.setLongtitude(location.getLongitude());
                    jsonsendlocation.setUsername(preferencesUtils.getName(
                            getApplicationContext(), preName, key));

                    Gson json = new Gson();
                    String jsonString = json.toJson(jsonsendlocation,
                            JsonSendLocation.class);

                    JSONObject ff;
                    try {
                        ff = new JSONObject(jsonString);
                        publishToPubnub(MY_CHANNEL, ff);                    
                    } catch (JSONException e) {
                        // TODO Auto-generated catch block
                        e.printStackTrace();
                    }

现在我想从我的 Pubnub channel 接收 json 对象，我写道:

Pubnub recieve = new Pubnub("demo", "demo");    
        try {
            recieve.subscribe("MyChannel", new com.pubnub.api.Callback() {

                @Override
                public void successCallback(String arg0, Object arg1) {
                    // TODO Auto-generated method stub

                }
            });
        } catch (PubnubException e1) {
            // TODO Auto-generated catch block
            e1.printStackTrace();
        }

如何从我的 channel 获取 json？

Answer 1

首先，您可以使用 Pubnub 对象的一个​​实例，只需将其声明为实例变量并在 onCreate 中实例化即可。然后您可以使用同一个 Pubnub 对象进行发布和订阅。

private Pubnub mPubNub;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    this.mPubNub = new Pubnub(Constants.PUBLISH_KEY, Constants.SUBSCRIBE_KEY);
    subscribe();
    // publish();
}

现在，当您在 successCallback 中接收对象时，Java 类型转换是完全有效的。我喜欢使用 instanceof 进行检查，这样如果消息由于某种原因无效，我的应用程序就不会崩溃。

public void subscribe(){
    Callback callbacks = new Callback() {
        @Override
        public void successCallback(String channel, Object message) {
            if (message instanceof JSONObject){
                JSONObject json = (JSONObject) message;
                // Handle JSON
            } else if (message instanceof String){
                String str = (String) message;
                // Handle String
            }
            Log.d("PUBNUB", "Channel: " + channel + " Msg: " + message.toString());
        }
    };
    try {
        this.mPubNub.subscribe("MyChannel", callbacks);
    } catch (PubnubException e) {
        e.printStackTrace();
    }
}

如果您有任何其他问题，请告诉我!