Question

正如标题所说，我想要构建的是一个显示特定REST服务响应的android 小部件。我是android的新手。因此，我使用this great tutorial来构建窗口小部件并从android服务更新它。然后我使用基于this post的volley library来从REST服务器检索数据。以下是我的服务OnStart方法的代码：

@Override
    public void onStart(Intent intent, int startId) {
        // create some random data

        AppWidgetManager appWidgetManager = AppWidgetManager.getInstance(this
                .getApplicationContext());

        int[] allWidgetIds = intent
                .getIntArrayExtra(AppWidgetManager.EXTRA_APPWIDGET_IDS);

        ComponentName thisWidget = new ComponentName(getApplicationContext(),
                MyWidgetProvider.class);
        int[] allWidgetIds2 = appWidgetManager.getAppWidgetIds(thisWidget);
        applicationContext = this.getApplicationContext();

        for (int widgetId : allWidgetIds) {
            number = (new Random().nextInt(100));

            Log.w("WidgetExample", "Showing:" + String.valueOf(number));
            remoteViews = new RemoteViews(applicationContext.getPackageName(),
                    R.layout.widget_layout);

            // Set the text
            remoteViews.setTextViewText(R.id.update, String.valueOf(number));

            /////////////////////////////////////////////////////////
            /*// Get the data from the rest service
            RequestQueue queue = Volley.newRequestQueue(this);
            // String url =
            // "https://www.googleapis.com/customsearch/v1?key=AIzaSyBmSXUzVZBKQv9FJkTpZXn0dObKgEQOIFU&cx=014099860786446192319:t5mr0xnusiy&q=AndroidDev&alt=json&searchType=image";
            String url = "http://develop1.med.auth.gr:8080/envapp/json?date=2014-3-14";

            JsonObjectRequest jsObjRequest = new JsonObjectRequest(
                    Request.Method.GET, url, null,
                    new Response.Listener<JSONObject>() {

                        @Override
                        public void onResponse(JSONObject response) {
                            Log.w("WidgetExample",
                                    "Response => " + response.toString());
                            // Set the text\
                            remoteViews.setTextViewText(R.id.update,
                                    "Response => " + response.toString());
                        }
                    }, new Response.ErrorListener() {

                        @Override
                        public void onErrorResponse(VolleyError error) {
                            // TODO Auto-generated method stub
                            Log.w("WidgetExample",
                                    "Error => " + error.toString());
                            remoteViews.setTextViewText(R.id.update,
                                    "Error => " + error.toString());
                        }
                    });

            queue.add(jsObjRequest);*/
            ////////////////////////////////////////////////////////////////////////////

            // Register an onClickListener
            Intent clickIntent = new Intent(this.getApplicationContext(),
                    MyWidgetProvider.class);

            clickIntent.setAction(AppWidgetManager.ACTION_APPWIDGET_UPDATE);
            clickIntent.putExtra(AppWidgetManager.EXTRA_APPWIDGET_IDS,
                    allWidgetIds);

            PendingIntent pendingIntent = PendingIntent.getBroadcast(
                    getApplicationContext(), 0, clickIntent,
                    PendingIntent.FLAG_UPDATE_CURRENT);
            remoteViews.setOnClickPendingIntent(R.id.update, pendingIntent);
            appWidgetManager.updateAppWidget(widgetId, remoteViews);
        }
        stopSelf();

        super.onStart(intent, startId);
    }

如您所见，我已经注释掉了REST服务调用代码。这个片段，播放得很好。它使用随机数更新UI。如果我取消注释REST服务调用代码，我可以在LogCat中看到服务的响应，但我无法更新UI 。我尝试过同步调用来获取REST服务响应，但没有运气。

有人可以告诉我为什么我无法从响应事件处理程序更新UI吗？这可能吗？我怎么能这样做？有人能给我指教吗？

Answer 1

我发现了问题所在。我必须调用updateAppWidget方法。该方法应如下......

@Override
public void onStart(Intent intent, int startId) {
    appWidgetManager = AppWidgetManager.getInstance(this
            .getApplicationContext());

    int[] allWidgetIds = intent
            .getIntArrayExtra(AppWidgetManager.EXTRA_APPWIDGET_IDS);

    ComponentName thisWidget = new ComponentName(getApplicationContext(),
            MyWidgetProvider.class);
    int[] allWidgetIds2 = appWidgetManager.getAppWidgetIds(thisWidget);
    Log.w(LOG, "From Intent" + String.valueOf(allWidgetIds.length));
    Log.w(LOG, "Direct" + String.valueOf(allWidgetIds2.length));

    for (int widgetId : allWidgetIds) {
        number = (new Random().nextInt(100));
        widgetIdToUse = widgetId;

        Log.w("WidgetExample", "Showing:" + String.valueOf(number));
        remoteViews = new RemoteViews(this.getApplicationContext()
                .getPackageName(), R.layout.widget_layout);

        // Get the data from the rest service
        RequestQueue queue = Volley.newRequestQueue(this);

        // String url =
        // "https://www.googleapis.com/customsearch/v1?key=AIzaSyBmSXUzVZBKQv9FJkTpZXn0dObKgEQOIFU&cx=014099860786446192319:t5mr0xnusiy&q=AndroidDev&alt=json&searchType=image";
        String url = "http://develop1.med.auth.gr:8080/envapp/json?date=2014-3-14";

        JsonObjectRequest jsObjRequest = new JsonObjectRequest(
                Request.Method.GET, url, null,
                new Response.Listener<JSONObject>() {

                    @Override
                    public void onResponse(JSONObject response) {
                        Log.w("WidgetExample",
                                "Response => " + response.toString());
                        // Set the text\
                        try {
                            remoteViews.setTextViewText(R.id.update,
                                    response.getString("gentoday"));
                        } catch (JSONException e) {
                            // TODO Auto-generated catch block
                            e.printStackTrace();
                        }
                        appWidgetManager.updateAppWidget(widgetIdToUse, remoteViews);
                    }
                }, new Response.ErrorListener() {

                    @Override
                    public void onErrorResponse(VolleyError error) {
                        // TODO Auto-generated method stub
                        Log.w("WidgetExample",
                                "Error => " + error.toString());
                        remoteViews.setTextViewText(R.id.update,
                                "Error => " + error.toString());
                        appWidgetManager.updateAppWidget(widgetIdToUse, remoteViews);
                    }
                });
        queue.add(jsObjRequest);

        // Register an onClickListener
        Intent clickIntent = new Intent(this.getApplicationContext(),
                MyWidgetProvider.class);

        clickIntent.setAction(AppWidgetManager.ACTION_APPWIDGET_UPDATE);
        clickIntent.putExtra(AppWidgetManager.EXTRA_APPWIDGET_IDS,
                allWidgetIds);

        PendingIntent pendingIntent = PendingIntent.getBroadcast(
                getApplicationContext(), 0, clickIntent,
                PendingIntent.FLAG_UPDATE_CURRENT);
        remoteViews.setOnClickPendingIntent(R.id.update, pendingIntent);
        appWidgetManager.updateAppWidget(widgetId, remoteViews);
    }
    stopSelf();

    super.onStart(intent, startId);
}

显示REST服务响应的小组件

1 个答案: