从 Android 通知中的 URL 加载图像

问题描述 投票：0回答：9

在我的 Android 应用程序中，我想动态设置将从 URL 加载的通知图标。为此，我在 

setLargeIcon
中使用了NotificationBuilder 的 
receiver
属性。

我提供了很多链接并尝试了各种解决方案，但我无法获得所需的输出。尽管我从 URL 下载了该图像并在通知中设置了该位图，但它并未显示。相反，它将 

setSmallIcon
图像显示为大图标。我不知道我哪里错了。我在这里发布我的代码。请帮我解决这个问题。谢谢你。

代码：

@SuppressLint("NewApi")
public class C2DMMessageReceiver extends BroadcastReceiver {

    @Override
    public void onReceive(Context context, Intent intent) {
        String action = intent.getAction();
        if ("com.google.android.c2dm.intent.RECEIVE".equals(action)) {
            Log.e("C2DM", "received message");
            final String fullName = intent.getStringExtra("message");
            final String payload1 = intent.getStringExtra("message1");
            final String payload2 = intent.getStringExtra("message2");
            final String userImage = intent.getStringExtra("userImage");

            Log.e("userImage Url :", userImage); //it shows correct url

            new sendNotification(context)
                    .execute(fullName, payload1, userImage);
        }
    }

private class sendNotification extends AsyncTask<String, Void, Bitmap> {

        Context ctx;
        String message;

        public sendNotification(Context context) {
            super();
            this.ctx = context;
        }

        @Override
        protected Bitmap doInBackground(String... params) {

            InputStream in;
            message = params[0] + params[1];
            try {

                in = new URL(params[2]).openStream();
                Bitmap bmp = BitmapFactory.decodeStream(in);
                return bmp;

            } catch (MalformedURLException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            }
            return null;
        }

        @Override
        protected void onPostExecute(Bitmap result) {

            super.onPostExecute(result);
            try {
                NotificationManager notificationManager = (NotificationManager) ctx
                        .getSystemService(Context.NOTIFICATION_SERVICE);

                Intent intent = new Intent(ctx, NotificationsActivity.class);
                intent.putExtra("isFromBadge", false);


                Notification notification = new Notification.Builder(ctx)
                        .setContentTitle(
                                ctx.getResources().getString(R.string.app_name))
                        .setContentText(message)
                        .setSmallIcon(R.drawable.ic_launcher)
                        .setLargeIcon(result).build();

                // hide the notification after its selected
                notification.flags |= Notification.FLAG_AUTO_CANCEL;

                notificationManager.notify(1, notification);

            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    }
android bitmap google-cloud-messaging android-notifications android-notification-bar
9个回答
47
投票

我更改了代码如下，现在可以工作了：

private class sendNotification extends AsyncTask<String, Void, Bitmap> {

        Context ctx;
        String message;

        public sendNotification(Context context) {
            super();
            this.ctx = context;
        }

        @Override
        protected Bitmap doInBackground(String... params) {

            InputStream in;
            message = params[0] + params[1];
            try {

                  URL url = new URL(params[2]);
                  HttpURLConnection connection = (HttpURLConnection)url.openConnection();
                  connection.setDoInput(true);
                  connection.connect();
                  in = connection.getInputStream();
                  Bitmap myBitmap = BitmapFactory.decodeStream(in);
                  return myBitmap;
            } catch (MalformedURLException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            }
            return null;
        }

        @Override
        protected void onPostExecute(Bitmap result) {

            super.onPostExecute(result);
            try {
                NotificationManager notificationManager = (NotificationManager) ctx
                        .getSystemService(Context.NOTIFICATION_SERVICE);

                Intent intent = new Intent(ctx, NotificationsActivity.class);
                intent.putExtra("isFromBadge", false);


                Notification notification = new Notification.Builder(ctx)
                        .setContentTitle(
                                ctx.getResources().getString(R.string.app_name))
                        .setContentText(message)
                        .setSmallIcon(R.drawable.ic_launcher)
                        .setLargeIcon(result).build();

                // hide the notification after its selected
                notification.flags |= Notification.FLAG_AUTO_CANCEL;

                notificationManager.notify(1, notification);

            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    }
40
投票

你可以使用 Glide 来做到这一点，如下所示：

val notificationBuilder = NotificationCompat.Builder(this, channelId)
        .setSmallIcon(R.drawable.ic_message)
        .setContentTitle("title")
        .setContentText("text")

val notificationManager = getSystemService(Context.NOTIFICATION_SERVICE) as NotificationManager

val futureTarget = Glide.with(this)
        .asBitmap()
        .load(photoUrl)
        .submit()

val bitmap = futureTarget.get()
notificationBuilder.setLargeIcon(bitmap)

Glide.with(this).clear(futureTarget)

notificationManager.notify(0, notificationBuilder.build())

38
投票

如何实现BigPicture风格通知：

奇迹是由

.setStyle(new Notification.BigPictureStyle().bigPicture(result))
创造的：

我已经这样做了：

通过AsyncTask生成通知：

new generatePictureStyleNotification(this,"Title", "Message", 
                 "http://api.androidhive.info/images/sample.jpg").execute();

异步任务：

public class generatePictureStyleNotification extends AsyncTask<String, Void, Bitmap> {

        private Context mContext;
        private String title, message, imageUrl;

        public generatePictureStyleNotification(Context context, String title, String message, String imageUrl) {
            super();
            this.mContext = context;
            this.title = title;
            this.message = message;
            this.imageUrl = imageUrl;
        }

        @Override
        protected Bitmap doInBackground(String... params) {

            InputStream in;
            try {
                URL url = new URL(this.imageUrl);
                HttpURLConnection connection = (HttpURLConnection) url.openConnection();
                connection.setDoInput(true);
                connection.connect();
                in = connection.getInputStream();
                Bitmap myBitmap = BitmapFactory.decodeStream(in);
                return myBitmap;
            } catch (MalformedURLException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            }
            return null;
        }

        @TargetApi(Build.VERSION_CODES.JELLY_BEAN)
        @Override
        protected void onPostExecute(Bitmap result) {
            super.onPostExecute(result);

            Intent intent = new Intent(mContext, MyOpenableActivity.class);
            intent.putExtra("key", "value");
            PendingIntent pendingIntent = PendingIntent.getActivity(mContext, 100, intent, PendingIntent.FLAG_ONE_SHOT);

            NotificationManager notificationManager = (NotificationManager) mContext.getSystemService(Context.NOTIFICATION_SERVICE);
            Notification notif = new Notification.Builder(mContext)
                    .setContentIntent(pendingIntent)
                    .setContentTitle(title)
                    .setContentText(message)
                    .setSmallIcon(R.mipmap.ic_launcher)
                    .setLargeIcon(result)
                    .setStyle(new Notification.BigPictureStyle().bigPicture(result))
                    .build();
            notif.flags |= Notification.FLAG_AUTO_CANCEL;
            notificationManager.notify(1, notif);
        }
    }
26
投票

Kotlin 和协程中的最佳答案。此方法将位图应用于 

builder
而不是直接赋值，当然如果位图可用的话。这很好，因为如果 url 错误，它将被捕获在 try/catch 中。

fun applyImageUrl(
    builder: NotificationCompat.Builder, 
    imageUrl: String
) = runBlocking {
    val url = URL(imageUrl)

    withContext(Dispatchers.IO) {
        try {
            val input = url.openStream()
            BitmapFactory.decodeStream(input)
        } catch (e: IOException) {
            null
        }
    }?.let { bitmap ->
        builder.setLargeIcon(bitmap)
    }
}

使用 Kotlin 和 RxJava

fun applyImageUrl(
    builder: NotificationCompat.Builder,
    imageUrl: String
) {
    val url = URL(imageUrl)

    Single.create<Bitmap> { emitter ->
        try {
            val input = url.openStream()
            val bitmap = BitmapFactory.decodeStream(input)
            emitter.onSuccess(bitmap)
        } catch (e: Exception) {
            emitter.onError(e)
        }
    }.subscribeOn(Schedulers.io())
        .observeOn(AndroidSchedulers.mainThread())
        .subscribe(
            {
                builder.setLargeIcon(it)
            }, {
                Timber.e("error generating bitmap for notification")
            }
        )
}
10
投票

由于图像是从互联网加载的，因此应该在后台线程中异步完成。使用异步任务或 Glide（以实现高效的图像加载）。

要加载图像通知，您需要使用“NotificationCompat.BigPictureStyle()”。这需要一个位图（必须从图像网址中提取）

Glide 的大部分 API 和方法现已弃用。 下面是与 Glide 4.9 和 Android 10 一起使用的情况。

 // Load bitmap from image url on background thread and display image notification
        private void getBitmapAsyncAndDoWork(String imageUrl) {

            final Bitmap[] bitmap = {null};

            Glide.with(getApplicationContext())
                    .asBitmap()
                    .load(imageUrl)
                    .into(new CustomTarget<Bitmap>() {
                        @Override
                        public void onResourceReady(@NonNull Bitmap resource, @Nullable Transition<? super Bitmap> transition) {

                            bitmap[0] = resource;
                            // TODO Do some work: pass this bitmap
                            displayImageNotification(bitmap[0]);
                        }

                        @Override
                        public void onLoadCleared(@Nullable Drawable placeholder) {
                        }
                    });
        }

显示图像通知一次，位图已准备好。

private void displayImageNotification(Bitmap bitmap) {

      NotificationCompat.Builder builder = new NotificationCompat.Builder(getApplicationContext(), getChannelId());
            builder
                    .setContentTitle(title)
                    .setContentText(subtext)
                    .setDefaults(Notification.DEFAULT_LIGHTS | Notification.DEFAULT_VIBRATE)
                    .setSmallIcon(SMALL_ICON)
                    .setPriority(NotificationCompat.PRIORITY_DEFAULT)
                    .setColor(getApplicationContext().getColor(color))
                    .setAutoCancel(true)
                    .setOngoing(false)
                    .setOnlyAlertOnce(true)
                    .setContentIntent(pendingIntent)
                     .setStyle(
                     new NotificationCompat.BigPictureStyle().bigPicture(bitmap))
                    .setPriority(Notification.PRIORITY_HIGH);

        getManager().notify(tag, id, builder.build());
}
6
投票

我知道已经给出了一个很好的答案，所以让我们看看是否可以使其更容易理解和实施。
------------------理论------------------------------------
这个问题可以抽象为两步解决方案，即
1）从URL获取图像
2）解码图像并传递给通知生成器

1）从 URL 获取图像

InputStream in = new URL("Img URL goes here eg. http://gg.com/profile.jpg").openStream();

2）解码并传递给通知

Bitmap bmp = null;
#创建一个空的bmp容器，用于保存解码后的img 
bmp = BitmapFactory.decodeStream(in);
# 将图像保存到容器中

瞧！ 一旦构建图像并将其保存在变量 bmp 中，您就可以在通知构建器上调用它 

.setLargeIcon(bmp)


--------实施----------------
Android studio 会鼓励你用 try catch 包装你的代码，这样最终的产品就会像这样。

Bitmap bmp = null;
try {
    InputStream in = new URL("url goes here").openStream();
    bmp = BitmapFactory.decodeStream(in);
} catch (IOException e) {
    e.printStackTrace();
}

一旦获得了 bmp，您就可以在通知生成器中将其称为

NotificationCompat.Builder mBuilder = new NotificationCompat.Builder(this, CHANNEL_ID)
            .setSmallIcon(R.drawable.ic_launcher)
            .setContentText("title")
            .setContentText("text goes here")
            .setLargeIcon(bmp)
            .setAutoCancel(true);
0
投票

使用毕加索图书馆。

               Target target = new Target() {
                    @Override
                    public void onBitmapLoaded(Bitmap bitmap, Picasso.LoadedFrom from) {
                        largeIcon=bitmap;
                    }

                    @Override
                    public void onBitmapFailed(Drawable errorDrawable) {
                    }

                    @Override
                    public void onPrepareLoad(Drawable placeHolderDrawable) {
                    }
                };

                Picasso.with(this).load("url").into(target); 





               NotificationCompat.Builder notificationBuilder =
                    new NotificationCompat.Builder(this, channelId)
                            .setSmallIcon(R.drawable.icon)
                            .setContentTitle(msg.getString("title"))
                            .setContentText(msg.getString("msg"))
                            .setAutoCancel(true)
                            .setSound(defaultSoundUri)
                            .setLargeIcon(largeIcon)
                            .setContentIntent(pendingIntent);
0
投票

由于我找不到 Picasso 的任何工作解决方案，我将在下面发布使用 Picasso 的完整且有效的示例（2020 年 7 月）。

它立即发送通知，然后在加载 setLargeIcon() 的图像时更新通知。通常这非常快，并且在大多数情况下用户应该只看到通知的更新版本。

private void sendNotification(String message, String title, final String photoUrl) {
    Intent intent = new Intent(this, MainActivity.class);
    intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
    PendingIntent pendingIntent = PendingIntent.getActivity(this, 0, intent,
            PendingIntent.FLAG_ONE_SHOT);

    final NotificationCompat.Builder notificationBuilder =
            new NotificationCompat.Builder(this, CHANNEL_ID)
                    .setSmallIcon(R.drawable.wbib_transp_512)
                    .setContentTitle(title)
                    .setContentText(message)
                    .setAutoCancel(true)
                    .setPriority(NotificationCompat.PRIORITY_HIGH)
                    .setCategory(NotificationCompat.CATEGORY_MESSAGE)
                    .setContentIntent(pendingIntent);

    final NotificationManager notificationManager =
            (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);

    notificationManager.notify(0, notificationBuilder.build());

    final Handler uiHandler = new Handler(Looper.getMainLooper());
    uiHandler.post(new Runnable() {
        @Override
        public void run() {
            Picasso.get()
                    .load(photoUrl)
                    .resize(200, 200)
                    .into(new Target() {
                        @Override
                        public void onBitmapLoaded(final Bitmap bitmap, final Picasso.LoadedFrom from) {
                            notificationBuilder.setLargeIcon(bitmap);
                            notificationManager.notify(0, notificationBuilder.build());
                        }

                        @Override
                        public void onBitmapFailed(Exception e, final Drawable errorDrawable) {
                            // Do nothing?
                        }

                        @Override
                        public void onPrepareLoad(final Drawable placeHolderDrawable) {
                            // Do nothing?
                        }
                    });
        }
    });


}
0
投票

RxJava 和毕加索方式

private fun bigImageNotification(ctx: Context, title: String, msg: String, imgUrl: String): Disposable? {
    return Observable.fromCallable {
        Picasso.get().load(imgUrl).get()
    }
            .subscribeOn(Schedulers.io())
            .observeOn(AndroidSchedulers.mainThread())
            .subscribe({
                createNotification(ctx, title, msg, it)
            }, {it.printStackTrace()})
}

private fun createNotification(ctx: Context, title: String, msg: String, img: Bitmap?) {
    val b = Notification.Builder(ctx)
    b.setAutoCancel(true)
            .setSmallIcon(R.mipmap.ic_launcher)
            .setContentTitle(title)
            .setContentText(msg)
            .setStyle(Notification.BigPictureStyle().bigPicture(img))
    val notificationManager = ctx.getSystemService(Context.NOTIFICATION_SERVICE) as NotificationManager
    notificationManager.notify(1000, b.build())
}

使用方法

bigImageNotification(context, "title", "msg", "https://www.google.com/images/branding/googlelogo/1x/googlelogo_color_272x92dp.png")
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