Glide cache image on disk on background thread

问题

I want to use Glide to eagerly download images and cache them on disk for a future use. I want to call this functionality from a background thread.

I've read Glide's caching documentation, but it doesn't explain how to download the image without having an actual target right now. Then I found this issue and tried to use a similar approach, but whatever I try I get this exception:

java.lang.IllegalArgumentException: You must call this method on the main thread

So, how can I tell Glide to cache an image from a background thread?

EDIT: I really want to call Glide's methods on background thread. I know that I can use Handler and other ways to offload it to UI thread, but that's not what I'm asking.

回答1:

GlideApp.with(context)
    .downloadOnly()
    .diskCacheStrategy(DiskCacheStrategy.DATA) // Cache resource before it's decoded
    .load(url)
    .submit(Target.SIZE_ORIGINAL, Target.SIZE_ORIGINAL)
    .get() // Called on background thread

回答2:

If want to load images in cache for future use in background thread then Glide have this functionality

here how you can do this

 //here i passing application context so our glide tie itself with application lifecycle

FutureTarget<File> future = Glide.with(getApplicationContext()).downloadOnly().load("your_image_url").submit();

now if you want to retrieve the saved path that you want to store in your DB then you can do

File file = future.get();
String path = file.getAbsolutePath();

you can also do this in just one line returning a path string like this

String path = Glide.with(getApplicationContext()).downloadOnly().load("your_image_url").submit().get().getAbsolutePath();

回答3:

You must call this method on the main thread

Wherever you call a method to use Glide or doing something from background, run inside:

runOnUiThread(new Runnable() {
                @Override
                public void run() {

              // Here, use glide or do your things on UiThread

            }
        });

To use it inside the main thread and then error should be gone.

回答4:

The into(ImageView) method of Glide requires you to call it only on main thread, but when you pass the loading to a Timer it will be executed in a background thread.

What you can do is to retrieve a bitmap by calling get() instead of into() and then set that bitmap on the ImageView by calling setImageBitmap().

Glide.with(getApplicationContext())
     .load("your url")
     .asBitmap()
     .get()

or

Glide.with(getApplicationContext())
     .load("your url")
     .asBitmap()
     .into(new BitmapImageViewTarget(imgView) {
      @Override
      protected void setResource(Bitmap resource) {
       //Play with bitmap
        super.setResource(resource);
      }
    });

Try this.

回答5:

Did I get the question right?

private class update extends AsyncTask<Void, Void, Void> {

    @Override
    protected void onPreExecute() {
        super.onPreExecute();
    }

    @Override
    protected Void doInBackground(Void... params) {
        try {
        RequestOptions options = new RequestOptions()
        .diskCacheStrategy(DiskCacheStrategy.ALL) // Saves all image resolution
        .centerCrop()
        .priority(Priority.HIGH)
        .placeholder(R.drawable.null_image_profile)
        .error(R.drawable.null_image_profile);

    Glide.with(context).load(imageUrl)
        .apply(options);

        } catch (Exception e) {
            e.printStackTrace();
        }
        return null;
    }

    @Override
    protected void onPostExecute(Void aVoid) {
        //finish
    }
}

来源：https://stackoverflow.com/questions/52464658/glide-cache-image-on-disk-on-background-thread