Android Picasso prefetching all images to disk

Question

I want to prefetch images using Picasso and save them all to disk upon opening the app (no lazy loading on the fly). To make sure the cache is big enough I am using the following code in my Application onCreate

ContextWrapper cw = new ContextWrapper(getApplicationContext());
// path to /data/data/yourapp/app_data/imageDir
File directory = cw.getDir("imageDir", Context.MODE_PRIVATE);

OkHttpClient client = new OkHttpClient.Builder()
        .cache(new Cache(directory, Integer.MAX_VALUE))
        .build();
OkHttp3Downloader okHttp3Downloader = new OkHttp3Downloader(client);
Picasso.Builder builder = new Picasso.Builder(this);
builder.downloader(okHttp3Downloader);
Picasso built = builder.build();
built.setIndicatorsEnabled(false);
built.setLoggingEnabled(false);
Picasso.setSingletonInstance(built);

So here I set my cache size to Integer.MAX_VALUE which should be big enough ;)

I use code similar to this line to prefetch the image: Picasso.with(context).load(url).fetch();.

Now when I kill my internet and mobile data, no images are loaded even though the my code is fetching items. Any ideas why?

in general this seems like a very bad idea to download all images on forehand. I can't imagine the amount of space you are allocating on people's precious disk space. — timr, Jun 18 '16 at 14:35
@tim I fully agree. Wasn't my descision but lazy loading wasn't an option. — Gooey, Jun 18 '16 at 14:36

score 0 · Answer 1 · edited May 23 '17 at 12:33

Maybe the problem is loosing state. Did you try to extend Application class (like this) and keep Picasso instance here?

In similar situation when I needed to fetch lots of images, I save them to internal memory (not just in some cache) - to prevent from reloading, and save uri's to files into SQLite and then use Picasso to work with such URI's. (don't forget to check that user don't delete anything).

score 0 · Accepted Answer · answered Oct 25 '16 at 11:28

0

In the end I created my own image manager that downloads and store images (still using picasso to download them).

answered Oct 25 '16 at 11:28

Gooey

4,740
10
42
76

May I ask for more information on the Image Manager? What downloader are you you using? What is your process of downloading and storing the images? Are you running an `IntentService` to do the job? I am trying to do something similar with JobScheduler but the activity is being destroyed before the job is completing and job gets cancelled. – Anshul Vyas Sep 24 '18 at 17:19

score 0 · Answer 3 · edited Jun 20 '20 at 09:12

Here is my approach:

In Application's onCreate method do:

Picasso picasso = new Picasso.Builder(this)
        .downloader(new OkHttp3Downloader(this,Integer.MAX_VALUE))
        .build();
picasso.setIndicatorsEnabled(BuildConfig.DEBUG);
picasso.setLoggingEnabled(BuildConfig.DEBUG);
Picasso.setSingletonInstance(picasso);

And then wherever you want to load your images call this for each image's url:

Picasso.with(context).load(url).fetch();

From doc:

fetch()

Asynchronously fulfills the request without a ImageView or Target. This is useful when you want to warm up the cache with an image.

You can even pass in callback to check for possible errors

Android Picasso prefetching all images to disk

3 Answers3