How do I use disk caching in Picasso?

I am using Picasso to display image in my android app:

/**
* load image.This is within a activity so this context is activity
*/
public void loadImage (){
    Picasso picasso = Picasso.with(this); 
    picasso.setDebugging(true);
    picasso.load(quiz.getImageUrl()).into(quizImage);
}

I have enable debugging and it always shows either red and green .But never shows yellow

Now if i load same image next time and internet is not available the image is not loaded.

Questions:

1. Does it not have local disk cache?
2. How do i enable disk caching as i will be using same image multiple times.
3. Do i need to add some disk permission to android manifest file?

Solution 1:

This is what I did. Works well.

First add the OkHttp to the gradle build file of the app module:

compile 'com.squareup.picasso:picasso:2.5.2'
compile 'com.squareup.okhttp3:okhttp:3.10.0'
compile 'com.jakewharton.picasso:picasso2-okhttp3-downloader:1.1.0'

Then make a class extending Application

import android.app.Application;

import com.jakewharton.picasso.OkHttp3Downloader;
import com.squareup.picasso.Picasso;

public class Global extends Application {
    @Override
    public void onCreate() {
        super.onCreate();

        Picasso.Builder builder = new Picasso.Builder(this);
        builder.downloader(new OkHttp3Downloader(this,Integer.MAX_VALUE));
        Picasso built = builder.build();
        built.setIndicatorsEnabled(true);
        built.setLoggingEnabled(true);
        Picasso.setSingletonInstance(built);

    }
}

add it to the Manifest file as follows :

<application
        android:name=".Global"
        .. >

</application>

Now use Picasso as you normally would. No changes.

EDIT:

if you want to use cached images only. Call the library like this. I've noticed that if we don't add the networkPolicy, images won't show up in an fully offline start even if they are cached. The code below solves the problem.

Picasso.with(this)
            .load(url)
            .networkPolicy(NetworkPolicy.OFFLINE)
            .into(imageView);

EDIT #2

the problem with the above code is that if you clear cache, Picasso will keep looking for it offline in cache and fail, the following code example looks at the local cache, if not found offline, it goes online and replenishes the cache.

Picasso.with(getActivity())
.load(imageUrl)
.networkPolicy(NetworkPolicy.OFFLINE)
.into(imageView, new Callback() {
    @Override
    public void onSuccess() {

    }

    @Override
    public void onError() {
        //Try again online if cache failed
        Picasso.with(getActivity())
                .load(posts.get(position).getImageUrl())
                .error(R.drawable.header)
                .into(imageView, new Callback() {
            @Override
            public void onSuccess() {

            }

            @Override
            public void onError() {
                Log.v("Picasso","Could not fetch image");
            }
        });
    }
});

Solution 2:

1) answer of first question : according to Picasso Doc for With() method

The global default Picasso instance returned from with() is automatically initialized with defaults that are suitable to most implementations.

• LRU memory cache of 15% the available application RAM
• Disk cache of 2% storage space up to 50MB but no less than 5MB.

But Disk Cache operation for global Default Picasso is only available on API 14+

2) answer of second Question : Picasso use the HTTP client request to Disk Cache operation So you can make your own http request header has property Cache-Control with max-age And create your own Static Picasso Instance instead of default Picasso By using

1] HttpResponseCache (Note: Works only for API 13+ )
2] OkHttpClient (Works for all APIs)

Example for using OkHttpClient to create your own Static Picasso class:

• First create a new class to get your own singleton picasso object

  import android.content.Context;
  import com.squareup.picasso.Downloader;
  import com.squareup.picasso.OkHttpDownloader;
  import com.squareup.picasso.Picasso;
  
  public class PicassoCache {
  
      /**
       * Static Picasso Instance
       */
      private static Picasso picassoInstance = null;
  
      /**
       * PicassoCache Constructor
       *
       * @param context application Context
       */
      private PicassoCache (Context context) {
  
          Downloader downloader   = new OkHttpDownloader(context, Integer.MAX_VALUE);
          Picasso.Builder builder = new Picasso.Builder(context);
              builder.downloader(downloader);
  
          picassoInstance = builder.build();
      }
  
      /**
       * Get Singleton Picasso Instance
       *
       * @param context application Context
       * @return Picasso instance
       */
      public static Picasso getPicassoInstance (Context context) {
  
          if (picassoInstance == null) {
  
              new PicassoCache(context);
              return picassoInstance;
          }
  
          return picassoInstance;
      }
  
  } 
  

• use your own singleton picasso object Instead of Picasso.With()

PicassoCache.getPicassoInstance(getContext()).load(imagePath).into(imageView)

3) answer for third question : you do not need any disk permissions for disk Cache operations

References: Github issue about disk cache, two Questions has been answered by @jake-wharton -> Question1 and Question2

Solution 3:

For caching, I would use OkHttp interceptors to gain control over caching policy. Check out this sample that's included in the OkHttp library.

RewriteResponseCacheControl.java

Here's how I'd use it with Picasso -

OkHttpClient okHttpClient = new OkHttpClient();
    okHttpClient.networkInterceptors().add(new Interceptor() {
        @Override
        public Response intercept(Chain chain) throws IOException {
            Response originalResponse = chain.proceed(chain.request());
            return originalResponse.newBuilder().header("Cache-Control", "max-age=" + (60 * 60 * 24 * 365)).build();
        }
    });

    okHttpClient.setCache(new Cache(mainActivity.getCacheDir(), Integer.MAX_VALUE));
    OkHttpDownloader okHttpDownloader = new OkHttpDownloader(okHttpClient);
    Picasso picasso = new Picasso.Builder(mainActivity).downloader(okHttpDownloader).build();
    picasso.load(imageURL).into(viewHolder.image);