Making ImageGallery of private Images in S3 Client android

问题

I am trying to create an imageGallery of my S3 Bucket in my android application. My images are private so i won't be having any specific link for each image.

For Such private images , amazon has a link generator,

s3Client.generatePresignedUrl(Constants.S3_BUCKET_NAME, key, expiration);

It generates a URL with let's say 1 hour or 2 min expiration set by us.

Now for easy memory caching and stuff, i can either use volley or Picasso or many other such easy loading libraries.

However there is this catch. I want to cache these images in memory. But all i have is dynamic link.

How can i make Picasso or any other library use dynamic link to cache?

As per my information, the libraries use Url as "key" to cache, is that correcT? if so how can i save these images so i can use these images later even when i am offline, again, i have dynamic link so url will be changing every instant so maybe i need to save them with the Key i am passing to s3Client.

What is the solution.

回答1:

Latest Picasso version adopts setting network policies. Probably, you need to set NetworkPolicy.OFFLINE for the Picasso.Request builder:

Picasso.with(this)
            .load(s3Url)
            .networkPolicy(NetworkPolicy.OFFLINE)
            .into(imageView);

Regarding the caching, you might want to set expiration time to CacheControl of the Picasso OkHttpClient, to be same as the S3 links.

来源：https://stackoverflow.com/questions/31173424/making-imagegallery-of-private-images-in-s3-client-android