I'm trying to upload a file to Amazon's S3 using a pre-signed URL. I get the URL from a server which generates the URL & sends it to me as part of a JSON object. I get the URL as a String, something like this:
https://com-example-mysite.s3-us-east-1.amazonaws.com/userFolder/ImageName?X-Amz-Security-Token=xxfooxx%2F%2F%2F%2F%2F%2F%2F%2F%2F%2Fxxbarxx%3D&X-Amz-Algorithm=xxAlgoxx&X-Amz-Date=20170831T090152Z&X-Amz-SignedHeaders=host&X-Amz-Expires=3600&X-Amz-Credential=xxcredxx&X-Amz-Signature=xxsignxx
Unfortunately, when I pass this to Retrofit2, it modifies the String attempting to make it into a URL. I've set encoding=true
which took care of most of the problem but not completely. I know the String works as it is. I've tried it in Postman & get a successful response.
1st I tried just putting the String (except for what I cut out as baseUrl) as a whole into the Path
public interface UpdateImageInterface {
@PUT("{url}")
Call<Void> updateImage(@Path(value="url", encoded=true) String url, Body RequestBody image);
}
The calling code:
Retrofit retrofit = new Retrofit.Builder()
.baseUrl("https://com-example-mysite.s3-us-east-1.amazonaws.com/userFolder/")
.build();
UpdateImageInterface imageInterface = retrofit.create(UpdateImageInterface.class);
// imageUrl is "ImageName..."
Call<Void> call = imageInterface.updateImage(imageUrl, requestFile);
This works mostly except the the '?' (after "ImageName") get converted to "%3F". This causes a Bad Request / 400.
My next attempt was to create a query with Retrofit2 but then dump the whole String (with multiple queries) into the query.
public interface UpdateImageInterface {
@PUT("ImageName")
Call<Void> updateProfilePhoto(@Query(value="X-Amz-Security-Token", encoded = true) String token, @Body RequestBody image);
}
The calling code:
Retrofit retrofit = new Retrofit.Builder()
.baseUrl("https://com-example-mysite.s3-us-east-1.amazonaws.com/userFolder/")
.build();
UpdateImageInterface imageInterface = retrofit.create(UpdateImageInterface.class);
// imageUrl is "xxfooxx..."
Call<Void> call = imageInterface.updateImage(imageUrl, requestFile);
This gets the '?' rendered correctly but all of the '&' get changed to "%26"
Lastly I tried passing the whole String in baseUrl()
but that gives an IllegalArgumentException for not having '/' on the end.
I know that I could parse the pre-signed URL to make multiple queries & assemble them in Retrofit2 as queries should be done but I'd like to avoid that processing.
To restate the question:
Is there a way to easily (without heavy String parsing) upload a file to S3 with a pre-signed URL using Retrofit2?
A user who does not have AWS credentials or permission to access an S3 object can be granted temporary access by using a presigned URL. A presigned URL is generated by an AWS user who has access to the object. The generated URL is then given to the unauthorized user.
Sign in to the AWS Management Console and open the Amazon S3 console at https://console.aws.amazon.com/s3/ . In the Buckets list, choose the name of the bucket that contains the object that you want a presigned URL for. In the Objects list, select the object that you want to create a presigned URL for.
A presigned URL is a URL that you can provide to your users to grant temporary access to a specific S3 object. Using the URL, a user can either READ the object or WRITE an Object (or update an existing object). The URL contains specific parameters which are set by your application.
With help from a colleague, this is the solution.
public interface UpdateImageInterface {
@PUT
Call<Void> updateImage(@Url String url, @Body RequestBody image);
}
Calling code:
String CONTENT_IMAGE = "image/jpeg";
File file = new File(localPhotoPath); // create new file on device
RequestBody requestFile = RequestBody.create(MediaType.parse(CONTENT_IMAGE), file);
/* since the pre-signed URL from S3 contains a host, this dummy URL will
* be replaced completely by the pre-signed URL. (I'm using baseURl(String) here
* but see baseUrl(okhttp3.HttpUrl) in Javadoc for how base URLs are handled
*/
Retrofit retrofit = new Retrofit.Builder()
.baseUrl("http://www.dummy.com/")
.build();
UpdateImageInterface imageInterface = retrofit.create(UpdateImageInterface.class);
// imageUrl is the String as received from AWS S3
Call<Void> call = imageInterface.updateImage(imageUrl, requestFile);
Javadoc for info on @Url
(class Url) &
baseUrl()
(class Retrofit.Builder)
MediaType
is a class in the OkHttp library that is often used with Retrofit (both from Square). Info about constants passed to the parse method can be found in the Javadoc.
Use the following while uploading directly to S3 using presigned URL.
@Multipart
@PUT
@Headers("x-amz-acl:public-read")
Call<Void> uploadFile(@Url String url, @Header("Content-Type") String contentType, @Part MultipartBody.Part part);
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