I'm still hoping for a better solution than this, but seeing as @aKzenT has confirmed my conclusion that there is not an existing solution for this I wrote one. Its just a simple subclass of AmazonS3Client. I worry it's brittle because I had to copy a lot of code from the method I overrode, but it seems like the most minimal solution. I can confirm that it works fine in my own code base. I posted the code in a gist, but for the sake of a complete answer:
import com.amazonaws.AmazonWebServiceRequest;
import com.amazonaws.HttpMethod;
import com.amazonaws.Request;
import com.amazonaws.auth.AWSCredentials;
import com.amazonaws.handlers.RequestHandler;
import com.amazonaws.services.s3.AmazonS3Client;
import com.amazonaws.services.s3.Headers;
import com.amazonaws.services.s3.internal.S3QueryStringSigner;
import com.amazonaws.services.s3.internal.ServiceUtils;
import java.util.Date;
/**
* This class should be a drop in replacement for AmazonS3Client as long as you use the single credential
* constructor. It could probably be modified to add additional constructors if needed, but this is the one we use.
* Supporting all of them didn't seem trivial because of some dependencies in the original presignRequest method.
*
* The only real purpose of this class is to change the behavior of generating presigned URLs. The original version
* escaped slashes in the key and this one does not. Pretty url paths are kept intact.
*
* @author Russell Leggett
*/
public class PrettyUrlS3Client extends AmazonS3Client{
private AWSCredentials awsCredentials;
/**
* This constructor is the only one provided because it is only one I needed, and it
* retains awsCredentials which might be needed in the presignRequest method
*
* @param awsCredentials
*/
public PrettyUrlS3Client(AWSCredentials awsCredentials) {
super(awsCredentials);
this.awsCredentials = awsCredentials;
}
/**
* WARNING: This method is an override of the AmazonS3Client presignRequest
* and copies most of the code. Should be careful of updates to the original.
*
* @param request
* @param methodName
* @param bucketName
* @param key
* @param expiration
* @param subResource
* @param <T>
*/
@Override
protected <T> void presignRequest(Request<T> request, HttpMethod methodName, String bucketName, String key, Date expiration, String subResource) {
// Run any additional request handlers if present
if (requestHandlers != null) {
for (RequestHandler requestHandler : requestHandlers) {
requestHandler.beforeRequest(request);
}
}
String resourcePath = "/" +
((bucketName != null) ? bucketName + "/" : "") +
((key != null) ? keyToEscapedPath(key)/* CHANGED: this is the primary change */ : "") +
((subResource != null) ? "?" + subResource : "");
//the request apparently needs the resource path without a starting '/'
request.setResourcePath(resourcePath.substring(1));//CHANGED: needed to match the signature with the URL generated from the request
AWSCredentials credentials = awsCredentials;
AmazonWebServiceRequest originalRequest = request.getOriginalRequest();
if (originalRequest != null && originalRequest.getRequestCredentials() != null) {
credentials = originalRequest.getRequestCredentials();
}
new S3QueryStringSigner<T>(methodName.toString(), resourcePath, expiration).sign(request, credentials);
// The Amazon S3 DevPay token header is a special exception and can be safely moved
// from the request's headers into the query string to ensure that it travels along
// with the pre-signed URL when it's sent back to Amazon S3.
if (request.getHeaders().containsKey(Headers.SECURITY_TOKEN)) {
String value = request.getHeaders().get(Headers.SECURITY_TOKEN);
request.addParameter(Headers.SECURITY_TOKEN, value);
request.getHeaders().remove(Headers.SECURITY_TOKEN);
}
}
/**
* A simple utility method which url escapes an S3 key, but leaves the
* slashes (/) unescaped so they can stay part of the url.
* @param key
* @return
*/
public static String keyToEscapedPath(String key){
String[] keyParts = key.split("/");
StringBuilder result = new StringBuilder();
for(String part : keyParts){
if(result.length()>0){
result.append("/");
}
result.append(ServiceUtils.urlEncode(part));
}
return result.toString().replaceAll("%7E","~");
}
}
UPDATE I updated the gist and this code to fix an issue I was having with ~'s. It was occurring even using the standard client, but unescaping the ~ fixed it. See gist for more details/track any further changes I might make.
