(Android™) AWS S3 File Streaming Upload

Demonstrates how to do a streaming upload from a file to the AWS S3 storage service. The AWS authorization presents some difficulties when the REST request body is to be streamed from a file (or from some other source). The issue is that the SHA-256 hash of the file data must be calculated. There are only two possible ways to do this: (1) stream the file into memory in its entirety and calculate the SHA-256 hash prior to uploading, or (2) pre-calculate the SHA-256 in a streaming fashion, and then provide it to the AWS authentication object.

If the application does NOT pre-compute the SHA-256, then Chilkat (internally) is forced to stream into memory, calculate the SHA-256, and then upload from the in-memory copy of the file.

Chilkat Android™ Downloads Android™ Java Libraries Android C/C++ Libraries

// Important: Don't forget to include the call to System.loadLibrary
// as shown at the bottom of this code sample.
package com.test;

import android.app.Activity;
import com.chilkatsoft.*;

import android.widget.TextView;
import android.os.Bundle;

public class SimpleActivity extends Activity {

  private static final String TAG = "Chilkat";

  // Called when the activity is first created.
  @Override
  public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    // This example requires the Chilkat API to have been previously unlocked.
    // See Global Unlock Sample for sample code.

    // This first part is optional.  AWS authentication requires
    // the SHA-256 hash of the request body (i.e. the contents of the file
    // to be uploaded).  We can choose to pre-calculate the SHA-256 in a streaming fashion
    // and then provide it to the authenticator object.  This way, if the file is
    // extremely large, it never needs to completely reside in memory.
    CkCrypt2 crypt = new CkCrypt2();
    crypt.put_EncodingMode("hex");
    crypt.put_HashAlgorithm("sha-256");
    String fileToUploadPath = "qa_data/xml/hamlet.xml";
    String hashStr = crypt.hashFileENC(fileToUploadPath);

    CkRest rest = new CkRest();

    // Connect to the Amazon AWS REST server.
    boolean bTls = true;
    int port = 443;
    boolean bAutoReconnect = true;
    boolean success = rest.Connect("s3.amazonaws.com",port,bTls,bAutoReconnect);

    // ----------------------------------------------------------------------------
    // Important: For buckets created in regions outside us-east-1,
    // there are three important changes that need to be made.
    // See Working with S3 Buckets in Non-us-east-1 Regions for the details.
    // ----------------------------------------------------------------------------

    // Provide AWS credentials for the REST call.
    CkAuthAws authAws = new CkAuthAws();
    authAws.put_AccessKey("AWS_ACCESS_KEY");
    authAws.put_SecretKey("AWS_SECRET_KEY");
    authAws.put_ServiceName("s3");
    // Provide the pre-computed SHA-256 here:
    authAws.put_PrecomputedSha256(hashStr);

    success = rest.SetAuthAws(authAws);

    // Set the bucket name via the HOST header.
    // In this case, the bucket name is "chilkat100".
    rest.put_Host("chilkat100.s3.amazonaws.com");

    CkStream fileStream = new CkStream();
    fileStream.put_SourceFile(fileToUploadPath);

    // Upload to the S3 Storage service.
    // If the application provided the SHA-256 hash of the file contents (as shown above)
    // then file is streamed and never has to completely reside in memory.
    // If the application did NOT provide the SHA-256, then Chilkat will (internally) 
    // load the entire file into memory, calculate the SHA-256, and then upload.
    String responseStr = rest.fullRequestStream("PUT","/hamlet.xml",fileStream);
    if (rest.get_LastMethodSuccess() != true) {
        Log.i(TAG, rest.lastErrorText());
        return;
        }

    // When successful, the S3 Storage service will respond with a 200 response code,
    // with an XML body.  
    if (rest.get_ResponseStatusCode() == 200) {
        Log.i(TAG, responseStr);
        Log.i(TAG, "File uploaded.");
        }
    else {
        // Examine the request/response to see what happened.
        Log.i(TAG, "response status code = " + String.valueOf(rest.get_ResponseStatusCode()));
        Log.i(TAG, "response status text = " + rest.responseStatusText());
        Log.i(TAG, "response header: " + rest.responseHeader());
        Log.i(TAG, "response body: " + responseStr);
        Log.i(TAG, "---");
        Log.i(TAG, "LastRequestStartLine: " + rest.lastRequestStartLine());
        Log.i(TAG, "LastRequestHeader: " + rest.lastRequestHeader());
        }


  }

  static {
      System.loadLibrary("chilkat");

      // Note: If the incorrect library name is passed to System.loadLibrary,
      // then you will see the following error message at application startup:
      //"The application <your-application-name> has stopped unexpectedly. Please try again."
  }
}