Android: Encode Image (of type File) to Base64

Question

In Java, how would I encode an Image (of type File) into base64. I'm trying to upload this image from an Android app to Imgur. Thanks!

Answer 1

Well, if you are using the Apache HTTP client for connecting to the service. I would recommend using MultiPartEntity for submitting the image. I am not sure as to exactly why, but when I tried Base64, I ran into issues when the image was huge (OOM exceptions).

To submit the image using the Apache HTTP client. All you need to do is create a MultiPartEntity and add the image using addPart.

public class UploadImagePayload extends MultiPartEntity {


public UploadImagePayload(ProgressListener listener, String imageFileUrl) {
    super(HttpMultipartMode.STRICT, listener);

    this.addPart("image", new FileBody(new File(imageFileUrl)));
    this.setStringPart("type", "file");
}

public void setAlbumId(String albumId) {
    this.setStringPart("album_id", albumId);
}

public void setName(String name) {
    this.setStringPart("name", name);
}

public void setTitle(String title) {
    this.setStringPart("title", title);
}

public void setDescription(String description) {
    this.setStringPart("description", description);
}

private void setStringPart(String name, String value) {
    try {
        addPart(name, new StringBody(value));
    } catch (UnsupportedEncodingException e) {
        e.printStackTrace();
        Log.e(TAG, "unable to set string property on image upload");
    }
}
}

Then just create an instance of the above class and set the data to it:

    myEntity.addPart("image", new FileBody(new File(imageFileUrl)));
    myEntity.setStringPart("type", "file");

To send the request, just create an HTTPPost, and set the payload to your entity:

    HttpPost post = new HttpPost(requestUrl);
    post.setEntity(myEntity);
    HttpClient client = new DefaultHttpClient();
    client.execute(post);

Using the above is fairly simple, and it is really easy to add progress listening to by just adding more logic by extending MultiPartEntiy, for example:

public class BigMultiPartEntity extends MultipartEntity {

private ProgressListener listener;

public BigMultiPartEntity(final HttpMultipartMode mode, final ProgressListener listener)
{
    super(mode);
    this.listener = listener;
}

public BigMultiPartEntity(HttpMultipartMode mode, final String boundary, final Charset charset, final ProgressListener listener)
{
    super(mode, boundary, charset);
    this.listener = listener;
}

@Override
public void writeTo(final OutputStream outstream) throws IOException
{
    super.writeTo(new CountingOutputStream(outstream, this.listener));
}

public interface ProgressListener {
    void transferred(int num);
}

public class CountingOutputStream extends FilterOutputStream
{
    private ProgressListener listener;
    private int transfered;

    /**
     * Creates an output stream filter built on top of the specified
     * underlying output stream.
     *
     * @param out the underlying output stream to be assigned to
     *            the field <tt>this.out</tt> for later use, or
     *            <code>null</code> if this instance is to be
     *            created without an underlying stream.
     */
    public CountingOutputStream(OutputStream out, ProgressListener listener) {
        super(out);
        this.listener = listener;
        this.transfered = 0;
    }

    @Override
    public void write(byte[] b, int off, int len) throws IOException {
        this.transfered += len;
        //Log.d(TAG, "writing...transfer @ "+transfered);
        this.listener.transferred((int) ((transfered / (float) getContentLength()) * 100));
        out.write(b, off, len);


    }

    @Override
    public void write(int b) throws IOException {
        this.transfered += b;
        //Log.d(TAG, "writing...transfer @ "+transfered);
        this.listener.transferred((int) ((transfered / (float) getContentLength()) * 100));
        out.write(b);
    }
}
}

If you are not using Apache HTTPClient, and you are certainly wanting to use Base64, then have a look at: How to convert a image into Base64 string?

If you need anymore help, check out the source code for my android imgur app located @ https://bitbucket.org/eggman87/ezimgur-open/src . The logic for talking to imgur is in the API project.