How to build/read attachment part using JavaMail in GAE

Attachment.java

class Attachment {
	public byte[] data;
	public String fileName;
	public String contentType;

	public Attachment(String fileName, byte[] data, String contentType) {
		this.data = data;
		this.fileName = fileName;
		int id = contentType.indexOf(";");
		this.contentType = id > -1 ? contentType.substring(0, id) : contentType;;
	}

	public int getFileSize() {
		return data == null ? -1 : data.length;
	}
}

gae_mail_attachment.java

byte[] attachmentData = ...;
String attachmentContentType = ...;
String attachmentFileName = ...;

MimeBodyPart attachmentPart = new MimeBodyPart();
attachmentPart.setFileName(attachmentFileName);
attachmentPart.setDisposition(Part.ATTACHMENT);
DataSource src = new ByteArrayDataSource(attachmentData, attachmentContentType);
DataHandler handler = new DataHandler(src);
attachmentPart.setDataHandler(handler);

getAttachment.java

private Attachment getAttachment(BodyPart bodyPart) throws Exception {
	String disposition = bodyPart.getDisposition();
	if (disposition != null && (disposition.equals(Part.ATTACHMENT) || (disposition
					.equals(Part.INLINE)))) {
		InputStream attachmentInputStream = null;
		try {
			attachmentInputStream = bodyPart.getInputStream();
			byte[] data = getBytesFromInputStream(attachmentInputStream);
			return new Attachment(bodyPart.getFileName(), data, bodyPart.getContentType());
		} finally {
			try {
				if (attachmentInputStream != null)
					attachmentInputStream.close();
			} catch (Exception e) {
			}
		}
	}
	return null;
}

getBytesFromInputStream.java

public byte[] getBytesFromInputStream(InputStream inputStream) throws IOException {
	BufferedInputStream bis = null;
	ByteArrayOutputStream bos = null;
	try {
		bis = new BufferedInputStream(inputStream);
		// write it to a byte[] using a buffer since we don't know the exact
		// image size
		byte[] buffer = new byte[1024];
		bos = new ByteArrayOutputStream();
		int i = 0;
		while (-1 != (i = bis.read(buffer))) {
			bos.write(buffer, 0, i);
		}
		byte[] data = bos.toByteArray();
		return data;
	} catch (IOException e) {
		throw e;
	} finally {
		try {
			if (bis != null)
				bis.close();
			if (bos != null)
				bos.close();
		} catch (IOException e) {
			// ignore
		}
	}
}