Flex ByteArray to Java ByteArray

While trying to import XLS files from Flex front-end, we needed to pass the file contents to Java middle tier, where Apache POI library was used to parse the contents.
The Java method expects a Java ByteArray containing the file contents, but when we pass a Flex ByteArray to it, it throws error.
To overcome this instead of passing Flex ByteArray, we should pass an Array of bytes, as depicted in following code snippet:

public static function byteArrayToArrayOfBytes(ba:ByteArray):Array
{
    var arrayOfBytes:Array = [];
    ba.position = 0;
    while(ba.bytesAvailable > 0)
        arrayOfBytes.push(ba.readByte());
    ba.position = 0;
    return arrayOfBytes;
}

public function onFileSelectionComplete(fileReference:FileReference)
{
    var payload:Object = new Object();
    payload.byteArray = byteArrayToArrayOfBytes(fileReference.data);

    ExternalInterface.call("parseXLS", payload);
}