如何在Flex中将文件转换为ByteArray？

I was wondering how to convert a file I have on my server (pdf/excel/ppt) to a ByteArray. The reason I want to do this is to display the dialogue open/save as to the user and I must set the Content-Type to octet-stream. The dialogue shows fine with just navigateToURL() but for pdf's it is the user's local browser setting. For a URLRequest I must set the data as a ByteArray. I'm trying to use the code located here:I was wondering how to convert a file I have on