File I/O with rjb

I am trying to do file i/o with rails and rjb and can't figure out a way to make this work. Here's what I am trying to do: - a user uploads an image to the server via a standard html form:      <%= file_field("blog", "attach") %> - this returns a ruby File object to the controller in      params[:blog][:attach] - then I need to convert this into a Java InputStream object in order to use it as an argument to another Java method.

I have tried to accomplish this many ways by using the obvious approach ... all without success. For example, - read the contents of the file into a ruby string, then try to create a java ByteArrayInputStream directly from this. - read the contents of the file into a ruby string, create a java String from this and then try to create a java ByteArrayInputStream from the java String - and many other permutations I fear I am missing something very simple here...

Has anyone accomplished something like this? If so I would appreciate seeing a sample of actual working code.

Thanks, Martin