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