I need to know the size of an inputstream [Java]

Question

My current situation is I have to read in a file and place it in an InputStream, and then also place the contents of the InputStreaminto a byte array which requires that i know the size of the InputStream. Any ideas?

As requested, i will show the input stream that i am creating from an uploaded file

 InputStream uploadedStream = null;
  FileItemFactory factory = new DiskFileItemFactory();
  ServletFileUpload upload = new ServletFileUpload(factory);
  java.util.List items = upload.parseRequest(request);   
  java.util.Iterator iter = items.iterator();

  while (iter.hasNext()) {
      FileItem item = (FileItem) iter.next();
      if (!item.isFormField()) {
       uploadedStream = item.getInputStream();
          //CHANGE uploadedStreambyte = item.get()
      }
  }

request is a HttpServletRequest object, and FileItemFactory adn ServletFileUpload are from Apache Commons FileUpload

Answer 1

You can't determine the amount of data in a stream without reading it; you can, however, ask for the size of a file:

http://java.sun.com/javase/6/docs/api/java/io/File.html#length()

If that isn't possible, you can write the bytes you read from the input stream to a ByteArrayOutputStream which will grow as required.

Answer 2

I would read into a ByteArrayOutputStream and then call toByteArray() to get the resultant byte array. You don't need to define the size in advance (although it's possibly an optimisation if you know it. In many cases you won't)

Answer 3

I just wanted to add, Apache Commons IO has stream support utilities to perform the copy. (Btw, what do you mean by placing the file into an inputstream? Can you show us your code?)

Edit:

Okay, what do you want to do with the contents of the item? There is an item.get() which returns the entire thing in a byte array.

Edit2

item.getSize() will return the uploaded file size.