What is the best way to make a copy of an InputStream in java [duplicate]

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Possible Duplicate:

How to make a deep copy of an InputStream in Java ?

I have an InputStream object and I want to make a copy of it. What is the best way to do this?

The data is not coming from a file but as the payload of a http form being sent from a we开发者_高级运维b page, I am using the Apache Commons FileUpload lib, my code which gives me the InputStream looks like this: ...

InputStream imageStream = null;

boolean isMultipart = ServletFileUpload.isMultipartContent(request);
        FileItemFactory factory = new DiskFileItemFactory();
        ServletFileUpload upload = new ServletFileUpload(factory);
        List items = new ArrayList();

        items = upload.parseRequest(request);
        Iterator iter = items.iterator();
        while (iter.hasNext()) {
            FileItem item = (FileItem) iter.next();
            if (item.isFormField()) { // this is subject Id
                if (item.getFieldName().equals("subId")) {
                    subId = Integer.parseInt(item.getString());
                    System.out.println("SubId: " + subId);
                }
            } else {
                imageStream = item.getInputStream();

            }
        }

What is the best way to get a duplicate/copy of imageStream?

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If you want to be able to read the stream again, I think your best option is to wrap the InputStream in a BufferedInputStream, and then use the BufferedInputStream mark() and reset() methods. The InputStream you have will probably not support them directly, since as far as I understood it receives data from the web.

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The best way of "copying" your input stream is to use commons-io. Since you're using commons fileupload alread, that additional dependency won't hurt:

http://commons.apache.org/io/

Be aware though, that you cannot really "copy" a stream. You can only "consume" it (and then maybe store the contents in memory, if you want that)