Get InputStream from Apache's POI Workbook

Question

Is there a way to obtain InputStream of Apache's POI Workbook?

I need it for piping to another OutputStream, however I'm unable to find such method (If it exists).

If it doesn't, any tips on alternative ways to obtain it?

Answer 1

Here's how to implement #2 of Alexander Tokarev's answer (i.e get Inputstream from a workbook):

    try {
        ByteArrayOutputStream bos = new ByteArrayOutputStream();
        workbook.write(bos);
        byte[] barray = bos.toByteArray();
        InputStream is = new ByteArrayInputStream(barray);
    } catch (IOException e) {
        e.printStackTrace();
    }

Answer 2

There's a several ways to solve this:

1. You can use standard java PipetInputStream and PipedOutputStream. But you have to create different thread for using PipedInputStream (as described in http://docs.oracle.com/javase/7/docs/api/java/io/PipedInputStream.html)
2. You can write the content to ByteArrayOutputStream, and then you can use resulting byte array via ByteArrayInputStream. This can be done sequentially in one thread.