Re: io - subStream or subReader class?

From:

Tom Anderson <twic@urchin.earth.li>

Newsgroups:

comp.lang.java.programmer

Date:

Tue, 27 Jul 2010 20:32:59 +0100

Message-ID:

<alpine.DEB.1.10.1007272029120.23622@urchin.earth.li>

On Tue, 27 Jul 2010, bugbear wrote:

I've looked in the standard libraries, and Apache.

I want a Reader (or Stream) that provides a view onto PART of an
existing Reader (or Stream) defined by an offset and a size.

Such an implementation would be very useful to me, e.g. for decoding
some JPEG data (using a standard JPEG stream decoder) where the JPEG is
actually held as a sub-set of some other file (e.g. the thumbnail for a
giant TIFF image).

Does anyone know of such a class/library?

If i've understood you correctly, then i think this may be of use to you:

http://commons.apache.org/fileupload/apidocs/org/apache/commons/fileupload/util/LimitedInputStream.html

This is a moderately common thing to need, and since it's not in the
standard library, there are dozens of other implementations of it around,
mostly with the same name!

It's also not hard to write if you don't want to drag in another library.
You just write a FilterInputStream with a count of bytes remaining, and
implement read() and read(byte[], int, int) to check the count and behave
accordingly. And override the mark/reset methods to respect the count, or
do nothing.

tom

--
Caps lock is like cruise control for cool.