Re: How to read HTTP chunk-size from servlet?

From:

Lew <lew@nowhere.com>

Newsgroups:

comp.lang.java.programmer

Date:

Fri, 19 Jan 2007 14:29:43 -0500

Message-ID:

<RIqdnRSTZLe1gSzYnZ2dnUVZ_qCmnZ2d@comcast.com>

Rogan Dawes wrote:

If you are trying to limit the size of the body you will accept, simply
keep a tally of how many bytes you have read, and bail if you read too
many.

In case you are not familiar with the idiom, something like this will
probably work for you:

InputStream is = request.getInputStream();
ByteArrayOutputStream baos = new ByteArrayOutputStream();
byte[] buff = new byte[2048];
while ((int got=is.read(buff))>0) {
    baos.write(buff,0,got);
    if (baos.size()>MAX)
       throw new Exception("Too big");
}
byte[] requestBody = baos.toByteArray();

Or, to prevent going over before you get there, put the test before the write().

  for ( int got; (got = is.read(buff)) > 0; )
  {
      if ( (baos.size() + got) > MAX )
         throw new Exception("Too big");
      baos.write(buff,0,got);
  }

Works out about the same if the first version of MAX is buff.length larger
than the second. (My use of the 'for' idiom vs. the 'while' idiom is not
relevant, just my own style. I thought folks might benefit from seeing both
forms.)

- Lew