Re: gunzipping an URL

From:
Daniel Pitts <newsgroup.spamfilter@virtualinfinity.net>
Newsgroups:
comp.lang.java.programmer
Date:
Wed, 14 Oct 2009 10:01:40 -0700
Message-ID:
<TunBm.7809$Ku5.7008@newsfe04.iad>
LC's No-Spam Newsreading account wrote:

I have an applet which reads some astronomical images via a class of its
own. This class uses at present two constructors:

 - one constructor (used for tests) receives as argument a String file
   name and does

   DataInputStream in = new DataInputStream
                            (new BufferedInputStream(
                                 new FileInputStream(file)
                                 , 2880
                            )
                        );

 - the other constructor (used in real life) receives as argument
   an URL url and then

   URLConnection urlc = url.openConnection() ;
   urlc.connect();
   DataInputStream in = new DataInputStream
                            (new BufferedInputStream(
                                 urlc.getInputStream()
                                 , 2880
                            )
                        );

  The URL correspond to a binary file of the same kind as for a local
  file. The 2880-byte record length is intrinsic to that kind of file.

  Now I'd want to replace such files (name) with gzipped files (name.gz)

  I see that there is a class GZIPInputStream. What is the correct way
  to use it ? should I wrap it around the innermost stream ?

   DataInputStream in = new DataInputStream
                            (new BufferedInputStream(
                                 new GZIPInputStream(
                                     urlc.getInputStream()
                                     )
                                 , 2880
                            )
                        );

  Is it correct to expect that this will receive the gzipped data
  (transferred as such between apache httpd server and applet) and
  do the gunzipping locally within the applet ?

That would work, although you need to keep references to the inner-most
input stream so that you can close it in a "finally" block.

--
Daniel Pitts' Tech Blog: <http://virtualinfinity.net/wordpress/>

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