gunzipping an URL

[Guest]

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 ?

 

[Daniel Pitts]

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.

 

[Mike Schilling]

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.

Won't closing the outermost stream close all the others?

 

[Daniel Pitts]

Won't closing the outermost stream close all the others?

Yes, but any one of those constructors may through an exception, in
which case you've lost the reference.

 

[Mike Schilling]

Yes, but any one of those constructors may through an exception, in
which case you've lost the reference.

Good point.