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From: Peter Donald <donaldp@apache.org>
To: "Avalon Development" <avalon-dev@jakarta.apache.org>
Subject: Re: [PATCH] IOUtil.java additions
Date: Thu, 5 Jul 2001 15:04:59 +1000
References: <20010704204119.C1181@socialchange.net.au>
In-Reply-To: <20010704204119.C1181@socialchange.net.au>
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Message-Id: <01070515035606.00812@helm.realityforge.org>
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On Thu,  5 Jul 2001 10:41, jeff wrote:
> In a dark corner of Excalibur lies a rather unexciting class called
> IOUtils.java. It lets you copy between InputStreams and OutputStreams,
> cleanly shut down streams, and that's it.
>
> Over the last week I have ruthlessly expanded it's functionality, such
> that there are now methods to copy from (InputStream|Reader|String) to
> (OutputStream|Writer|String), with variants to select the buffer size
> and (where appropriate) the byte->char encoding.

kewl ;)

> Example uses:
>
> // Read text from a file to a String
> String s = IOUtil.toString( new FileReader("foo.txt") );
>
> // Copy the jakarta home page to a File:
> IOUtil.copy(
>     new URL("http://jakarta.apache.org").openStream(),
>     new FileOutputStream("index.html")
>     ).close();

excellent. The only one thing I don't like is return the OutputStream/Writer 
at the end. I like the following approach better

final InputStream input = new URL("http://jakarta.apache.org").openStream();
final FileOutputStream output = new FileOutputStream("index.html");
try { IOUtil.copy( input, output ); }
finally
{
  IOUtil.shutdownStream( input );
  IOUtil.shutdownStream( output );
}

because it forces users to deal with exceptions. Otherwise you get cases like

IOUtil.copy(
     new URL("http://jakarta.apache.org").openStream(),
     new FileOutputStream("index.html")
     ).close()

When this raises an exception the output stream is never shutdown and you can 
quickly foobar the system. I actually had a security leak caused by this once 
(my authenticator would stop authenticating after ~256 requests as it would 
hit FD limit for process). SO it is possible I am just particularly sensitive 
on this issue ;)

Thoughts?

BTW instead of diffing against /dev/null it would be better to just send file 
so CVS weenies like myself don't end up scratching their heads ;)

Cheers,

Pete

*-----------------------------------------------------*
| "Faced with the choice between changing one's mind, |
| and proving that there is no need to do so - almost |
| everyone gets busy on the proof."                   |
|              - John Kenneth Galbraith               |
*-----------------------------------------------------*

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