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From Jesse Glick <jesse.gl...@sun.com>
Subject Re: <delete> task for antlib jars
Date Fri, 20 Feb 2004 08:33:50 GMT
Mariano Benitez wrote:
> I am using antlibs, and I face the normal problem in windows of not 
> being able of deleting the file while it is used.
> 
> I know this discussion must have probably taken place, I could not 
> just find it :( Has there been any attempt to use File.deleteOnExit()
> as an option for the task? or another task?

Note that using File.deleteOnExit from a task may cause it to not work 
as expected when Ant is being run in an embedded environment such as 
from an IDE, as F.dOE takes effect at VM exit time (not necessarily when 
Ant finishes the build).

Besides running Linux :-) I am not sure what to recommend... Jose points 
out that since Ant uses a custom class loader, that loader could release 
any JARs it has open when it is instructed to. That may work, but not 
always - if you once open a jar-protocol URLConnection from a JAR (which 
is common, if any code uses ThisClass.class.getResource("something") or 
similar idioms), the Sun JRE will open that JAR in a private cache 
somewhere and never close it while the JVM is running. On Windows, this 
means that JAR cannot be deleted or modified until the JVM is stopped.

The crudest but most effective workaround on Windows is simply to not 
read from the original JAR at all. Create a new File.createTempFile, set 
it to deleteOnExit, copy the original JAR to it, and open that instead. 
You pay a modest overhead in the time spent copying (might not be much 
compared to other costs), and some temporary disk usage in C:\TEMP.

-J.

-- 
Jesse Glick <mailto:jesse.glick@sun.com> x22801
NetBeans, Open APIs  <http://www.netbeans.org/>


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