review request for 7021582, use try-with-resources in jar/zip implementation and tests

[Stuart Marks]

Hi Sherman, all,

Here's a webrev to convert code in the jar/zip implementation files and tests 
to use the new Java 7 try-with-resources construct.

http://cr.openjdk.java.net/~smarks/reviews/7021582/webrev.0/

There are rather a lot of files, however, most of the changes are pretty 
straightforward. A typical conversion changes code like this:

     FileInputStream fis = new FileInputStream(filename);
     // use fis
     fis.close();

to this:

     try (FileInputStream fis = new FileInputStream(filename)) {
         // use fis
     }

The majority of the conversions are like the above. However, there are a 
several places where I had to rearrange things either in order to get them to 
work at all, to improve robustness, or for general cleanup.

Some of these are marked with "TODO". I will of course remove these comments 
before committing the changes. Where you see these comments, you might want to 
give the code a bit more scrutiny.

Specific examples of things to look at follow:

* test/java/util/jar/JarEntry/GetMethodsReturnClones.java

I had to change the ordering of local variable declarations so that the 
variable was visible where it's used. TWR introduces a nested block, so 
obviously a local declared within will have to be moved outside in order to be 
used outside. This occurs in several other places as well. In some cases 
initialization order was changed. This shouldn't matter, though, since it's 
things like opening a file vs. allocating an array.

* src/share/classes/com/sun/java/util/jar/pack/Driver.java

I narrowed the scope of the open resource. No sense keeping it open any longer 
than necessary. This occurs in several other places as well.

* src/share/classes/com/sun/java/util/jar/pack/PackageReader.java
* src/share/classes/com/sun/java/util/jar/pack/PackageWriter.java

These changes rely on recent changes to TWR's handling of null resources. 
Currently, TWR will avoid calling close if the resource is null. Joe checked in 
this change just last week. Before that, a null resource would generate an 
unavoidable NPE when it attempted to call close(). Handling of non-null 
resources is unchanged.

I don't think the change to null handling is in a promoted build yet. Is it OK 
to check in code that depends on it? All tests pass, but that just means that 
the path where the resource is null isn't tested.

* src/share/classes/com/sun/java/util/jar/pack/PropMap.java

Narrowed the scope of catch IOException; should be OK since the code that was 
migrated out cannot throw IOException.

* src/share/classes/com/sun/java/util/jar/pack/UnpackerImpl.java

This closes its input after successful processing. I changed this so that it 
also closes its input if an exception is thrown.

* test/java/util/zip/LargeZip.java

I've "unrolled" a cascade of constructors into separate resource variables. 
This also occurs in several other places. Basically code that used to look like 
this:

     ZipOutputStream zos = new ZipOutputStream(
         new BufferedOutputStream(
             new FileOutputStream(largeFile)));
     // process zos
     zos.close();

is converted to this:

     try (FileOutputStream fos = new FileOutputStream(largeFile);
          BufferedOutputStream bos = new BufferedOutputStream(fos);
          ZipOutputStream zos = new ZipOutputStream(bos))
     {
         // process zos
     }

I think this more robust, since it closes the FileOutputStream if an exception 
occurs during the construction of one of the stacked streams, which the 
original code did not handle. Since the wrapper streams will close their 
underlying streams, this will result in redundant close() calls. However, 
close() is supposed to be idempotent so this should be OK.

* test/java/util/zip/ZipFile/DeleteTempJar.java

I'm not sure if this properly handles an IOException caused by 
HttpExchange.close(). Funny, the method isn't declared to throw IOE, but this 
test did compile and pass.

* test/java/util/zip/ZipFile/LargeZipFile.java

I changed this to fail the test if close() were to throw IOE. I think this is 
proper for test code.

* test/java/util/zip/ZipFile/ReadZip.java

I took the liberty of converting the file copying code to use the new 
java.nio.file.Files utilities. Well, I'm really following Alan's lead here 
since he's prompted me to do so in other places a couple times already. :-)

Thanks for reviewing!

s'marks