RFR - 8132734: java.util.jar.* changes to support multi-release jar files

[Steve Drach]

> On Jan 30, 2016, at 12:00 AM, Alan Bateman <Alan.Bateman at oracle.com> wrote:
> 
> 
> On 29/01/2016 17:39, Paul Sandoz wrote:
>> :
>> Alan’s point is that traversing using entries()/stream() always returns the versioned entries (if any) rather than all entries, thus in a sense filters.
>> 
>> My assumption was the traversal should by default be consistent with a calls to getEntry, thus:
>> 
>>  jarFile.stream().forEach(e -> {
>>     JarEntry je = jarFile.getJarEntry(e.getName());
>>     assert e.equals(je);
>>  });
>> 
>> There might need to be another stream method that returns all entries.
>> 
> Right, I'm mostly just wondering if entries()/streams() should override the entries in the stream with versioned entries and filter out the META-INF/versions/ tree.

I don’t think so.  That kind of behavior might be difficult to understand.  Returning all the entries provides some flexibility.  One can write code like this:

jarfile.stream().map(JarEntry::getName).filter(s -> !s.startsWith(“META-INF”)).map(JarFile::getJarEntry).etc

to get the versioned results for any version you specify when constructing the JarFile.

> 
> If I've gone to trouble of specifying the a Release then it seems the right thing to do. On the other hand, it comes at a cost and there will be use-cases like "get the names of all entries" that would be more efficient to just build on the current entries()/stream(). I'm loath to suggest this might need a new method but it might be one of the options to consider here. Minimally there is a javadoc to specify on how these methods behave when the JAR is multi-release and opened by specifying a release.

How’s this?

diff -r 68867430065b src/java.base/share/classes/java/util/jar/JarFile.java
--- a/src/java.base/share/classes/java/util/jar/JarFile.java	Fri Jan 29 12:34:44 2016 -0800
+++ b/src/java.base/share/classes/java/util/jar/JarFile.java	Mon Feb 01 09:48:05 2016 -0800
@@ -576,9 +576,11 @@
     }
 
     /**
-     * Returns an enumeration of the jar file entries.
+     * Returns an enumeration of all the jar file entries.  Constructing this
+     * JarFile with the {@link JarFile#JarFile(File, boolean, int, Release)}
+     * constructor does not modify the behavior of this method.
      *
-     * @return an enumeration of the jar file entries
+     * @return an enumeration of the all jar file entries
      * @throws IllegalStateException
      *         may be thrown if the jar file has been closed
      */
@@ -587,11 +589,13 @@
     }
 
     /**
-     * Returns an ordered {@code Stream} over the jar file entries.
+     * Returns an ordered {@code Stream} over all the jar file entries.
      * Entries appear in the {@code Stream} in the order they appear in
-     * the central directory of the jar file.
+     * the central directory of the jar file.  Constructing this
+     * JarFile with the {@link JarFile#JarFile(File, boolean, int, Release)}
+     * constructor does not modify the behavior of this method.
      *
-     * @return an ordered {@code Stream} of entries in this jar file
+     * @return an ordered {@code Stream} of all entries in this jar file
      * @throws IllegalStateException if the jar file has been closed
      * @since 1.8
      */