It appears to me that JAR file indexing breaks the mechanics of ClassLoader.getResources(). Consider the following program:
import java.io.*;
import java.net.*;
import java.util.*;
public class TryIt {
public static void main(String[] args) throws Exception {
URL[] urls = {
(new File("a.jar")).getAbsoluteFile().toURI().toURL(),
(new File("b.jar")).getAbsoluteFile().toURI().toURL()
};
URLClassLoader cl = URLClassLoader.newInstance(urls);
String[] res = { "foo", "foo/", "foo/arb", "foo/bar", "foo/cab" };
for (String r: res) {
System.out.println("'" + r + "':");
for (URL u: Collections.list(cl.getResources(r)))
System.out.println(" " + u);
}
}
}
Now prepare the JAR files mentioned in that program:
mkdir a/foo b/foo
touch a/foo/arb a/foo/bar b/foo/bar b/foo/cab
echo "Class-Path: b.jar" > mf
jar cfm a.jar mf -C a foo
jar cf b.jar -C b foo
If you run java TryIt, you will get output like this:
'foo':
jar:file:…/a.jar!/foo
jar:file:…/b.jar!/foo
'foo/':
jar:file:…/a.jar!/foo/
jar:file:…/b.jar!/foo/
'foo/arb':
jar:file:…/a.jar!/foo/arb
'foo/bar':
jar:file:…/a.jar!/foo/bar
jar:file:…/b.jar!/foo/bar
'foo/cab':
jar:file:…/b.jar!/foo/cab
But if you run jar -i a.jar to create an index, then the same command as above prints this:
'foo':
jar:file:…/a.jar!/foo
'foo/':
jar:file:…/a.jar!/foo/
'foo/arb':
jar:file:…/a.jar!/foo/arb
'foo/bar':
jar:file:…/a.jar!/foo/bar
'foo/cab':
jar:file:…/b.jar!/foo/cab
The index itself looks like this:
JarIndex-Version: 1.0
a.jar
foo
b.jar
foo
Doesn't the contract of getResources imply that all available resources matching the given name should be returned?
Finds all the resources with the given name.
Doesn't the JAR File Specification allow indexed packages to span multiple JAR files?
Normally one package name is mapped to one jar file, but if a particular package spans more than one jar file, then the mapped value of this package will be a list of jar files.
Is there some specification somewhere which says that what I'm observing is indeed correct (or at least permissible) behavior?
Is there some workaround to get all named resources despite the index?
