[jira] [Commented] (LOG4J2-3047) Don't assume that jar:-URL yield JarURLConnections

["Jesse Glick (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/LOG4J2-3047?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17714305#comment-17714305 ] 

Jesse Glick commented on LOG4J2-3047:
-------------------------------------

I think this can now be resolved (2.20.0)?

> Don't assume that jar:-URL yield JarURLConnections
> --------------------------------------------------
>
>                 Key: LOG4J2-3047
>                 URL: https://issues.apache.org/jira/browse/LOG4J2-3047
>             Project: Log4j 2
>          Issue Type: Improvement
>          Components: Configuration
>    Affects Versions: 2.13.1
>            Reporter: Andreas Sewe
>            Priority: Major
>          Time Spent: 10m
>  Remaining Estimate: 0h
>
> Hi, I am currently investigating a bug in an *IntelliJ* plug-in which uses Log4J2 internally for its logging needs and the uses an {{Appender}} to reroute log messages to IntelliJ's debug log. This approach works fine.
> Unfortunately, with IntelliJ 2021.1, its developers have decided to swap the default {{JarURLConnection}} for their own implementation, [for "performance reasons"|https://youtrack.jetbrains.com/issue/IDEA-264777#focus=Comments-27-4777159.0-0], as they claim. This leads to the unfortunate situation that a straight-forward {{jar:[file:/some/file.jar!some/package|file:///some/file.jar!some/package]}} URL no longer yields a {{JarURLConnection}} but merely a plain {{URLConnection}}.
> Now I am not 100%-sure whether the rule "{{jar:}}-URL yields {{JarURLConnection}}" is part of the Java API; AFAICT, that is only stipulated in a code example in the Javadoc of {{JarURLConnection}}, not on {{URL}} or {{URLConnection}} themselves:
> {code:java}
>  * <p>Users should cast the generic URLConnection to a
>  * JarURLConnection when they know that the URL they created is a JAR
>  * URL, and they need JAR-specific functionality. For example:
>  *
>  * <pre>
>  * URL url = new URL("jar:file:/home/duke/duke.jar!/");
>  * JarURLConnection jarConnection = (JarURLConnection)url.openConnection();
>  * Manifest manifest = jarConnection.getManifest();
>  * </pre>
> {code}
> But regardless of who is to blame, I think Log4J's {{ResolverUtil}} can safely drop that assumption:
> In {{ResolverUtil.findInPackage}}, {{extractPath}} has already extracted the path to the JAR file in question, so the call to {{loadImplementationsInJar(Test, String, URL}} could IMHO safely be replaced by {{loadImplementationsInJar(Test, String, File)}}, thereby
>  # removing one of the {{else if}} cases in {{findInPackage}}
>  # removing the only use of {{loadImplementationsInJar(Test, String, URL)}}
>  # getting rid of the "{{jar:}}-URL yield {{JarURLConnection}}" assumption, which is at least somewhat contested/implicit in the Java API.



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