JarURLConnection.getJarFile() resource leak when file is not found

[Peter Levart]

On 08/17/2015 04:02 PM, Neon Ngo wrote:
> The test program below shows a resource leak in java.net.JarURLConnection's getJarFile() when given an non-existent file to lookup in the jar file.
>
> Under Windows, the last printout shows that it is not able to remove the test input jar file.
> Any input jar file can be used to test this as long as it does not contain "/testNonExistentFile.xyz" in the jar file.
>
> Warning, this test program will try to delete the input file, so use with a "temporary" copy of an existing jar file.
>
> This happens under all current Oracle and OpenJDK Java versions: 6, 7, and 8 (I have not tried beta versions of 9).
> I could not find a matching BUG for this issue on both the Oracle and OpenJDK websites.
> So would like to start the conversation here since my submission on the Oracle website almost a month ago seems to have been lost.
>
> Anyone know of a workaround for this issue?

Hi Neon,

Have you tried closing the JarURLConnection before trying to delete the 
jar file?

Regards, Peter

> Regards,
>
> Neon
> === test.java ===
> package nxm.test.lib;
>
> import java.io.File;
> import java.net.JarURLConnection;
> import java.net.URL;
> import java.net.URLConnection;
> import java.util.jar.JarFile;
>
> public class test {
>
>    public static void getJarFile(String urlstr) throws Exception {
>      System.out.println("testing URL: " + urlstr);
>      URL url = new URL(urlstr);
>      URLConnection urlConnection = url.openConnection();
>      if (urlConnection instanceof JarURLConnection) {
>        JarURLConnection jarUrlConnection = (JarURLConnection) urlConnection;
>        JarFile jarFile = jarUrlConnection.getJarFile();
>        System.out.println(" Got JarFile  : " + jarFile);
>        System.out.println(" JarFile.name : " + ((jarFile != null) ? jarFile.getName() : ""));
>        jarFile.close();
>        System.out.println(" Closed JarFile " + jarFile);
>
>      } else if (urlConnection != null) {
>        System.err.println(" URLConnection.class: " + urlConnection.getClass());
>      }
>    }
>
>    public static void main(String[] args) {
>      if (args.length < 1) {
>        error("Usage: <file.jar>");
>      }
>      String jarFilename = args[0];
>      File file = new File(jarFilename);
>      if (!file.exists()) {
>        error("input jar file does not exists: " + file);
>      }
>
>      String nonExistentFileInJar = "jar:file:" + jarFilename + "!/testNonExistentFile.xyz";
>      try {
>        getJarFile(nonExistentFileInJar);
>      } catch (Exception e) {
>        e.printStackTrace();
>      }
>
>      boolean result = file.delete();
>      System.out.println("Able to remove test jar file? " + result);
>
>      if (!result) {
>        error("Unable to remove test jar file: " + jarFilename);
>      }
>    }
>
>    static void error(String msg) {
>      System.err.println(msg);
>      System.exit(1);
>    }
> }
> === end test.java ===

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