🐛 Allow Class Loader to Enumerate Directory Entries#1049
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ArneBab merged 1 commit intoApr 6, 2025
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JAR (ZIP) files are technically not required to have directory entries; it is absolutely fine for a JAR file to only have a META-INF/MANIFEST.MF entry, without a corresponding META-INF directory entry. If a JAR file does have separate entries for directories, though, the getResource() and getResources() methods are expected to return URLs for these entries. Our JarClassLoader did not do that. The problem occured when I was working with Flyway and its classpath scanning: it refused to locate the directory in the classpath that the migration scripts were stored in. After much debugging it was found that the name of the directory is handed in to getResources() without a trailing slash, but the JarClassLoader uses the ZipEntry.getName() method to get the name of the current entry, and that method will return a name ending with “/” if the entry is a directory. The fix is to check for a name with an appended slash as well.
ArneBab
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Apr 6, 2025
ArneBab
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That’s a good catch! 👍
Thank you for the fix!
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JAR (ZIP) files are technically not required to have directory entries; it is absolutely fine for a JAR file to only have a
META-INF/MANIFEST.MFentry, without a correspondingMETA-INFdirectory entry.If a JAR file does have separate entries for directories, though, the
getResource()andgetResources()methods are expected to return URLs for these entries. OurJarClassLoaderdid not do that.The problem occured when I was working with Flyway and its classpath scanning: it refused to locate the directory in the classpath that the migration scripts were stored in. After much debugging it was found that the name of the directory is handed in to
getResources()without a trailing slash, but theJarClassLoaderuses theZipEntry.getName()method to get the name of the current entry, and that method will return a name ending with “/” if the entry is a directory.The fix is to check for a name with an appended slash as well.