将Java应用程序从不区分大小写的文件系统移动到区分大小写的文件系统

Question

We have been running our Java code on windows servers for years. We want to run the same code on some FreeBSD boxes but our code has grown up in an environment where file/path name are case insensitive for so long that a lot of the code will break.

What I want to do is some sort of trick where we subclass File or FileSystem or some similar trick and this forces all our file names to lower case (all the time).

It seems pretty possible (ie extend File with a new class OurFile that forces everything lower case). Then we would run a script that turns all files/folders on the OS lower case and bam, bugs squashed.

It seems like some similar hacking with a new FileSystem implementation would also yield a good result.

I then thought -- surely someone before me has faced this issue and licked it good.

So, what is the wisdom out there? Is there an easy/standard way to fix this sort of case sensitivity problem? (ie has someone written LowerCaseFileSystemForPortingWindowsToUnix extends FileSystem, and tested it etc.?)

Answer 1

Have you considered fixing your code? From your description, you seem to have a lot of file/resource references which 'case-insensitive' (so, simply speaking, incorrect) names in code... It can be done either by adapting file names to how they are referenced in code (only when there is some consequence in code, fg all file names are lower-case) or adapt the constants in code to match file names.

Any wraps to java.io classes would require to list all files/directories anywhere in path and trying to find name that would match the path. However, on U**x system you could have both resources and Resources directory etc., so which one would you take for path 'RESOURCES/IMAGES/MYIMAGE.PNG'? Additionally, you would suffer from performance issues for I/O operations.

I've once 'fixed' such project, fortunatelly it was quite small, but it was very annoying. For my luck, some operations could be scripted, for example changing all constants in single file to lower-case and lower-casing all image filenames etc.

Answer 2

If your file access methods go through a small number of classes (like new File(String filename) ) then you might be able to use AspectJ to weave in some code which modifies the case of the filename as it is passed through.

Something like:

@Around(value = "newFile(context)", argNames = "point")
public Object requiresNew(ProceedingJoinPoint point) throws Throwable {

  String filename = (String) point.getArgs()[0];
  return point.proceed(new String[] { filename.toLowerCase() });
}

This would probably be a lot less intrusive on your codebase than extending File , plus it would give you an exit strategy:

1. log.warn() all filenames passed through which are not entirely lower case
2. Fix the warnings as they arise
3. Remove the aspect once it's bedded in