Java 7：了解文件是否为符号链接是否有帮助？

Question

In Java 7 it provides me a way to detect whether a file is symbolic link or not , but why anyone would want to know that .

Files.isSymbolicLink(target) //here target is a path.

I never needed that so far, just wondering what will be the use of it ?

Answer 1

Suppose you're writing a recursive directory copy - you may decide not to follow symbolic links. Or maybe you're creating an archive in a format that doesn't support symbolic links - you may want to warn the user if you encounter one. Or maybe you're writing a diff program, and you want to skip pairs of files which are actually the same file really.

Basically it's a reasonably common property of some files in a file system - why would Java not want to expose that information?

Answer 2

One really good reason you might care about symbolic links is because of security. Sometimes you might want to prevent letting people accessing files from outside a restricted area, so your app checks to make sure the file that is being accessed is not a symbolic link that leads outside of your application's sandbox.

For example, if you're building a network accessible application that runs as a user and that accesses files by path, like maybe a file sharing application, and you want to restrict where people can look for files on your users system, symbolic links could be a security problem.