CODEWITHSUNDEEP
javapathniojava-7
ripper234
ripper234

Reputation: 230048

How to access a sub-file/folder in Java 7 java.nio.file.Path?

Java 7 introduced java.nio.file.Path as a possible replacement for java.io.File.

With File, when I access a file under a specific, I would do:

File parent = new File("c:\\tmp");
File child = new File(parent, "child"); // this accesses c:\tmp\child

What's the way to do this with Path?

I supposed this will work:

Path parent = Paths.get("c:\\tmp");
Path child = Paths.get(parent.toString(), "child");

But calling parent.toString() seems ugly. Is there a better way?

Upvotes: 75

Views: 30592

Answers (2)

Ryan Leach
Ryan Leach

Reputation: 4470

To anyone finding this question looking specifically only for files that are within the specified path, you must be aware of path traversal attacks.

See: Filtering upwards path traversal in Java (or Scala)

It is critical that you check that the path starts with the root.

Path parent = Paths.get("C:\\tmp");
Path child = parent.resolve("chlid").normalize();
if (!child.startsWith(parent)) {
    throw new IllegalArgumentException("Potential Path Traversal Attack");
}

Upvotes: 0

Erick Robertson
Erick Robertson

Reputation: 33078

Use the resolve method on Path.

There are two methods with this name. One takes a relative Path and the other a String. It uses the Path on which it is called as a parent and appends the String or relative Path appropriately.

Path parent = Paths.get("c:\\tmp");
Path child = parent.resolve("child");

Upvotes: 109

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