Package io.methvin.watcher.hashing

Interface FileHasher

Functional Interface:
This is a functional interface and can therefore be used as the assignment target for a lambda expression or method reference.
@FunctionalInterface
public interface FileHasher
A function to convert a Path to a hash code used to check if the file content is changed. This is called by DirectoryWatcher after checking that the path exists and is not a directory. Therefore this hasher can generally assume that those two things are true.

By default, this hasher may throw an IOException, which will be treated as a `null` hash by the watcher, meaning the associated event will be ignored. If you want to handle that exception you can catch/rethrow it.

  • Field Summary

    Fields
    Modifier and Type Field Description
    static FileHasher DEFAULT_FILE_HASHER
    The default file hasher instance, which uses Murmur3.
    static FileHasher LAST_MODIFIED_TIME
    A file hasher that returns the last modified time provided by the OS.

  • Method Summary

    Modifier and Type Method Description
    FileHash hash​(java.nio.file.Path path)  

  • Field Details

    • DEFAULT_FILE_HASHER

      static final FileHasher DEFAULT_FILE_HASHER
      The default file hasher instance, which uses Murmur3.

    • LAST_MODIFIED_TIME

      static final FileHasher LAST_MODIFIED_TIME
      A file hasher that returns the last modified time provided by the OS.

      This only works reliably on certain file systems and JDKs that support at least millisecond-level precision.

  • Method Details

    • hash

      FileHash hash​(java.nio.file.Path path) throws java.io.IOException
      Throws:
      java.io.IOException