file watcher

Watches for file system changes or event. It uses a watch service to monitor a directory for changes so that it can update its display of the list of files when files are created or deleted.

dependency

<dependency>
 <groupId>org.jooby</groupId>
 <artifactId>jooby-file watcher</artifactId>
 <version>1.6.6</version>
</dependency>

usage

Watch mydir and listen for create, modify or delete event on all files under it:

{
  use(new FileWatcher()
    .register(Paths.get("mydir"), (kind, path) -> {
      log.info("found {} on {}", kind, path);
    });
  );
}

file handler

You can specify a {@link FileEventHandler} instance or class while registering a path:

Instance:

{
  use(new FileWatcher()
    .register(Paths.get("mydir"), (kind, path) -> {
      log.info("found {} on {}", kind, path);
    });
  );
}

Class reference:

{
  use(new FileWatcher()
    .register(Paths.get("mydir"), MyFileEventHandler.class)
  );
}

Worth to mention that MyFileEventHandler will be provided by Guice.

options

You can specify a couple of options at registration time:

{
  use(new FileWatcher(
    .register(Paths.get("mydir"), MyFileEventHandler.class, options -> {
      options.kind(StandardWatchEventKinds.ENTRY_MODIFY)
             .recursive(false)
             .includes("*.java");
    });
  ));
}

Here we listen for {@link StandardWatchEventKinds#ENTRY_MODIFY} (we don’t care about create or delete).
We turn off recursive watching, only direct files are detected.
We want .java files and we ignore any other files.

configuration file

In addition to do it programmatically, you can do it via configuration properties:

{
  use(new FileWatcher()
    .register("mydirproperty", MyEventHandler.class)
  );
}

The mydirproperty property must be present in your .conf file.

But of course, you can entirely register paths from .conf file:

filewatcher {
  register {
    path: "mydir"
    handler: "org.example.MyFileEventHandler"
    kind: "ENTRY_MODIFY"
    includes: "*.java"
    recursive: false
  }
}

Multiple paths are supported using array notation:

filewatcher {
  register: [{
    path: "mydir1"
    handler: "org.example.MyFileEventHandler"
  }, {
    path: "mydir2"
    handler: "org.example.MyFileEventHandler"
  }]
}

Now use the module:

{
  use(new FileWatcher());
}

The FileWatcher module read the filewatcher.register property and setup everything.