How to implement file watcher in java?

How to implement file watcher in java?

Here are the basic steps required to implement a watch service:

1. Create a WatchService “watcher” for the file system.
2. For each directory that you want monitored, register it with the watcher.
3. Implement an infinite loop to wait for incoming events.
4. Retrieve the key from the watcher’s queue.

What is WatchService in java?

A watch service that watches registered objects for changes and events. For example a file manager may use 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.

Can we monitor a directory for adding new files in java?

Create a Path object representing the directory to monitor for file events. Path path = Paths. get(“/home/omkar/test”); Implement the FileHandler interface to perform an action detected by file event registered.

What is inotify on Linux?

inotify (inode notify) is a Linux kernel subsystem created by John McCutchan, which monitors changes to the filesystem, and reports those changes to applications. It can be used to automatically update directory views, reload configuration files, log changes, backup, synchronize, and upload.

What is JNotify?

JNotify is a java library that allow java application to listen to file system events, such as: File created. File modified. File renamed. File deleted.

What is the relationship between a WatchKey instance and a WatchService instance?

The WatchKey This class represents the registration of a directory with the watch service. Its instance is returned to us by the watch service when we register a directory and when we ask the watch service if any events we registered for have occurred.

How do I set up inotify?

To install inotify-tools on a server:

1. Download and store the source code file for inotify-tools on the Linux server.
2. Log in as root.
3. Decompress the source code file, as shown in Figure 72.
4. Enter the inotify-tools-3.14 directory, as shown in Figure 73.
5. Configure the installation directory for inotify-tools.

What is the inotify API?

The inotify API provides a mechanism for monitoring filesystem events. Inotify can be used to monitor individual files, or to monitor directories. When a directory is monitored, inotify will return events for the directory itself, and for files inside the directory.

How does inotify work with directory monitoring?

When a directory is monitored, inotify will return events for the directory itself, and for files inside the directory. The following system calls are used with this API: * inotify_init (2) creates an inotify instance and returns a file descriptor referring to the inotify instance.

What is inotify_RM_Watch (2)?

* When events occur for monitored files and directories, those events are made available to the application as structured data that can be read from the inotify file descriptor using read (2) (see below). * inotify_rm_watch (2) removes an item from an inotify watch list.

What does inotify_add_watch do?

Each item (“watch”) in the watch list specifies the pathname of a file or directory, along with some set of events that the kernel should monitor for the file referred to by that pathname. inotify_add_watch (2) either creates a new watch item, or modifies an existing watch.