How to automatically reload a changing file in liberty - reload

Question

experts.
I need to reload a file when it updated automatically in Liberty. To make it more clear, I want to make a path like "dropins" in liberty, it can automatically detect the change of files or we can scan this folder manually. I need to load the files in this folder when they changed.
I've no idea how to achieve this....
Could anyone here know about it?
Thx!

Answer 1

If you are not averse to writing a Liberty feature (not hard, but requires a little background reading), then you can register a listener for changes to specific files by implementing the com.ibm.wsspi.kernel.filemonitor.FileMonitor interface as a Declarative Service. Once registered as a DS, the Liberty file monitor will invoke your implementation's methods. It invokes onBaseline(Collection<File> baseline) on startup, and onChange(Collection<File> createdFiles, Collection<File> modifiedFiles, Collection<File> deletedFiles) when a change of some sort has occurred.
One implementation might look like this:
#Component(immediate="true", property={"monitor.directories=/path/to/myMonitoredDir"})
public class MyFileMonitor implements FileMonitor {
#Override
public void onBaseline(Collection<File> baseline) {
System.out.println("Initial file state:");
for (File f : baseline) {
System.out.println(f.getName());
}
}
#Override
public void onChange(Collection<File> createdFiles, Collection<File> modifiedFiles, Collection<File> deletedFiles) {
System.out.println("Newly added files:");
for (File f : createdFiles) {
System.out.println(f.getName());
}
System.out.println("Newly deleted files:");
for (File f : deletedFiles) {
System.out.println(f.getName());
}
System.out.println("Modified files:");
for (File f : modifiedFiles) {
System.out.println(f.getName());
}
}
}
Hope this helps,
Andy