MacOS 上 Java 目录 WatchService 的状态

Question

What is the status for WatchService on the Java platform for MacOS?

Seems not to have been working on 7 and 8.

Has that been resolved in later versions? We are on 13 now.

Answer 1

From what I can see, it's working on MacOS with OpenJDK 8.

/tmp$ java DirectoryWatcherExample                        
Event kind:ENTRY_CREATE. File affected: test.txt.                               
Event kind:ENTRY_DELETE. File affected: test.txt.                               
Event kind:ENTRY_CREATE. File affected: test.txt.                               
Event kind:ENTRY_MODIFY. File affected: test.txt.                               
Event kind:ENTRY_DELETE. File affected: test.txt.                               

/tmp$ java -version                                     
openjdk version "1.8.0_232"                                                     
OpenJDK Runtime Environment (AdoptOpenJDK)(build 1.8.0_232-b09)                 
OpenJDK 64-Bit Server VM (AdoptOpenJDK)(build 25.232-b09, mixed mode)          

/tmp$ uname -v                                            
Darwin Kernel Version 18.7.0: Sat Oct 12 00:02:19 PDT 2019; root:xnu-4903.278.12
~1/RELEASE_X86_64

You can try the code out DirectoryWatcherExample.java

Original source: A guide to WatchService in Java NIO2

JDK seems to have the implementation of a mechanism called kevent which is the notification mechanism for OpenBSD/solaris based systems. I have no experience with searching mercurial repos, so the best I can find is a readonly JDK8 source that shows the kqueue implementation.

• Kqueue.java
• Related to the native implementation; KQueueArrayWrapper.c
• Macos manpage for kevent