WebNFS Developer's Guide

How Do I Lock a File Using the Extended Filesystem API?

The Extended Filesystem API mirrors the file access functions available through the Java I/O package java.io. Neither package supports the ability to lock files. NFS clients generally lock files using the companion NLM (Network Lock Manager) protocol but this is not currently implemented in the Java NFS client. Where locking is not supported directly, applications can use a lock file as a substitute.