Spring Framework

Class WeakReferenceMonitor

  extended by org.springframework.util.WeakReferenceMonitor

public class WeakReferenceMonitor
extends java.lang.Object

Track references to arbitrary objects using proxy and weak references. To monitor a handle, one should call monitor(Object, ReleaseListener), with the given handle object usually being a holder that uses the target object underneath, and the release listener performing cleanup of the target object once the handle is not strongly referenced anymore.

When a given handle becomes weakly reachable, the specified listener will be called by a background thread. This thread will only be started lazily and will be stopped once no handles are registered for monitoring anymore, to be restarted if further handles are added.

Thanks to Tomasz Wysocki for the suggestion and the original implementation of this class!

Colin Sampaleanu, Juergen Hoeller
See Also:
monitor(java.lang.Object, org.springframework.util.WeakReferenceMonitor.ReleaseListener)

Nested Class Summary
static interface WeakReferenceMonitor.ReleaseListener
          Listener that is notified when the handle is being released.
Constructor Summary
Method Summary
static void monitor(java.lang.Object handle, WeakReferenceMonitor.ReleaseListener listener)
          Start to monitor given handle object for becoming weakly reachable.
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail


public WeakReferenceMonitor()
Method Detail


public static void monitor(java.lang.Object handle,
                           WeakReferenceMonitor.ReleaseListener listener)
Start to monitor given handle object for becoming weakly reachable. When the handle isn't used anymore, the given listener will be called.

handle - the object that will be monitored
listener - the listener that will be called upon release of the handle

Spring Framework