org.apache.commons.pool
Class BaseObjectPool

java.lang.Object
  org.apache.commons.pool.BaseObjectPool

All Implemented Interfaces:

ObjectPool

Direct Known Subclasses:

GenericObjectPool, SoftReferenceObjectPool, StackObjectPool

public abstract class BaseObjectPool
extends Object
implements ObjectPool

A simple base implementation of ObjectPool. Optional operations are implemented to either do nothing, return a value indicating it is unsupported or throw UnsupportedOperationException.

Since:

Pool 1.0

Version:

$Revision: 480413 $ $Date: 2006-11-28 22:16:05 -0700 (Tue, 28 Nov 2006) $

Constructor Summary

BaseObjectPool()

Method Summary

void	addObject() Not supported in this base implementation.
protected void	assertOpen() Throws an IllegalStateException when this pool has been closed.
abstract Object	borrowObject() Obtains an instance from this pool.
void	clear() Not supported in this base implementation.
void	close() Close this pool.
int	getNumActive() Not supported in this base implementation.
int	getNumIdle() Not supported in this base implementation.
abstract void	invalidateObject(Object obj) Invalidates an object from the pool By contract, obj must have been obtained using borrowObject or a related method as defined in an implementation or sub-interface.
protected boolean	isClosed() Has this pool instance been closed.
abstract void	returnObject(Object obj) Return an instance to the pool.
void	setFactory(PoolableObjectFactory factory) Not supported in this base implementation.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

BaseObjectPool

public BaseObjectPool()

Method Detail

borrowObject

public abstract Object borrowObject()
                             throws Exception

Description copied from interface: ObjectPool

Obtains an instance from this pool.

Instances returned from this method will have been either newly created with makeObject or will be a previously idle object and have been activated with activateObject and then validated with validateObject.

By contract, clients must return the borrowed instance using returnObject, invalidateObject, or a related method as defined in an implementation or sub-interface.

The behaviour of this method when the pool has been exhausted is not strictly specified (although it may be specified by implementations). Older versions of this method would return null to indicate exhaustion, newer versions are encouraged to throw a NoSuchElementException.

Specified by:

borrowObject in interface ObjectPool

Returns:

an instance from this pool.

Throws:

IllegalStateException - after close has been called on this pool.

Exception - when makeObject throws an exception.

NoSuchElementException - when the pool is exhausted and cannot or will not return another instance.

returnObject

public abstract void returnObject(Object obj)
                           throws Exception

Description copied from interface: ObjectPool

Return an instance to the pool. By contract, obj must have been obtained using borrowObject or a related method as defined in an implementation or sub-interface.

Specified by:

returnObject in interface ObjectPool

Parameters:

obj - a borrowed instance to be returned.

Throws:

Exception - deprecated: as of Pool 2.0 pool implementations should swallow exceptions that occur when a poolable object is returned. For future source compatability implementations of this method should not even declare that they throw any exception.

invalidateObject

public abstract void invalidateObject(Object obj)
                               throws Exception

Description copied from interface: ObjectPool

Invalidates an object from the pool By contract, obj must have been obtained using borrowObject or a related method as defined in an implementation or sub-interface.

This method should be used when an object that has been borrowed is determined (due to an exception or other problem) to be invalid.

Specified by:

invalidateObject in interface ObjectPool

Parameters:

obj - a borrowed instance to be disposed.

Throws:

Exception - deprecated: as of Pool 2.0 pool implementations should swallow exceptions that occur when a poolable object is returned. For future source compatability implementations of this method should not even declare that they throw any exception.

getNumIdle

public int getNumIdle()
               throws UnsupportedOperationException

Not supported in this base implementation.

Specified by:

getNumIdle in interface ObjectPool

Returns:

a negative value.

Throws:

UnsupportedOperationException - deprecated: if this implementation does not support the operation

getNumActive

public int getNumActive()
                 throws UnsupportedOperationException

Not supported in this base implementation.

Specified by:

getNumActive in interface ObjectPool

Returns:

a negative value.

Throws:

UnsupportedOperationException - deprecated: if this implementation does not support the operation

clear

public void clear()
           throws Exception,
                  UnsupportedOperationException

Not supported in this base implementation.

Specified by:

clear in interface ObjectPool

Throws:

UnsupportedOperationException - if this implementation does not support the operation

Exception

addObject

public void addObject()
               throws Exception,
                      UnsupportedOperationException

Not supported in this base implementation. Always throws an UnsupportedOperationException, subclasses should override this behavior.

Specified by:

addObject in interface ObjectPool

Throws:

Exception - when PoolableObjectFactory.makeObject() fails.

IllegalStateException - after ObjectPool.close() has been called on this pool.

UnsupportedOperationException - when this pool cannot add new idle objects.

close

public void close()
           throws Exception

Close this pool. This affects the behavior of isClosed and assertOpen.

Specified by:

close in interface ObjectPool

Throws:

Exception - deprecated: implementations should silently fail if not all resources can be freed.

setFactory

public void setFactory(PoolableObjectFactory factory)
                throws IllegalStateException,
                       UnsupportedOperationException

Not supported in this base implementation. Always throws an UnsupportedOperationException, subclasses should override this behavior.

Specified by:

setFactory in interface ObjectPool

Parameters:

factory - the PoolableObjectFactory used to create new instances.

Throws:

IllegalStateException - when the factory cannot be set at this time

UnsupportedOperationException - if this implementation does not support the operation

isClosed

protected final boolean isClosed()

Has this pool instance been closed.

Returns:

true when this pool has been closed.

assertOpen

protected final void assertOpen()
                         throws IllegalStateException

Throws an IllegalStateException when this pool has been closed.

Throws:

IllegalStateException - when this pool has been closed.

See Also:

isClosed()