org.apache.commons.pool

Interface ObjectPool

All Known Implementing Classes:

BaseObjectPool, GenericObjectPool, SoftReferenceObjectPool, StackObjectPool

public interface ObjectPool

A pooling interface.

ObjectPool defines a trivially simple pooling interface. The only required methods are borrowObject and returnObject.

Example of use:

Object obj = null; try { obj = pool.borrowObject(); //...use the object... } catch(Exception e) { //...handle any exceptions... } finally { // make sure the object is returned to the pool if(null != obj) { pool.returnObject(obj); } }

See BaseObjectPool for a simple base implementation.

Version:

$Revision: 155430 $ $Date: 2005-02-26 08:13:28 -0500 (Sat, 26 Feb 2005) $

Author:

Rodney Waldhoff

Method Summary

Methods

Modifier and Type	Method and Description
void	addObject() Create an object using my factory or other implementation dependent mechanism, and place it into the pool.
java.lang.Object	borrowObject() Obtain an instance from my pool.
void	clear() Clears any objects sitting idle in the pool, releasing any associated resources (optional operation).
void	close() Close this pool, and free any resources associated with it.
int	getNumActive() Return the number of instances currently borrowed from my pool (optional operation).
int	getNumIdle() Return the number of instances currently idle in my pool (optional operation).
void	invalidateObject(java.lang.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.
void	returnObject(java.lang.Object obj) Return an instance to my pool.
void	setFactory(PoolableObjectFactory factory) Sets the factory I use to create new instances (optional operation).

Method Detail

addObject

void addObject()
               throws java.lang.Exception

Create an object using my factory or other implementation dependent mechanism, and place it into the pool. addObject() is useful for "pre-loading" a pool with idle objects. (Optional operation).

Throws:

java.lang.Exception

borrowObject

java.lang.Object borrowObject()
                              throws java.lang.Exception

Obtain an instance from my pool. By contract, clients MUST return the borrowed instance using returnObject 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 specified (although it may be specified by implementations).

Returns:

an instance from my pool.

Throws:

java.lang.Exception

clear

void clear()
           throws java.lang.Exception,
                  java.lang.UnsupportedOperationException

Clears any objects sitting idle in the pool, releasing any associated resources (optional operation).

Throws:

java.lang.UnsupportedOperationException - if this implementation does not support the operation

java.lang.Exception

close

void close()
           throws java.lang.Exception

Close this pool, and free any resources associated with it.

Throws:

java.lang.Exception

getNumActive

int getNumActive()
                 throws java.lang.UnsupportedOperationException

Return the number of instances currently borrowed from my pool (optional operation).

Returns:

the number of instances currently borrowed in my pool

Throws:

java.lang.UnsupportedOperationException - if this implementation does not support the operation

getNumIdle

int getNumIdle()
               throws java.lang.UnsupportedOperationException

Return the number of instances currently idle in my pool (optional operation). This may be considered an approximation of the number of objects that can be borrowed without creating any new instances.

Returns:

the number of instances currently idle in my pool

Throws:

java.lang.UnsupportedOperationException - if this implementation does not support the operation

invalidateObject

void invalidateObject(java.lang.Object obj)
                      throws java.lang.Exception

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. If the connection should be validated before or after borrowing, then the PoolableObjectFactory.validateObject(java.lang.Object) method should be used instead.

Parameters:

obj - a borrowed instance to be returned.

Throws:

java.lang.Exception

returnObject

void returnObject(java.lang.Object obj)
                  throws java.lang.Exception

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

Parameters:

obj - a borrowed instance to be returned.

Throws:

java.lang.Exception

setFactory

void setFactory(PoolableObjectFactory factory)
                throws java.lang.IllegalStateException,
                       java.lang.UnsupportedOperationException

Sets the factory I use to create new instances (optional operation).

Parameters:

factory - the PoolableObjectFactory I use to create new instances.

Throws:

java.lang.IllegalStateException - when the factory cannot be set at this time

java.lang.UnsupportedOperationException - if this implementation does not support the operation