org.apache.commons.pool

Interface KeyedObjectPool

public interface KeyedObjectPool

A "keyed" pooling interface.

A keyed pool pools instances of multiple types. Each type may be accessed using an arbitrary key.

Example of use:

 Object obj = null;
 Object key = "Key";

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

KeyedObjectPool implementations may choose to store at most one instance per key value, or may choose to maintain a pool of instances for each key (essentially creating a java.util.Map Map of pools).

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

Author: Rodney Waldhoff

See Also: KeyedPoolableObjectFactory KeyedObjectPoolFactory

Method Summary
voidaddObject(Object key)
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.
ObjectborrowObject(Object key)
Obtain an instance from my pool for the specified key.
voidclear()
Clears my pool, removing all pooled instances (optional operation).
voidclear(Object key)
Clears the specified pool, removing all pooled instances corresponding to the given key (optional operation).
voidclose()
Close this pool, and free any resources associated with it.
intgetNumActive(Object key)
Returns the number of instances currently borrowed from but not yet returned to my pool corresponding to the given key (optional operation).
intgetNumActive()
Returns the total number of instances current borrowed from my pool but not yet returned (optional operation).
intgetNumIdle(Object key)
Returns the number of instances corresponding to the given key currently idle in my pool (optional operation).
intgetNumIdle()
Returns the total number of instances currently idle in my pool (optional operation).
voidinvalidateObject(Object key, 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 using a key that is equivalent to the one used to borrow the Object in the first place.
voidreturnObject(Object key, Object obj)
Return an instance to my pool.
voidsetFactory(KeyedPoolableObjectFactory factory)
Sets the factory I use to create new instances (optional operation).

Method Detail

addObject

public void addObject(Object key)
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).

borrowObject

public Object borrowObject(Object key)
Obtain an instance from my pool for the specified key. By contract, clients MUST return the borrowed object using returnObject, or a related method as defined in an implementation or sub-interface, using a key that is equivalent to the one used to borrow the instance in the first place.

Parameters: key the key used to obtain the object

Returns: an instance from my pool.

clear

public void clear()
Clears my pool, removing all pooled instances (optional operation). Throws UnsupportedOperationException if the pool cannot be cleared.

Throws: UnsupportedOperationException when this implementation doesn't support the operation

clear

public void clear(Object key)
Clears the specified pool, removing all pooled instances corresponding to the given key (optional operation). Throws UnsupportedOperationException if the pool cannot be cleared.

Parameters: key the key to clear

Throws: UnsupportedOperationException when this implementation doesn't support the operation

close

public void close()
Close this pool, and free any resources associated with it.

getNumActive

public int getNumActive(Object key)
Returns the number of instances currently borrowed from but not yet returned to my pool corresponding to the given key (optional operation). Throws UnsupportedOperationException if this information is not available.

Parameters: key the key

Returns: the number of instances corresponding to the given key currently borrowed in my pool

Throws: UnsupportedOperationException when this implementation doesn't support the operation

getNumActive

public int getNumActive()
Returns the total number of instances current borrowed from my pool but not yet returned (optional operation). Throws UnsupportedOperationException if this information is not available.

Returns: the total number of instances currently borrowed from my pool

Throws: UnsupportedOperationException when this implementation doesn't support the operation

getNumIdle

public int getNumIdle(Object key)
Returns the number of instances corresponding to the given key currently idle in my pool (optional operation). Throws UnsupportedOperationException if this information is not available.

Parameters: key the key

Returns: the number of instances corresponding to the given key currently idle in my pool

Throws: UnsupportedOperationException when this implementation doesn't support the operation

getNumIdle

public int getNumIdle()
Returns the total number of instances currently idle in my pool (optional operation). Throws UnsupportedOperationException if this information is not available.

Returns: the total number of instances currently idle in my pool

Throws: UnsupportedOperationException when this implementation doesn't support the operation

invalidateObject

public void invalidateObject(Object key, 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 using a key that is equivalent to the one used to borrow the Object in the first place.

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 method should be used instead.

Parameters: obj a borrowed instance to be returned.

returnObject

public void returnObject(Object key, Object obj)
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 using a key that is equivalent to the one used to borrow the Object in the first place.

Parameters: key the key used to obtain the object obj a borrowed instance to be returned.

setFactory

public void setFactory(KeyedPoolableObjectFactory factory)
Sets the factory I use to create new instances (optional operation).

Parameters: factory the KeyedPoolableObjectFactory I use to create new instances.

Throws: IllegalStateException when the factory cannot be set at this time UnsupportedOperationException when this implementation doesn't support the operation

Copyright © 2001-2003 Apache Software Foundation. Documenation generated August 23 2012.