K - the type of keys in this poolV - the type of objects held in this poolpublic interface KeyedObjectPool<K,V>
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) {// invalidate the objectpool.invalidateObject(key, obj);// do not return the object to the pool twiceobj =null; }finally{// make sure the object is returned to the poolif(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 Map of
 pools).
 
See BaseKeyedObjectPool for a simple base implementation.
KeyedPoolableObjectFactory, 
KeyedObjectPoolFactory, 
ObjectPool, 
BaseKeyedObjectPool| Modifier and Type | Method and Description | 
|---|---|
| void | addObject(K key)Create an object using the  factoryor other
 implementation dependent mechanism, passivate it, and then place it in the idle object pool. | 
| V | borrowObject(K key)Obtains an instance from this pool for the specified  key. | 
| void | clear()Clears the pool, removing all pooled instances (optional operation). | 
| void | clear(K key)Clears the specified pool, removing all
 pooled instances corresponding to
 the given  key(optional operation). | 
| void | close()Close this pool, and free any resources associated with it. | 
| int | getNumActive()Returns the total number of instances
 current borrowed from this pool but not
 yet returned (optional operation). | 
| int | getNumActive(K key)Returns the number of instances
 currently borrowed from but not yet returned
 to the pool corresponding to the
 given  key(optional operation). | 
| int | getNumIdle()Returns the total number of instances
 currently idle in this pool (optional operation). | 
| int | getNumIdle(K key)Returns the number of instances
 corresponding to the given  keycurrently idle in this pool (optional operation). | 
| void | invalidateObject(K key,
                V obj)Invalidates an object from the pool. | 
| void | returnObject(K key,
            V obj)Return an instance to the pool. | 
| void | setFactory(KeyedPoolableObjectFactory<K,V> factory)Deprecated. 
 to be removed in pool 2.0 | 
V borrowObject(K key) throws Exception, NoSuchElementException, IllegalStateException
key.
 
 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 object using
 returnObject, invalidateObject, 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.
 
 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.
key - the key used to obtain the objectIllegalStateException - after close has been called on this poolException - when makeObject throws an exceptionNoSuchElementException - when the pool is exhausted and cannot or will not return another instancevoid returnObject(K key, V obj) throws Exception
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 instance in the first place.void invalidateObject(K key, V obj) throws 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 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.
void addObject(K key) throws Exception, IllegalStateException, UnsupportedOperationException
factory or other
 implementation dependent mechanism, passivate it, and then place it in the idle object pool.
 addObject is useful for "pre-loading" a pool with idle objects
 (Optional operation).key - the key a new instance should be added toException - when KeyedPoolableObjectFactory.makeObject(K) fails.IllegalStateException - after close() has been called on this pool.UnsupportedOperationException - when this pool cannot add new idle objects.int getNumIdle(K key) throws UnsupportedOperationException
key
 currently idle in this pool (optional operation).
 Returns a negative value if this information is not available.key - the key to querykey currently idle in this pool or a negative value if unsupportedUnsupportedOperationException - deprecated: when this implementation doesn't support the operationint getNumActive(K key) throws UnsupportedOperationException
key (optional operation).
 Returns a negative value if this information is not available.key - the key to querykey currently borrowed in this pool or a negative value if unsupportedUnsupportedOperationException - deprecated: when this implementation doesn't support the operationint getNumIdle()
               throws UnsupportedOperationException
UnsupportedOperationException - deprecated: when this implementation doesn't support the operationint getNumActive()
                 throws UnsupportedOperationException
UnsupportedOperationException - deprecated: when this implementation doesn't support the operationvoid clear()
           throws Exception,
                  UnsupportedOperationException
UnsupportedOperationException if the pool cannot be cleared.UnsupportedOperationException - when this implementation doesn't support the operationExceptionvoid clear(K key) throws Exception, UnsupportedOperationException
key (optional operation).
 Throws UnsupportedOperationException if the pool cannot be cleared.key - the key to clearUnsupportedOperationException - when this implementation doesn't support the operationExceptionvoid close()
           throws Exception
 Calling addObject or borrowObject after invoking
 this method on a pool will cause them to throw an IllegalStateException.
 
Exception@Deprecated void setFactory(KeyedPoolableObjectFactory<K,V> factory) throws IllegalStateException, UnsupportedOperationException
factory the pool uses
 to create new instances (optional operation).
 Trying to change the factory after a pool has been used will frequently
 throw an UnsupportedOperationException. It is up to the pool
 implementation to determine when it is acceptable to call this method.factory - the KeyedPoolableObjectFactory used to create new instances.IllegalStateException - when the factory cannot be set at this timeUnsupportedOperationException - when this implementation doesn't support the operationCopyright © 2000-2020 Apache Software Foundation. All Rights Reserved.