Interface KeyedObjectPool<K,V>
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- Type Parameters:
K- the type of keys in this poolV- the type of objects held in this pool
- All Known Implementing Classes:
BaseKeyedObjectPool,GenericKeyedObjectPool,StackKeyedObjectPool
public interface KeyedObjectPool<K,V>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) {// 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); } }KeyedObjectPoolimplementations 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 aMapofpools).See
BaseKeyedObjectPoolfor a simple base implementation.- Since:
- Pool 1.0
- Version:
- $Revision: 1222396 $ $Date: 2011-12-22 14:02:25 -0500 (Thu, 22 Dec 2011) $
- Author:
- Rodney Waldhoff, Sandy McArthur
- See Also:
KeyedPoolableObjectFactory,KeyedObjectPoolFactory,ObjectPool,BaseKeyedObjectPool
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Method Summary
All Methods Instance Methods Abstract Methods Modifier and Type Method Description voidaddObject(K key)Create an object using thefactoryor other implementation dependent mechanism, passivate it, and then place it in the idle object pool.VborrowObject(K key)Obtains an instance from this pool for the specifiedkey.voidclear()Clears the pool, removing all pooled instances (optional operation).voidclear(K key)Clears the specified pool, removing all pooled instances corresponding to the givenkey(optional operation).voidclose()Close this pool, and free any resources associated with it.intgetNumActive()Returns the total number of instances current borrowed from this pool but not yet returned (optional operation).intgetNumActive(K key)Returns the number of instances currently borrowed from but not yet returned to the pool corresponding to the givenkey(optional operation).intgetNumIdle()Returns the total number of instances currently idle in this pool (optional operation).intgetNumIdle(K key)Returns the number of instances corresponding to the givenkeycurrently idle in this pool (optional operation).voidinvalidateObject(K key, V obj)Invalidates an object from the pool.voidreturnObject(K key, V obj)Return an instance to the pool.
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Method Detail
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borrowObject
V borrowObject(K key) throws java.lang.Exception, java.util.NoSuchElementException, java.lang.IllegalStateException
Obtains an instance from this pool for the specifiedkey.Instances returned from this method will have been either newly created with
makeObjector will be a previously idle object and have been activated withactivateObjectand then validated withvalidateObject.By contract, clients must return the borrowed object using
returnObject,invalidateObject, or a related method as defined in an implementation or sub-interface, using akeythat isequivalentto 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
nullto indicate exhaustion, newer versions are encouraged to throw aNoSuchElementException.- Parameters:
key- the key used to obtain the object- Returns:
- an instance from this pool.
- Throws:
java.lang.IllegalStateException- afterclosehas been called on this pooljava.lang.Exception- whenmakeObjectthrows an exceptionjava.util.NoSuchElementException- when the pool is exhausted and cannot or will not return another instance
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returnObject
void returnObject(K key, V obj) throws java.lang.Exception
Return an instance to the pool. By contract,objmust have been obtained usingborrowObjector a related method as defined in an implementation or sub-interface using akeythat is equivalent to the one used to borrow the instance in the first place.- Parameters:
key- the key used to obtain the objectobj- aborrowedinstance to be returned.- Throws:
java.lang.Exception
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invalidateObject
void invalidateObject(K key, V obj) throws java.lang.Exception
Invalidates an object from the pool.
By contract,
objmust have been obtained usingborrowObjector a related method as defined in an implementation or sub-interface using akeythat is equivalent to the one used to borrow theObjectin 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.
- Parameters:
key- the key used to obtain the objectobj- aborrowedinstance to be returned.- Throws:
java.lang.Exception
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addObject
void addObject(K key) throws java.lang.Exception, java.lang.IllegalStateException, java.lang.UnsupportedOperationException
Create an object using thefactoryor other implementation dependent mechanism, passivate it, and then place it in the idle object pool.addObjectis useful for "pre-loading" a pool with idle objects (Optional operation).- Parameters:
key- the key a new instance should be added to- Throws:
java.lang.Exception- whenKeyedPoolableObjectFactory.makeObject(K)fails.java.lang.IllegalStateException- afterclose()has been called on this pool.java.lang.UnsupportedOperationException- when this pool cannot add new idle objects.
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getNumIdle
int getNumIdle(K key) throws java.lang.UnsupportedOperationException
Returns the number of instances corresponding to the givenkeycurrently idle in this pool (optional operation). Returns a negative value if this information is not available.- Parameters:
key- the key to query- Returns:
- the number of instances corresponding to the given
keycurrently idle in this pool or a negative value if unsupported - Throws:
java.lang.UnsupportedOperationException- deprecated: when this implementation doesn't support the operation
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getNumActive
int getNumActive(K key) throws java.lang.UnsupportedOperationException
Returns the number of instances currently borrowed from but not yet returned to the pool corresponding to the givenkey(optional operation). Returns a negative value if this information is not available.- Parameters:
key- the key to query- Returns:
- the number of instances corresponding to the given
keycurrently borrowed in this pool or a negative value if unsupported - Throws:
java.lang.UnsupportedOperationException- deprecated: when this implementation doesn't support the operation
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getNumIdle
int getNumIdle() throws java.lang.UnsupportedOperationExceptionReturns the total number of instances currently idle in this pool (optional operation). Returns a negative value if this information is not available.- Returns:
- the total number of instances currently idle in this pool or a negative value if unsupported
- Throws:
java.lang.UnsupportedOperationException- deprecated: when this implementation doesn't support the operation
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getNumActive
int getNumActive() throws java.lang.UnsupportedOperationExceptionReturns the total number of instances current borrowed from this pool but not yet returned (optional operation). Returns a negative value if this information is not available.- Returns:
- the total number of instances currently borrowed from this pool or a negative value if unsupported
- Throws:
java.lang.UnsupportedOperationException- deprecated: when this implementation doesn't support the operation
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clear
void clear() throws java.lang.Exception, java.lang.UnsupportedOperationExceptionClears the pool, removing all pooled instances (optional operation). ThrowsUnsupportedOperationExceptionif the pool cannot be cleared.- Throws:
java.lang.UnsupportedOperationException- when this implementation doesn't support the operationjava.lang.Exception
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clear
void clear(K key) throws java.lang.Exception, java.lang.UnsupportedOperationException
Clears the specified pool, removing all pooled instances corresponding to the givenkey(optional operation). ThrowsUnsupportedOperationExceptionif the pool cannot be cleared.- Parameters:
key- the key to clear- Throws:
java.lang.UnsupportedOperationException- when this implementation doesn't support the operationjava.lang.Exception
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close
void close() throws java.lang.ExceptionClose this pool, and free any resources associated with it.Calling
addObjectorborrowObjectafter invoking this method on a pool will cause them to throw anIllegalStateException.- Throws:
java.lang.Exception
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