com.bankframe.services.cache
Class GenericCache

java.lang.Object
  com.bankframe.services.cache.GenericCache

All Implemented Interfaces:

Cache, NamedCache, PersistentCache, Map

Direct Known Subclasses:

JMSCacheImpl, MergedDataPacketsCache, ThreadCleanedCache

public class GenericCache
extends Object
implements PersistentCache, NamedCache

This class provides generic caching functionality using a local cache. It implements the java.util.Map interface. This class uses the supplied Map implementation to maintain consistency between the cache and the data store. The supplied Map implementation must store and read its contents from some permanent data store. An object will remain in the cache until it expires. When the object expires is determined by the CachePolicy object. The Cache policy's cleanup() method will be called at the end of the following methods:

• get() - If and only if the get() request could not be fulfilled from the Cache
• put()
• putAll()
• remove()

Note: The default policy used if one is not specified is the NullPolicy.

Nested Class Summary

Nested classes/interfaces inherited from interface java.util.Map

Map.Entry<K,V>

Constructor Summary

GenericCache()
Default Constructor

GenericCache(CachePolicy policy)
Constructor

GenericCache(Map persistentMap)
Constructor

GenericCache(Map persistentMap, CachePolicy policy)
Constructor

Method Summary

void	addCacheListener(Object key, CacheListener listener) Adds a CacheListener for a specified key.
void	cleanup() This method cleans up the cache by removing un-needed entries
void	clear() This method clears the cache.
boolean	containsKey(Object key)
boolean	containsValue(Object value)
void	enableCaching(boolean enableCache) This method enables or disables caching.
Set	entrySet()
boolean	equals(Object o)
Object	get(Object key) This method retrieves the specified object, if it is not in the cacheit will be fetched from the data store.
CachePolicy	getCachePolicy() This method gets the CachePolicy object for this Cache
Object	getFromPersistentMap(Object key) This method bypasses the memory cache and will get the object from the underlying data store
String	getName() Returns the name.
Map	getPersistentMap()
int	hashCode()
boolean	isEmpty()
Set	keySet() This method gets all the keys in the cache
Object	put(Object key, Object value) This method updates the specified object to the data-store.
void	putAll(Map values) This method places the specified values in the cache and the data-store.
Object	remove(Object key) This method removes the specified object from the cache and the data store.
void	remove(Set keySet) This method removes the specified keys from the cache and the data store.
void	removeAll() Removes all objects from the cache and from the data store.
void	removeCacheListener(Object key, CacheListener listener) Removes a CacheListener for a specified key.
void	setCachePolicy(CachePolicy policy) This method sets the CachePolicy object for this Cache
void	setName(String name) Returns the value.
void	setPersistentMap(Map map)
int	size()
String	toString() This method converts the cache to a String representation
Collection	values() see java.util.Map

Methods inherited from class java.lang.Object

getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

GenericCache

public GenericCache()

Default Constructor

GenericCache

public GenericCache(CachePolicy policy)

Constructor

Parameters:

policy - The caching policy to use for this cache

GenericCache

public GenericCache(Map persistentMap)

Constructor

Parameters:

persistentMap - Map instance that persists data in the cache to the data store

GenericCache

public GenericCache(Map persistentMap,
                    CachePolicy policy)

Constructor

Parameters:

persistentMap - Map instance that persists data in the cache to the data store

policy - Policy object defining behaviour for removing objects from cache

Method Detail

cleanup

public void cleanup()

This method cleans up the cache by removing un-needed entries

Specified by:

cleanup in interface Cache

clear

public void clear()

This method clears the cache. Does not remove entries from the persistent map

Specified by:

clear in interface Map

containsKey

public boolean containsKey(Object key)

Specified by:

containsKey in interface Map

See Also:

Invokes this.get(Object key) and checks if value returned is null. This will ensure that if an entry exists and a cache policy is used, the entry timeout will be updated so it is available for use again.

containsValue

public boolean containsValue(Object value)

Specified by:

containsValue in interface Map

See Also:

Note that the cache may contain the value, but the key may have expired and is due to be removed. This means that the cache may not have the value the next time this method is called.

enableCaching

public void enableCaching(boolean enableCache)

This method enables or disables caching. When caching is disabled the cache passes all operations on to the persistent map instance.

Specified by:

enableCaching in interface Cache

Parameters:

enableCache - true to enable, false to disable

entrySet

public Set entrySet()

Specified by:

entrySet in interface Map

See Also:

Map

equals

public boolean equals(Object o)

Specified by:

equals in interface Map

Overrides:

equals in class Object

See Also:

Map

get

public Object get(Object key)

This method retrieves the specified object, if it is not in the cacheit will be fetched from the data store.

Specified by:

get in interface Map

Parameters:

key - Unique key identifying the object

Returns:

Instance of the object

getCachePolicy

public CachePolicy getCachePolicy()

This method gets the CachePolicy object for this Cache

Specified by:

getCachePolicy in interface Cache

Returns:

CachePolicy instance or null if there is no CachePolicy

getFromPersistentMap

public Object getFromPersistentMap(Object key)

This method bypasses the memory cache and will get the object from the underlying data store

Parameters:

key - Unique key identifying the object

Returns:

Instance of the object

hashCode

public int hashCode()

Specified by:

hashCode in interface Map

Overrides:

hashCode in class Object

See Also:

Map

isEmpty

public boolean isEmpty()

Specified by:

isEmpty in interface Map

See Also:

Map

keySet

public Set keySet()

This method gets all the keys in the cache

Specified by:

keySet in interface Map

put

public Object put(Object key,
                  Object value)

This method updates the specified object to the data-store. It also updates the reference stored in the cache. If the object does not exist in the data-store it will be created.

Specified by:

put in interface Map

Parameters:

key - Unique key identifying the object

value - The object

putAll

public void putAll(Map values)

This method places the specified values in the cache and the data-store. :param values a map of values to add to the cache.

Specified by:

putAll in interface Map

remove

public Object remove(Object key)

This method removes the specified object from the cache and the data store.

Specified by:

remove in interface Map

Parameters:

key - Unique key identifying the object to remove

remove

public void remove(Set keySet)

This method removes the specified keys from the cache and the data store.

Specified by:

remove in interface Cache

Parameters:

keySet - the set of keys to remove

removeAll

public void removeAll()

Removes all objects from the cache and from the data store. Use this method with caution!

Specified by:

removeAll in interface Cache

setCachePolicy

public void setCachePolicy(CachePolicy policy)

This method sets the CachePolicy object for this Cache

Specified by:

setCachePolicy in interface Cache

Parameters:

policy - The new cache policy

size

public int size()

Specified by:

size in interface Map

See Also:

Map

toString

public String toString()

This method converts the cache to a String representation

Overrides:

toString in class Object

Returns:

a string representation

values

public Collection values()

see java.util.Map

Specified by:

values in interface Map

getPersistentMap

public Map getPersistentMap()

Returns:

Map

setPersistentMap

public void setPersistentMap(Map map)

Specified by:

setPersistentMap in interface PersistentCache

Parameters:

map -

getName

public String getName()

Description copied from interface: NamedCache

Returns the name.

Specified by:

getName in interface NamedCache

Returns:

String

See Also:

NamedCache.getName()

setName

public void setName(String name)

Description copied from interface: NamedCache

Returns the value.

Specified by:

setName in interface NamedCache

Parameters:

name - String

See Also:

NamedCache.setName(String)

addCacheListener

public void addCacheListener(Object key,
                             CacheListener listener)

Adds a CacheListener for a specified key. Listeners will be notified of actions on the cache for that key only.

Specified by:

addCacheListener in interface Cache

removeCacheListener

public void removeCacheListener(Object key,
                                CacheListener listener)

Removes a CacheListener for a specified key.

Specified by:

removeCacheListener in interface Cache