Package com.gentlyweb.utils

Class ObjectCache

java.lang.Object

com.gentlyweb.utils.ObjectCache

All Implemented Interfaces:

ObjectCacheManager

public class ObjectCache
extends Object
implements ObjectCacheManager

The ObjectCache is it's own manager which means that classes that extend this one can do so quickly and without having to implement the ObjectCacheManager interface they only have to provide their own functionality whilst client classes can rely on the interface. All operations defined with ObjectCacheManager are supported here.

Field Summary

Fields

Modifier and Type	Field	Description
static int	OLDEST
static int	RANDOM
static int	YOUNGEST

Constructor Summary

Constructors

Constructor	Description
ObjectCache(int policy)

Method Summary

Modifier and Type	Method	Description
ObjectCache	cacheSlice(Date from, Date to)
ObjectCache	cacheSliceFrom(Date from)
ObjectCache	cacheSliceTo(Date to)
int	capacity()	Return the current capacity of the cache, it should basically be (max size - current size).
boolean	containsKey(Object key)
Object	firstKey()
Object	firstValue()
void	flush()	Clear our data structures.
Object	get(Object key)
Date	getLastAccessTime(Object key)
int	getMaxSize()
int	getPolicy()
boolean	isEmpty()	Return whether the cache is empty or not.
Iterator	iterator()
List	keys()	Return a List of all the keys in the cache.
List	keys(GeneralFilter f)	Return a List of all the keys in the cache that match the conditions imposed by the GeneralFilter passed in.
List	keysForFilteredValues(GeneralFilter f)	Return a List of keys in the cache that match the conditions imposed by the GeneralFilter AND are applied to the values NOT the keys.
void	keysToList(List list)
Object	lastValue()
void	merge(ObjectCache cache)	Merge the current cache with another.
void	put(Object key, Object value)
void	putAll(Map map)	Add all the entries in the Map to cache.
void	remove(Object key)
protected void	resize()
void	resize(int size)	Resize the cache to a particular size, if the size is actually bigger than the current size then this operation should not touch the cached objects, if the size is less then the cache should be reduced in size using the current policy until the size is reached.
void	setMaxSize(int size)	Set the maximum size of the cache.
void	setPolicy(int type)	Set the policy for managing the cache, should be one of: ObjectCache.OLDEST, ObjectCache.YOUNGEST, ObjectCache.RANDOM.
int	size()
Map	slice(Date from, Date to)
Map	sliceFrom(Date from)
Map	sliceTo(Date to)
void	toMap(Map map)	Get all the entries in the cache as a Map of key to value.
List	values()	Return a List of all the values in the cache.
List	values(GeneralFilter f)	Return a List of all the values in the cache that match the conditions imposed by the GeneralFilter passed in.
void	valuesToList(List list)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

OLDEST

public static final int OLDEST

See Also:

Constant Field Values

YOUNGEST

public static final int YOUNGEST

See Also:

Constant Field Values

RANDOM

public static final int RANDOM

See Also:

Constant Field Values

Constructor Detail

ObjectCache

public ObjectCache(int policy)
            throws IllegalArgumentException

Throws:

IllegalArgumentException

Method Detail

setPolicy

public void setPolicy(int type)
               throws IllegalArgumentException

Description copied from interface: ObjectCacheManager

Set the policy for managing the cache, should be one of: ObjectCache.OLDEST, ObjectCache.YOUNGEST, ObjectCache.RANDOM.

Specified by:

setPolicy in interface ObjectCacheManager

Parameters:

type - The policy.

Throws:

IllegalArgumentException

getPolicy

public int getPolicy()

iterator

public Iterator iterator()

keys

public List keys()

Return a List of all the keys in the cache.

Returns:

The List (ArrayList) of all the keys in the cache.

values

public List values()

Return a List of all the values in the cache.

Returns:

The List (ArrayList) of all the values in the cache.

keysForFilteredValues

public List keysForFilteredValues(GeneralFilter f)
                           throws IllegalAccessException,
                                  InvocationTargetException,
                                  FilterException

Return a List of keys in the cache that match the conditions imposed by the GeneralFilter AND are applied to the values NOT the keys.

Parameters:

f - The filter to use.

Returns:

A List of the keys that map to the matched values.

Throws:

IllegalAccessException - Thrown by the {@link GeneralFilter.accept(Object)} method if we can't get access to a value defined in the GeneralFilter for the value class.

InvocationTargetException - Thrown by the {@link GeneralFilter.accept(Object)} method if (as a result of accessing a field) an exception is thrown by a value object.

FilterException - Thrown by the {@link GeneralFilter.accept(Object)} method if (as a result of accessing a field) the type of object returned by the field access is not of the expected type.

values

public List values(GeneralFilter f)
            throws IllegalAccessException,
                   InvocationTargetException,
                   FilterException

Return a List of all the values in the cache that match the conditions imposed by the GeneralFilter passed in. We first gain all the values in the cache and then pass them through the filter returning the values that match. Because a GeneralFilter can only filter on a single class type (but the values may not be of a single type) we ignore any values that are not of the type specified for the GeneralFilter.

Returns:

A List (ArrayList) of all the values in the cache.

Throws:

IllegalAccessException - Thrown by the {@link GeneralFilter.accept(Object)} method if we can't get access to a value defined in the GeneralFilter for the value class.

InvocationTargetException - Thrown by the {@link GeneralFilter.accept(Object)} method if (as a result of accessing a field) an exception is thrown by a value object.

FilterException - Thrown by the {@link GeneralFilter.accept(Object)} method if (as a result of accessing a field) the type of object returned by the field access is not of the expected type.

keys

public List keys(GeneralFilter f)
          throws IllegalAccessException,
                 InvocationTargetException,
                 FilterException

Return a List of all the keys in the cache that match the conditions imposed by the GeneralFilter passed in. We first gain all the keys in the cache and then pass them through the filter returning the keys that match. Because a GeneralFilter can only filter on a single class type (but the keys may not be of a single type) we ignore any keys that are not of the type specified for the GeneralFilter.

Returns:

A List (ArrayList) of all the keys in the cache.

Throws:

IllegalAccessException - Thrown by the {@link GeneralFilter.accept(Object)} method if we can't get access to a value defined in the GeneralFilter for the key class.

InvocationTargetException - Thrown by the {@link GeneralFilter.accept(Object)} method if (as a result of accessing a field) an exception is thrown by a key object.

FilterException - Thrown by the {@link GeneralFilter.accept(Object)} method if (as a result of accessing a field) the type of object returned by the field access is not of the expected type.

valuesToList

public void valuesToList(List list)

keysToList

public void keysToList(List list)

toMap

public void toMap(Map map)

Description copied from interface: ObjectCacheManager

Get all the entries in the cache as a Map of key to value.

Specified by:

toMap in interface ObjectCacheManager

Parameters:

map - The Map that should be populated with the key/values in the cache.

putAll

public void putAll(Map map)

Description copied from interface: ObjectCacheManager

Add all the entries in the Map to cache.

Specified by:

putAll in interface ObjectCacheManager

Parameters:

map - The Map to get key/values from.

containsKey

public boolean containsKey(Object key)

merge

public void merge(ObjectCache cache)

Description copied from interface: ObjectCacheManager

Merge the current cache with another.

Specified by:

merge in interface ObjectCacheManager

Parameters:

cache - The cache to merge.

cacheSliceTo

public ObjectCache cacheSliceTo(Date to)

cacheSliceFrom

public ObjectCache cacheSliceFrom(Date from)

cacheSlice

public ObjectCache cacheSlice(Date from,
                              Date to)

sliceFrom

public Map sliceFrom(Date from)

sliceTo

public Map sliceTo(Date to)

slice

public Map slice(Date from,
                 Date to)

getLastAccessTime

public Date getLastAccessTime(Object key)

isEmpty

public boolean isEmpty()

Description copied from interface: ObjectCacheManager

Return whether the cache is empty or not.

Specified by:

isEmpty in interface ObjectCacheManager

Returns:

true if the cache is empty, false if it has entries.

capacity

public int capacity()

Description copied from interface: ObjectCacheManager

Return the current capacity of the cache, it should basically be (max size - current size).

Specified by:

capacity in interface ObjectCacheManager

Returns:

The current number of items that can be added until the cache reaches it's maximum size.

getMaxSize

public int getMaxSize()

setMaxSize

public void setMaxSize(int size)

Description copied from interface: ObjectCacheManager

Set the maximum size of the cache.

Specified by:

setMaxSize in interface ObjectCacheManager

Parameters:

size - The maximum size.

get

public Object get(Object key)

firstValue

public Object firstValue()

lastValue

public Object lastValue()

firstKey

public Object firstKey()

size

public int size()

remove

public void remove(Object key)

resize

public void resize(int size)

Description copied from interface: ObjectCacheManager

Resize the cache to a particular size, if the size is actually bigger than the current size then this operation should not touch the cached objects, if the size is less then the cache should be reduced in size using the current policy until the size is reached. Either way the maximum size should be set to this value.

Specified by:

resize in interface ObjectCacheManager

Parameters:

size - The new size.

resize

protected void resize()

put

public void put(Object key,
                Object value)

flush

public void flush()

Clear our data structures.

Specified by:

flush in interface ObjectCacheManager