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CachingMapDecorator (Spring Framework API 2.1) - Spring Framework 2.1.0 API 文档英文版

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org.springframework.util
Class CachingMapDecorator

java.lang.Object
  org.springframework.util.CachingMapDecorator

All Implemented Interfaces:

Serializable, Map

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public abstract class CachingMapDecorator
extends Object
implements Map, Serializable

A simple decorator for a Map, encapsulating the workflow for caching expensive values in a target Map. Supports caching weak or strong keys.

This class is also an abstract template. Caching Map implementations should subclass and override the create(key) method which encapsulates expensive creation of a new object.

Since:

1.2.2

Author:

Keith Donald

See Also:

Serialized Form

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Nested Class Summary

 

Nested classes/interfaces inherited from interface java.util.Map
Map.Entry<K,V>

 

Constructor Summary
CachingMapDecorator()           Create a CachingMapDecorator with strong keys, using an underlying synchronized Map.
CachingMapDecorator(boolean weakKeys)           Create a CachingMapDecorator, using an underlying synchronized Map.
CachingMapDecorator(boolean weakKeys, int size)           Create a CachingMapDecorator with initial size, using an underlying synchronized Map.
CachingMapDecorator(Map targetMap)           Create a CachingMapDecorator for the given Map.

 

Method Summary
void	clear()
boolean	containsKey(Object key)
boolean	containsValue(Object value)
protected abstract  Object	create(Object key)           Create a value to cache for the given key.
Set	entrySet()
Object	get(Object key)           Get value for key.
boolean	isEmpty()
Set	keySet()
Object	put(Object key, Object value)
void	putAll(Map t)
Object	remove(Object key)
int	size()
String	toString()
Collection	values()

 

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

 

Methods inherited from interface java.util.Map
equals, hashCode

 

Constructor Detail

CachingMapDecorator

public CachingMapDecorator()

Create a CachingMapDecorator with strong keys, using an underlying synchronized Map.

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CachingMapDecorator

public CachingMapDecorator(boolean weakKeys)

Create a CachingMapDecorator, using an underlying synchronized Map.

Parameters:

weakKeys - whether to use weak references for keys

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CachingMapDecorator

public CachingMapDecorator(boolean weakKeys,
                           int size)

Create a CachingMapDecorator with initial size, using an underlying synchronized Map.

Parameters:

weakKeys - whether to use weak references for keys

size - the initial cache size

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CachingMapDecorator

public CachingMapDecorator(Map targetMap)

Create a CachingMapDecorator for the given Map.

The passed-in Map won't get synchronized explicitly, so make sure to pass in a properly synchronized Map, if desired.

Parameters:

targetMap - the Map to decorate

Method Detail

size

public int size()

Specified by:

size in interface Map

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isEmpty

public boolean isEmpty()

Specified by:

isEmpty in interface Map

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containsKey

public boolean containsKey(Object key)

Specified by:

containsKey in interface Map

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containsValue

public boolean containsValue(Object value)

Specified by:

containsValue in interface Map

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put

public Object put(Object key,
                  Object value)

Specified by:

put in interface Map

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remove

public Object remove(Object key)

Specified by:

remove in interface Map

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putAll

public void putAll(Map t)

Specified by:

putAll in interface Map

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clear

public void clear()

Specified by:

clear in interface Map

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keySet

public Set keySet()

Specified by:

keySet in interface Map

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values

public Collection values()

Specified by:

values in interface Map

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entrySet

public Set entrySet()

Specified by:

entrySet in interface Map

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get

public Object get(Object key)

Get value for key. Creates and caches value if it doesn't already exist in the cache.

This implementation is not synchronized: This is highly concurrent but does not guarantee unique instances in the cache, as multiple values for the same key could get created in parallel. Consider overriding this method to synchronize it, if desired.

Specified by:

get in interface Map

See Also:

create(Object)

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create

protected abstract Object create(Object key)

Create a value to cache for the given key. Called by get if there is no value cached already.

Parameters:

key - the cache key

See Also:

get(Object)

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toString

public String toString()

Overrides:

toString in class Object

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