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javatools.util
Class Cache  

java.lang.Object
  javatools.util.Cache

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public class Cache

extends java.lang.Object

General purpose cache class. Acts basically like a weak reference dictionary except that it also returns null when asked to find an item whose use-by date has expired. It works with two main data structures: A Dictionary which provides fast access into the cache, and a Queue which keeps track of the least recently used items in the cache so that old items can be removed and limit the cache to a bounded size. Modified: 8th March 2003 11:41

Version:

0.1.10

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Nested Class Summary
(package private)  class	Cache.CacheItem           This is the class we store in our internal data structures.

 

Field Summary
private  int	cacheMaxAge           The maximum age of items in the cache in milliseconds.
private  int	cacheMaxObj           The maximum number of objects in the cache
private  java.util.Dictionary	dictionary           The fast access dictionary
private  JQueue	queue           The lru (least recently used) queue

 

Constructor Summary

Cache()           Creates a new Cache object.

Cache(int size)           Constructor which takes an initial guesstimate of how many items we expect to store in it

 

Method Summary
void	clear()
void	expire(java.lang.Object key)           Expire the item in the cache with the given key.
java.lang.Object	get(java.lang.Object key)           Get an object from the cache.
void	put(java.lang.Object key, java.lang.Object item)           Put a key value pair into the cache.
void	setCacheMaxAgeSeconds(int s)           Change the maximum age of items in the cache.
void	setCacheMaxObj(int n)           Set the maximum number of objects to cache.
void	setNoCacheMaxAge()           Turn off cache expiry based on age

 

Methods inherited from class java.lang.Object

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

 

Field Detail

dictionary

private java.util.Dictionary dictionary

The fast access dictionary

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queue

private JQueue queue

The lru (least recently used) queue

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cacheMaxObj

private int cacheMaxObj

The maximum number of objects in the cache

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cacheMaxAge

private int cacheMaxAge

The maximum age of items in the cache in milliseconds.

Constructor Detail

Cache

public Cache()

Creates a new Cache object.

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Cache

public Cache(int size)

Constructor which takes an initial guesstimate of how many items we expect to store in it

Method Detail

setCacheMaxObj

public void setCacheMaxObj(int n)

Set the maximum number of objects to cache.

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setCacheMaxAgeSeconds

public void setCacheMaxAgeSeconds(int s)

Change the maximum age of items in the cache. Can be changed at any time.

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setNoCacheMaxAge

public void setNoCacheMaxAge()

Turn off cache expiry based on age

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get

public java.lang.Object get(java.lang.Object key)

Get an object from the cache. Returns null if the object is not in the cache.

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put

public void put(java.lang.Object key,
                java.lang.Object item)

Put a key value pair into the cache.

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expire

public void expire(java.lang.Object key)

Expire the item in the cache with the given key.

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clear

public void clear()

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