Cache


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2    * The Jcorporate Apache Style Software License, Version 1.2 05-07-2002
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64  
65  package com.jcorporate.expresso.core.cache;
66  
67  /**
68   * Cache.java
69   *
70   * Copyright 1999, 2000, 2001 Jcorporate Ltd.
71   */
72  
73  import java.util.Vector  ;
74  
75  
76  /**
77   * A cache is a list of Cacheable objects that can be stored in memory,
78   * cleared, added to and removed from. It also
79   * stores information about how many times it has been used.
80   * This interface defines how a generic cache object should behave,
81   * but the specifics are up to the
82   * implementor.
83   * <p>Implementation Note:  The implementation of ordered or unordered caches
84   * should be such that getItems() or getItem() will NEVER return an expired
85   * cache item.  Implementations should check isExpired() before adding the
86   * cache item to the return list.
87   * </p>
88   */
89  public interface Cache {
90      /**
91       * Add a new item to the cache.
92       *
93       * @param newItem the new item to add to the cache
94       */
95      void addItem(CacheEntry newItem);
96  
97      /**
98       * Clear all items from the cache
99       */
100     void clear();
101 
102 
103     /**
104      * Retrieve the low-level CacheEntry for the cache.  This is particularly
105      * useful for debugging or management.
106      *
107      * @param itemKey the key for the entry
108      * @return a CacheEntry object or null if it doesn't exist
109      */
110     CacheEntry getCacheEntry(String   itemKey);
111 
112     /**
113      * Get the item indicated by the given key from the cache.
114      * All Cacheable items define a getKey()
115      * method that defines how the item is differentated from other items in the cache
116      *
117      * @param itemKey the key of the item to retrieve
118      * @return the Object stored in the cache.
119      */
120     Cacheable getItem(String   itemKey);
121 
122 
123     /**
124      * Retrieve whether the cache instance is an ordered cache [list based]
125      * or unordered cache. [map based]
126      *
127      * @return true if the cache is an ordered cache.
128      */
129     boolean isOrdered();
130 
131     /**
132      * Retrieve Cache Item Count
133      *
134      * @return The number of items in the cache
135      */
136     int getItemCount();
137 
138 
139     /**
140      * Get all the items in the cache
141      *
142      * @return java.util.Vector - The items in the cache
143      */
144     Vector   getItems();
145 
146 
147     /**
148      * Get the name of the cache
149      *
150      * @return java.lang.String the name of the cache.
151      */
152     String   getName();
153 
154 
155     /**
156      * Get how many times this cache has been used
157      *
158      * @return long
159      */
160     long getUsedCount();
161 
162 
163     /**
164      * Removes the specified item from the cache.
165      *
166      * @param itemKey The item in the cache to remove
167      */
168     void removeItem(Cacheable itemKey);
169 
170 
171     /**
172      * Set the items in the cache
173      *
174      * @param newItems The vector of new items
175      * @throws CacheException If there's an error setting the new items in
176      *                        the cache
177      */
178     void setItems(Vector   newItems)
179             throws CacheException;
180 
181 
182     /**
183      * Eventually the new way to set items
184      *
185      * @param newItems the new items to add
186      * @throws CacheException upon error
187      */
188     void setItems(java.util.List   newItems) throws CacheException;
189 
190 
191     /**
192      * Sets the maximum size of the cache
193      *
194      * @param newMax The new maximum size of the cache.
195      */
196     void setMaxSize(int newMax);
197 
198 
199     /**
200      * Sets the name of the cache
201      *
202      * @param newName java.lang.String The new name of the cache.
203      */
204     void setName(String   newName);
205 
206 }
207 
208
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