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Java > Open Source Codes > com > jcorporate > expresso > core > cache > Cache


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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 JavaDoc;
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 JavaDoc 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 JavaDoc 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 JavaDoc 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 JavaDoc 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 JavaDoc 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 JavaDoc 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 JavaDoc newName);
205
206 }
207
208
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