使用LinkedHashMap构建LRU的Cache

使用LinkedHashMap构建LRU的Cache

 

package tags;import java.util.LinkedHashMap;public class LRUCache<K,V> extends LinkedHashMap<K,V> {    /** 最大数据存储容量 */      private static final int  LRU_MAX_CAPACITY     = 1024;      /** 存储数据容量  */      private int               capacity;      public LRUCache() {          super();      }      public LRUCache(int initialCapacity, float loadFactor,Boolean useCache) {          super(initialCapacity, loadFactor, useCache);          capacity = LRU_MAX_CAPACITY;      }       public LRUCache(int initialCapacity, float loadFactor,Boolean useCache, int lruCapacity) {          super(initialCapacity, loadFactor, true);          this.capacity = lruCapacity;      }      @Override     protected boolean removeEldestEntry(Map.Entry<K,V> eldest) {        System.out.println(eldest.getKey() + "=" + eldest.getValue());          return size () > LRUCache.this.capacity;    }              public static void main(String[] args) {            LRUCache<String, String> map = new LRUCache<String, String>(16, 0.75f,true);          map.put("a", "a"); //a  a          map.put("b", "b"); //a  a b          map.put("c", "c"); //a  a b c          map.put("a", "a2"); //   b c a               map.put("d", "d"); //b  b c a d          map.put("a", "a3"); //   b c d a          map.put("b", "b2"); //   c d a b               map.put("f", "f"); //c  c d a b f          map.put("g", "g"); //c  c d a b f g                map.get("d"); //c a b f g d          for (Entry<String, String> entry : map.entrySet()) {              System.out.print(entry.getValue() + ", ");          }          System.out.println();                /*map.get("a"); //c b f g d a          for (Entry<String, String> entry : map.entrySet()) {              System.out.print(entry.getValue() + ", ");          }          System.out.println();                map.get("c"); //b f g d a c          for (Entry<String, String> entry : map.entrySet()) {              System.out.print(entry.getValue() + ", ");          }          System.out.println();                map.get("b"); //f g d a c b          for (Entry<String, String> entry : map.entrySet()) {              System.out.print(entry.getValue() + ", ");          }          System.out.println();                map.put("h", "h"); //f  f g d a c b h          for (Entry<String, String> entry : map.entrySet()) {              System.out.print(entry.getValue() + ", ");          }          System.out.println();  */    }}

 

结果：

 

a=a

a=a

a=a

b=b

c=c

c=c

c, a3, b2, f, g, d, 

c, b2, f, g, d, a3, 

b2, f, g, d, a3, c, 

f, g, d, a3, c, b2, 

f=f

f, g, d, a3, c, b2, h,

 

LinkedHashMap : http://uule.iteye.com/admin/blogs/1522291