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ExpiringCache.javaAPI DocJava SE 5 API2939Fri Aug 26 14:56:58 BST 2005java.io

ExpiringCache

public class ExpiringCache extends Object

Fields Summary
private long
millisUntilExpiration
private Map
map
private int
queryCount
private int
queryOverflow
private int
MAX_ENTRIES
Constructors Summary
ExpiringCache()

        this(30000);
ExpiringCache(long millisUntilExpiration)

        this.millisUntilExpiration = millisUntilExpiration;
        map = new LinkedHashMap() {
            protected boolean removeEldestEntry(Map.Entry eldest) {
              return size() > MAX_ENTRIES;
            }
          };
Methods Summary
private voidcleanup()

        Set keySet = map.keySet();
        // Avoid ConcurrentModificationExceptions
        String[] keys = new String[keySet.size()];
        int i = 0;
        for (Iterator iter = keySet.iterator(); iter.hasNext(); ) {
            String key = (String) iter.next();
            keys[i++] = key;
        }
        for (int j = 0; j < keys.length; j++) {
            entryFor(keys[j]);
        }
        queryCount = 0;
synchronized voidclear()

        map.clear();
private java.io.ExpiringCache$EntryentryFor(java.lang.String key)

        Entry entry = (Entry) map.get(key);
        if (entry != null) {
            long delta = System.currentTimeMillis() - entry.timestamp();
            if (delta < 0 || delta >= millisUntilExpiration) {
                map.remove(key);
                entry = null;
            }
        }
        return entry;
synchronized java.lang.Stringget(java.lang.String key)

        if (++queryCount >= queryOverflow) {
            cleanup();
        }
        Entry entry = entryFor(key);
        if (entry != null) {
            return entry.val();
        }
        return null;
synchronized voidput(java.lang.String key, java.lang.String val)

        if (++queryCount >= queryOverflow) {
            cleanup();
        }
        Entry entry = entryFor(key);
        if (entry != null) {
            entry.setTimestamp(System.currentTimeMillis());
            entry.setVal(val);
        } else {
            map.put(key, new Entry(System.currentTimeMillis(), val));
        }