Commons Collections LRU算法

LRU从容器中获取一个对象

    public Object get(Object key) {
        LinkEntry entry = (LinkEntry) getEntry(key);
        if (entry == null) {
            return null;
        }
        moveToMRU(entry);
        return entry.getValue();
    }

moveToMRU记录每次访问,++
并且移动

    //-----------------------------------------------------------------------
    /**
     * Moves an entry to the MRU position at the end of the list.
     * <p>
     * This implementation moves the updated entry to the end of the list.
     * 
     * @param entry  the entry to update
     */
    protected void moveToMRU(LinkEntry entry) {
        if (entry.after != header) {
            modCount++;
            // remove
            entry.before.after = entry.after;
            entry.after.before = entry.before;
            // add first
            entry.after = header;
            entry.before = header.before;
            header.before.after = entry;
            header.before = entry;
        } else if (entry == header) {
            throw new IllegalStateException("Can't move header to MRU" +
                " (please report this to [e-mail])");
        }
    }