compositemap.java

JAVA 文章管理系统源码

     */
    public Object get(Object key) {
        for (int i = this.composite.length - 1; i >= 0; --i) {
            if (this.composite[i].containsKey(key)) {
                return this.composite[i].get(key);
            }
        }
        return null;
    }
    
    /**
     * Returns <tt>true</tt> if this map contains no key-value mappings.
     *
     * @return <tt>true</tt> if this map contains no key-value mappings.
     */
    public boolean isEmpty() {
        for (int i = this.composite.length - 1; i >= 0; --i) {
            if (!this.composite[i].isEmpty()) {
                return false;
            }
        }
        return true;
    }
    
    /**
     * Returns a set view of the keys contained in this map.  The set is
     * backed by the map, so changes to the map are reflected in the set, and
     * vice-versa.  If the map is modified while an iteration over the set is
     * in progress, the results of the iteration are undefined.  The set
     * supports element removal, which removes the corresponding mapping from
     * the map, via the <tt>Iterator.remove</tt>, <tt>Set.remove</tt>,
     * <tt>removeAll</tt> <tt>retainAll</tt>, and <tt>clear</tt> operations.
     * It does not support the add or <tt>addAll</tt> operations.
     * <p>
     * This implementation returns a <code>CompositeSet</code> which
     * composites the key sets from all of the composited maps.
     *
     * @return a set view of the keys contained in this map.
     */
    public Set keySet() {
        CompositeSet keys = new CompositeSet();
        for (int i = this.composite.length - 1; i >= 0; --i) {
            keys.addComposited(this.composite[i].keySet());
        }
        return keys;
    }
    
    /**
     * Associates the specified value with the specified key in this map
     * (optional operation).  If the map previously contained a mapping for
     * this key, the old value is replaced by the specified value.  (A map
     * <tt>m</tt> is said to contain a mapping for a key <tt>k</tt> if and only
     * if {@link #containsKey(Object) m.containsKey(k)} would return
     * <tt>true</tt>.))
     *
     * @param key key with which the specified value is to be associated.
     * @param value value to be associated with the specified key.
     * @return previous value associated with specified key, or <tt>null</tt>
     *	       if there was no mapping for key.  A <tt>null</tt> return can
     *	       also indicate that the map previously associated <tt>null</tt>
     *	       with the specified key, if the implementation supports
     *	       <tt>null</tt> values.
     *
     * @throws UnsupportedOperationException if no MapMutator has been specified
     * @throws ClassCastException if the class of the specified key or value
     * 	          prevents it from being stored in this map.
     * @throws IllegalArgumentException if some aspect of this key or value
     *	          prevents it from being stored in this map.
     * @throws NullPointerException this map does not permit <tt>null</tt>
     *            keys or values, and the specified key or value is
     *            <tt>null</tt>.
     */
    public Object put(Object key, Object value) {
        if (this.mutator == null) {
            throw new UnsupportedOperationException("No mutator specified");
        }
        return this.mutator.put(this, this.composite, key, value);
    }
    
    /**
     * Copies all of the mappings from the specified map to this map
     * (optional operation).  The effect of this call is equivalent to that
     * of calling {@link #put(Object,Object) put(k, v)} on this map once
     * for each mapping from key <tt>k</tt> to value <tt>v</tt> in the
     * specified map.  The behavior of this operation is unspecified if the
     * specified map is modified while the operation is in progress.
     *
     * @param map Mappings to be stored in this map.
     *
     * @throws UnsupportedOperationException if the <tt>putAll</tt> method is
     * 		  not supported by this map.
     *
     * @throws ClassCastException if the class of a key or value in the
     * 	          specified map prevents it from being stored in this map.
     *
     * @throws IllegalArgumentException some aspect of a key or value in the
     *	          specified map prevents it from being stored in this map.
     * @throws NullPointerException the specified map is <tt>null</tt>, or if
     *         this map does not permit <tt>null</tt> keys or values, and the
     *         specified map contains <tt>null</tt> keys or values.
     */
    public void putAll(Map map) {
        if (this.mutator == null) {
            throw new UnsupportedOperationException("No mutator specified");
        }
        this.mutator.putAll(this, this.composite, map);
    }
    
    /**
     * Removes the mapping for this key from this map if it is present
     * (optional operation).   More formally, if this map contains a mapping
     * from key <tt>k</tt> to value <tt>v</tt> such that
     * <code>(key==null ?  k==null : key.equals(k))</code>, that mapping
     * is removed.  (The map can contain at most one such mapping.)
     *
     * <p>Returns the value to which the map previously associated the key, or
     * <tt>null</tt> if the map contained no mapping for this key.  (A
     * <tt>null</tt> return can also indicate that the map previously
     * associated <tt>null</tt> with the specified key if the implementation
     * supports <tt>null</tt> values.)  The map will not contain a mapping for
     * the specified  key once the call returns.
     *
     * @param key key whose mapping is to be removed from the map.
     * @return previous value associated with specified key, or <tt>null</tt>
     *	       if there was no mapping for key.
     *
     * @throws ClassCastException if the key is of an inappropriate type for
     * 		  the composited map (optional).
     * @throws NullPointerException if the key is <tt>null</tt> and the composited map
     *            does not not permit <tt>null</tt> keys (optional).
     * @throws UnsupportedOperationException if the <tt>remove</tt> method is
     *         not supported by the composited map containing the key
     */
    public Object remove(Object key) {
        for (int i = this.composite.length - 1; i >= 0; --i) {
            if (this.composite[i].containsKey(key)) {
                return this.composite[i].remove(key);
            }
        }
        return null;
    }
    
    /**
     * Returns the number of key-value mappings in this map.  If the
     * map contains more than <tt>Integer.MAX_VALUE</tt> elements, returns
     * <tt>Integer.MAX_VALUE</tt>.
     *
     * @return the number of key-value mappings in this map.
     */
    public int size() {
        int size = 0;
        for (int i = this.composite.length - 1; i >= 0; --i) {
            size += this.composite[i].size();
        }
        return size;
    }
    
    /**
     * Returns a collection view of the values contained in this map.  The
     * collection is backed by the map, so changes to the map are reflected in
     * the collection, and vice-versa.  If the map is modified while an
     * iteration over the collection is in progress, the results of the
     * iteration are undefined.  The collection supports element removal,
     * which removes the corresponding mapping from the map, via the
     * <tt>Iterator.remove</tt>, <tt>Collection.remove</tt>,
     * <tt>removeAll</tt>, <tt>retainAll</tt> and <tt>clear</tt> operations.
     * It does not support the add or <tt>addAll</tt> operations.
     *
     * @return a collection view of the values contained in this map.
     */
    public Collection values() {
        CompositeCollection keys = new CompositeCollection();
        for (int i = this.composite.length - 1; i >= 0; --i) {
            keys.addComposited(this.composite[i].values());
        }
        return keys;
    }
    
    /**
     * Checks if this Map equals another as per the Map specification.
     * 
     * @param obj  the object to compare to
     * @return true if the maps are equal
     */
    public boolean equals(Object obj) {
        if (obj instanceof Map) {
            Map map = (Map) obj;
            return (this.entrySet().equals(map.entrySet()));
        }
        return false;
    }
    
    /**
     * Gets a hash code for the Map as per the Map specification.
     */
    public int hashCode() {
        int code = 0;
        for (Iterator i = this.entrySet().iterator(); i.hasNext();) {
            code += i.next().hashCode();
        }
        return code;
    }
    
    /**
     * This interface allows definition for all of the indeterminate
     * mutators in a CompositeMap, as well as providing a hook for
     * callbacks on key collisions.
     */
    public static interface MapMutator {
        /**
         * Called when adding a new Composited Map results in a
         * key collision.
         *
         * @param composite  the CompositeMap with the collision
         * @param existing  the Map already in the composite which contains the
         *        offending key
         * @param added  the Map being added
         * @param intersect  the intersection of the keysets of the existing and added maps
         */
        public void resolveCollision(
            CompositeMap composite, Map existing, Map added, Collection intersect);
        
        /**
         * Called when the CompositeMap.put() method is invoked.
         *
         * @param map  the CompositeMap which is being modified
         * @param composited  array of Maps in the CompositeMap being modified
         * @param key  key with which the specified value is to be associated.
         * @param value  value to be associated with the specified key.
         * @return previous value associated with specified key, or <tt>null</tt>
         *	       if there was no mapping for key.  A <tt>null</tt> return can
         *	       also indicate that the map previously associated <tt>null</tt>
         *	       with the specified key, if the implementation supports
         *	       <tt>null</tt> values.
         *
         * @throws UnsupportedOperationException if not defined
         * @throws ClassCastException if the class of the specified key or value
         * 	          prevents it from being stored in this map.
         * @throws IllegalArgumentException if some aspect of this key or value
         *	          prevents it from being stored in this map.
         * @throws NullPointerException this map does not permit <tt>null</tt>
         *            keys or values, and the specified key or value is
         *            <tt>null</tt>.
         */
        public Object put(CompositeMap map, Map[] composited, Object key, Object value);
        
        /**
         * Called when the CompositeMap.putAll() method is invoked.
         *
         * @param map  the CompositeMap which is being modified
         * @param composited  array of Maps in the CompositeMap being modified
         * @param mapToAdd  Mappings to be stored in this CompositeMap
         *
         * @throws UnsupportedOperationException if not defined
         * @throws ClassCastException if the class of the specified key or value
         * 	          prevents it from being stored in this map.
         * @throws IllegalArgumentException if some aspect of this key or value
         *	          prevents it from being stored in this map.
         * @throws NullPointerException this map does not permit <tt>null</tt>
         *            keys or values, and the specified key or value is
         *            <tt>null</tt>.
         */
        public void putAll(CompositeMap map, Map[] composited, Map mapToAdd);
    }
}