lazydynamap.java

这是一个有关common beanutils 的源码

     * zero-length array will be returned.</p>
     *
     * <p><strong>FIXME</strong> - Should we really be implementing
     * <code>getBeanInfo()</code> instead, which returns property descriptors
     * and a bunch of other stuff?</p>
     * @return the set of properties for this DynaClass
     */
    public DynaProperty[] getDynaProperties() {

        int i = 0;
        DynaProperty[] properties = new DynaProperty[values.size()];
        Iterator iterator = values.keySet().iterator();

        while (iterator.hasNext()) {
            String name = (String)iterator.next();
            Object value = values.get(name);
            properties[i++] = new DynaProperty(name, value == null ? null : value.getClass());
        }

        return properties;

    }

    /**
     * Instantiate and return a new DynaBean instance, associated
     * with this DynaClass.
     * @return A new <code>DynaBean</code> instance
     */
    public DynaBean newInstance()  {

        // Create a new instance of the Map
        Map newMap = null;
        try {
            newMap = (Map)getMap().getClass().newInstance();
        } catch(Exception ex) {
            newMap = newMap();
        }

        // Crate new LazyDynaMap and initialize properties
        LazyDynaMap lazyMap = new LazyDynaMap(newMap);
        DynaProperty[] properties = this.getDynaProperties();
        if (properties != null) {
            for (int i = 0; i < properties.length; i++) {
                lazyMap.add(properties[i]);
            }
        }
        return lazyMap;
    }


    // ------------------- MutableDynaClass Methods ----------------------------------

    /**
     * <p>Is this DynaClass currently restricted.</p>
     * <p>If restricted, no changes to the existing registration of
     *  property names, data types, readability, or writeability are allowed.</p>
     *
     * @return <code>true</code> if this Mutable {@link DynaClass} is restricted,
     * otherwise <code>false</code>
     */
    public boolean isRestricted() {
        return restricted;
    }

    /**
     * <p>Set whether this DynaClass is currently restricted.</p>
     * <p>If restricted, no changes to the existing registration of
     *  property names, data types, readability, or writeability are allowed.</p>
     *
     * @param restricted The new restricted state
     */
    public void setRestricted(boolean restricted) {
        this.restricted = restricted;
    }

    /**
     * Add a new dynamic property with no restrictions on data type,
     * readability, or writeability.
     *
     * @param name Name of the new dynamic property
     *
     * @exception IllegalArgumentException if name is null
     */
    public void add(String name) {
        add(name, null);
    }

    /**
     * Add a new dynamic property with the specified data type, but with
     * no restrictions on readability or writeability.
     *
     * @param name Name of the new dynamic property
     * @param type Data type of the new dynamic property (null for no
     *  restrictions)
     *
     * @exception IllegalArgumentException if name is null
     * @exception IllegalStateException if this DynaClass is currently
     *  restricted, so no new properties can be added
     */
    public void add(String name, Class type) {

        if (name == null) {
            throw new IllegalArgumentException("Property name is missing.");
        }

        if (isRestricted()) {
            throw new IllegalStateException("DynaClass is currently restricted. No new properties can be added.");
        }

        Object value = values.get(name);

        // Check if the property already exists
        if (value == null) {
            values.put(name, type == null ? null : createProperty(name, type));
        }

    }

    /**
     * <p>Add a new dynamic property with the specified data type, readability,
     * and writeability.</p>
     *
     * <p><strong>N.B.</strong>Support for readable/writeable properties has not been implemented
     *    and this method always throws a <code>UnsupportedOperationException</code>.</p>
     *
     * <p>I'm not sure the intention of the original authors for this method, but it seems to
     *    me that readable/writable should be attributes of the <code>DynaProperty</code> class
     *    (which they are not) and is the reason this method has not been implemented.</p>
     *
     * @param name Name of the new dynamic property
     * @param type Data type of the new dynamic property (null for no
     *  restrictions)
     * @param readable Set to <code>true</code> if this property value
     *  should be readable
     * @param writeable Set to <code>true</code> if this property value
     *  should be writeable
     *
     * @exception UnsupportedOperationException anytime this method is called
     */
    public void add(String name, Class type, boolean readable, boolean writeable) {
        throw new java.lang.UnsupportedOperationException("readable/writable properties not supported");
    }

    /**
     * Add a new dynamic property.
     *
     * @param property Property the new dynamic property to add.
     *
     * @exception IllegalArgumentException if name is null
     */
    protected void add(DynaProperty property) {
        add(property.getName(), property.getType());
    }

    /**
     * Remove the specified dynamic property, and any associated data type,
     * readability, and writeability, from this dynamic class.
     * <strong>NOTE</strong> - This does <strong>NOT</strong> cause any
     * corresponding property values to be removed from DynaBean instances
     * associated with this DynaClass.
     *
     * @param name Name of the dynamic property to remove
     *
     * @exception IllegalArgumentException if name is null
     * @exception IllegalStateException if this DynaClass is currently
     *  restricted, so no properties can be removed
     */
    public void remove(String name) {

        if (name == null) {
            throw new IllegalArgumentException("Property name is missing.");
        }

        if (isRestricted()) {
            throw new IllegalStateException("DynaClass is currently restricted. No properties can be removed.");
        }

        // Remove, if property doesn't exist
        if (values.containsKey(name)) {
            values.remove(name);
        }

    }


    // ------------------- Additional Public Methods ----------------------------------

    /**
     * Should this DynaClass return a <code>null</code> from
     * the <code>getDynaProperty(name)</code> method if the property
     * doesn't exist.
     *
     * @return <code>true<code> if a <code>null</code> {@link DynaProperty}
     * should be returned if the property doesn't exist, otherwise
     * <code>false</code> if a new {@link DynaProperty} should be created.
     */
    public boolean isReturnNull() {
        return returnNull;
    }

    /**
     * Set whether this DynaClass should return a <code>null</code> from
     * the <code>getDynaProperty(name)</code> method if the property
     * doesn't exist.
     *
     * @param returnNull <code>true<code> if a <code>null</code> {@link DynaProperty}
     * should be returned if the property doesn't exist, otherwise
     * <code>false</code> if a new {@link DynaProperty} should be created.
     */
    public void setReturnNull(boolean returnNull) {
        this.returnNull = returnNull;
    }


    // ------------------- Protected Methods ----------------------------------

   /**
     * <p>Indicate whether a property actually exists.</p>
     *
     * <p><strong>N.B.</strong> Using <code>getDynaProperty(name) == null</code>
     * doesn't work in this implementation because that method might
     * return a DynaProperty if it doesn't exist (depending on the
     * <code>returnNull</code> indicator).</p>
     *
     * @param name Name of the dynamic property
     * @return <code>true</code> if the property exists,
     * otherwise <code>false</code>
     * @exception IllegalArgumentException if no property name is specified
     */
    protected boolean isDynaProperty(String name) {

        if (name == null) {
            throw new IllegalArgumentException("Property name is missing.");
        }

        return values.containsKey(name);

    }

}