boundcompoundpropertymodel.java

Wicket一个开发Java Web应用程序框架。它使得开发web应用程序变得容易而轻松。 Wicket利用一个POJO data beans组件使得它可以与任何持久层技术相结合。

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.wicket.model;

import java.util.ArrayList;

import org.apache.wicket.Component;
import org.apache.wicket.IClusterable;


/**
 * A compound property model that supports type conversions and property expression bindings.
 * 
 * @author Jonathan Locke
 */
public class BoundCompoundPropertyModel extends CompoundPropertyModel
{
	/**
	 * Internal binding representation.
	 * 
	 * @author Jonathan Locke
	 */
	private class Binding implements IClusterable
	{
		private static final long serialVersionUID = 1L;

		private final Component component;
		private final String propertyExpression;

		private Binding(final Component component, final String propertyExpression)
		{
			this.component = component;
			this.propertyExpression = propertyExpression;
		}

		/**
		 * @see Object#toString()
		 */
		public String toString()
		{
			StringBuffer sb = new StringBuffer("Binding(");
			sb.append(":component=[").append(component).append("]");
			sb.append(":expression=[").append(propertyExpression).append("]");
			sb.append(")");
			return sb.toString();
		}
	}

	private static final long serialVersionUID = 1L;

	/**
	 * List of Bindings. Although a Map would be a more natural implementation here, a List is much
	 * more compact in terms of space. Although it may take longer to find a component binding in
	 * theory, in practice it's unlikely that any BoundCompoundPropertyModel will really have enough
	 * bindings to matter.
	 */
	private final ArrayList bindings = new ArrayList(1);

	/**
	 * Constructor
	 * 
	 * @param model
	 *            The model object, which may or may not implement IModel
	 */
	public BoundCompoundPropertyModel(final Object model)
	{
		super(model);
	}

	/**
	 * Adds a property binding, using the component's id as the property expression.
	 * 
	 * @param component
	 *            The component to bind
	 * @return The component, for convenience in adding components
	 */
	public Component bind(final Component component)
	{
		if (component == null)
		{
			throw new IllegalArgumentException("component must be not null");
		}

		bindings.add(new Binding(component, component.getId()));
		return component;
	}

	/**
	 * Adds a property binding.
	 * 
	 * @param component
	 *            The component to bind
	 * @param propertyExpression
	 *            A property expression pointing to the property in this model
	 * @return The component, for convenience in adding components
	 */
	public Component bind(final Component component, final String propertyExpression)
	{
		if (component == null)
		{
			throw new IllegalArgumentException("component must be not null");
		}
		if (propertyExpression == null)
		{
			throw new IllegalArgumentException("propertyExpression must be not null");
		}

		bindings.add(new Binding(component, propertyExpression));
		return component;
	}

	/**
	 * @see org.apache.wicket.model.CompoundPropertyModel#detach()
	 */
	public void detach()
	{
		super.detach();

		// Minimize the size of the bindings list
		bindings.trimToSize();
	}

	/**
	 * @see java.lang.Object#toString()
	 */
	public String toString()
	{
		StringBuffer sb = new StringBuffer(super.toString());
		sb.append(":bindings=[");
		for (int i = 0, size = this.bindings.size(); i < size; i++)
		{
			if (i > 0)
			{
				sb.append(",");
			}
			sb.append(bindings.get(i));
		}
		sb.append("]");
		return sb.toString();
	}

	/**
	 * @param component
	 *            Component to get binding for
	 * @return The binding information
	 */
	private Binding getBinding(final Component component)
	{
		for (int i = 0; i < bindings.size(); i++)
		{
			final Binding binding = (Binding)bindings.get(i);
			if (component == binding.component)
			{
				return binding;
			}
		}
		return null;
	}

	/**
	 * @see org.apache.wicket.model.CompoundPropertyModel#propertyExpression(org.apache.wicket.Component)
	 */
	protected String propertyExpression(final Component component)
	{
		final Binding binding = getBinding(component);
		if (binding != null)
		{
			return binding.propertyExpression;
		}
		else if (component != null)
		{
			return component.getId();
		}
		return null;
	}
}