framework/src/net/sf/tapestry/ComponentAddress.java

/*
 *  ====================================================================
 *  The Apache Software License, Version 1.1
 *
 *  Copyright (c) 2002 The Apache Software Foundation.  All rights
 *  reserved.
 *
 *  Redistribution and use in source and binary forms, with or without
 *  modification, are permitted provided that the following conditions
 *  are met:
 *
 *  1. Redistributions of source code must retain the above copyright
 *  notice, this list of conditions and the following disclaimer.
 *
 *  2. Redistributions in binary form must reproduce the above copyright
 *  notice, this list of conditions and the following disclaimer in
 *  the documentation and/or other materials provided with the
 *  distribution.
 *
 *  3. The end-user documentation included with the redistribution,
 *  if any, must include the following acknowledgment:
 *  "This product includes software developed by the
 *  Apache Software Foundation (http://www.apache.org/)."
 *  Alternately, this acknowledgment may appear in the software itself,
 *  if and wherever such third-party acknowledgments normally appear.
 *
 *  4. The names "Apache" and "Apache Software Foundation" and
 *  "Apache Tapestry" must not be used to endorse or promote products
 *  derived from this software without prior written permission. For
 *  written permission, please contact apache@apache.org.
 *
 *  5. Products derived from this software may not be called "Apache",
 *  "Apache Tapestry", nor may "Apache" appear in their name, without
 *  prior written permission of the Apache Software Foundation.
 *
 *  THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 *  WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 *  OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 *  DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
 *  ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 *  SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 *  LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 *  USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 *  ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 *  OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 *  OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 *  SUCH DAMAGE.
 *  ====================================================================
 *
 *  This software consists of voluntary contributions made by many
 *  individuals on behalf of the Apache Software Foundation.  For more
 *  information on the Apache Software Foundation, please see
 *  <http://www.apache.org/>.
 */
package net.sf.tapestry;

import java.io.Serializable;

/**
 * The ComponentAddress class contains the path to a component, allowing it to  
 * locate an instance of that component in a different 
 * {@link net.sf.tapestry.IRequestCycle}.
 * 
 * <p>This class needs to be used mostly when working with components
 * accessed via the {@link net.sf.tapestry.IRender} interface. 
 * It allows those components to serialize and
 * pass as a service parameter information about what component they have to 
 * talk to if control returns back to them. 
 * 
 * <p>This situation often occurs when the component used via IRender contains
 * Direct or Action links.
 * 
 * @version $Id$
 * @author mindbridge
 * @since 2.2
 * 
 */
public class ComponentAddress implements Serializable
{
    private String _pageName;
    private String _idPath;

    /**
     * Creates a new ComponentAddress object that carries the identification 
     * information of the given component (the page name and the ID path).
     * @param component the component to get the address of
     */
    public ComponentAddress(IComponent component)
    {
        this(component.getPage().getName(), component.getIdPath());
    }

    /**
     * Creates a new ComponentAddress using the given Page Name and ID Path
     * @param pageName the name of the page that contains the component
     * @param idPath the ID Path of the component
     */
    public ComponentAddress(String pageName, String idPath)
    {
        _pageName = pageName;
        _idPath = idPath;
    }

    /**
     * Creates a new ComponentAddress using the given Page Name and ID Path
     * relative on the provided Namespace
     * @param namespace the namespace of the page that contains the component
     * @param pageName the name of the page that contains the component
     * @param idPath the ID Path of the component
     */
    public ComponentAddress(
        INamespace namespace,
        String pageName,
        String idPath)
    {
        this(namespace.constructQualifiedName(pageName), idPath);
    }

    /**
     * Finds a component with the current address using the given RequestCycle.
     * @param objCycle the RequestCycle to use to locate the component
     * @return IComponent a component that has been initialized for the given RequestCycle
     */
    public IComponent findComponent(IRequestCycle cycle)
    {
        IPage objPage = cycle.getPage(_pageName);
        return objPage.getNestedComponent(_idPath);
    }

    /**
     * Returns the idPath of the component.
     * @return String the ID path of the component
     */
    public String getIdPath()
    {
        return _idPath;
    }

    /**
     * Returns the Page Name of the component.
     * @return String the Page Name of the component
     */
    public String getPageName()
    {
        return _pageName;
    }

    /**
     * @see java.lang.Object#hashCode()
     */
    public int hashCode()
    {
        int hash = _pageName.hashCode() * 31;
        if (_idPath != null)
            hash += _idPath.hashCode();
        return hash;
    }

    /**
     * @see java.lang.Object#equals(Object)
     */
    public boolean equals(Object obj)
    {
        if (!(obj instanceof ComponentAddress))
            return false;

        if (obj == this)
            return true;

        ComponentAddress objAddress = (ComponentAddress) obj;
        if (!getPageName().equals(objAddress.getPageName()))
            return false;

        String idPath1 = getIdPath();
        String idPath2 = objAddress.getIdPath();
        return (idPath1 == idPath2)
            || (idPath1 != null && idPath1.equals(idPath2));
    }

}