abstractnamespace.java

Java的面向对象数据库系统的源代码

/*
 * Copyright 2001 (C) MetaStuff, Ltd. All Rights Reserved.
 *
 * This software is open source.
 * See the bottom of this file for the licence.
 *
 * $Id: AbstractNamespace.java,v 1.1 2003/11/02 18:06:06 per_nyfelt Exp $
 */

package org.dom4j.tree;

import org.dom4j.Element;
import org.dom4j.Namespace;
import org.dom4j.Node;
import org.dom4j.Visitor;

/** <p><code>AbstractNamespace</code> is a Flyweight AbstractNamespace that can be shared amongst nodes.</p>
  *
  * @author <a href="mailto:[e-mail]">James Strachan</a>
  * @version $Revision: 1.1 $
  */
public class AbstractNamespace extends AbstractNode implements Namespace {

    /** Cache of AbstractNamespace instances */
    protected static final NamespaceCache cache = new NamespaceCache();

    /** XML AbstractNamespace */
    public static final AbstractNamespace XML_NAMESPACE
        = cache.get("xml", "http://www.w3.org/XML/1998/namespace");

    /** No AbstractNamespace present */
    public static final AbstractNamespace NO_NAMESPACE
        = cache.get("", "");


    /** The prefix mapped to this namespace */
    private String prefix;

    /** The URI for this namespace */
    private String uri;

    /** A cached version of the hashcode for efficiency */
    private int hashCode;


    /** A helper method to return the AbstractNamespace instance
      * for the given prefix and URI
      *
      * @return an interned AbstractNamespace object
      */
    public static AbstractNamespace get(String prefix, String uri) {
        return cache.get(prefix, uri);
    }

    /** A helper method to return the AbstractNamespace instance
      * for no prefix and the URI
      *
      * @return an interned AbstractNamespace object
      */
    public static Namespace get(String uri) {
        return cache.get(uri);
    }

    /** @param prefix is the prefix for this namespace
      * @param uri is the URI for this namespace
      */
    public AbstractNamespace(String prefix, String uri) {
        this.prefix = (prefix != null) ? prefix : "";
        this.uri = (uri != null) ? uri : "";;
    }


    public short getNodeType() {
        return NAMESPACE_NODE;
    }

    /** @return the hash code based on the qualified name and the URI of the
      * namespace.
      */
    public int hashCode() {
        if ( hashCode == 0 ) {
            hashCode = createHashCode();
        }
        return hashCode;
    }

    /** Factory method to create the hashcode allowing derived classes to change the behaviour */
    protected int createHashCode() {
        int hashCode = uri.hashCode() ^ prefix.hashCode();
        if ( hashCode == 0 ) {
            hashCode = 0xbabe;
        }
        return hashCode;
    }


    public boolean equals(Object object) {
        if ( this == object ) {
            return true;
        }
        else if ( object instanceof Namespace ) {
            Namespace that = (Namespace) object;

            // we cache hash codes so this should be quick
            if ( hashCode() == that.hashCode() ) {
                return uri.equals( that.getURI() )
                    && prefix.equals( that.getPrefix() );
            }
        }
        return false;
    }

    public String getText() {
        return uri;
    }

    public String getStringValue() {
        return uri;
    }

    /** @return the prefix for this <code>AbstractNamespace</code>.
      */
    public String getPrefix() {
        return prefix;
    }

    /** @return the URI for this <code>AbstractNamespace</code>.
      */
    public String getURI() {
        return uri;
    }


    public String getXPathNameStep() {
        if (prefix != null && !"".equals( prefix )) {
            return "namespace::" + prefix;
        }
        return "namespace::*[name()='']";
    }

    public String getPath(Element context) {
        StringBuffer path = new StringBuffer(10);
        Element parent = getParent();
        if (parent != null && parent != context) {
            path.append( parent.getPath( context ) );
            path.append( '/' );
        }
        path.append( getXPathNameStep() );
        return path.toString();
    }

    public String getUniquePath(Element context) {
        StringBuffer path = new StringBuffer(10);
        Element parent = getParent();
        if (parent != null && parent != context) {
            path.append( parent.getUniquePath( context ) );
            path.append( '/' );
        }
        path.append( getXPathNameStep() );
        return path.toString();
    }

    public String toString() {
        return super.toString() + " [AbstractNamespace: prefix " + getPrefix()
            + " mapped to URI \"" + getURI() + "\"]";
    }

    public String asXML() {
        StringBuffer asxml = new StringBuffer(10);
        String prefix = getPrefix();
        if ( prefix != null && prefix.length() > 0 ) {
            asxml.append("xmlns:");
            asxml.append(prefix);
            asxml.append("=\"");
        }
        else {
            asxml.append("xmlns=\"");
        }
        asxml.append(getURI());
        asxml.append("\"");
        return asxml.toString();
    }

    public void accept(Visitor visitor) {
        visitor.visit(this);
    }

    protected Node createXPathResult(Element parent) {
        return new org.dom4j.tree.DefaultNamespace( parent, getPrefix(), getURI() );
    }

}




/*
 * Redistribution and use of this software and associated documentation
 * ("Software"), with or without modification, are permitted provided
 * that the following conditions are met:
 *
 * 1. Redistributions of source code must retain copyright
 *    statements and notices.  Redistributions must also contain a
 *    copy of this document.
 *
 * 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 name "DOM4J" must not be used to endorse or promote
 *    products derived from this Software without prior written
 *    permission of MetaStuff, Ltd.  For written permission,
 *    please contact [e-mail].
 *
 * 4. Products derived from this Software may not be called "DOM4J"
 *    nor may "DOM4J" appear in their names without prior written
 *    permission of MetaStuff, Ltd. DOM4J is a registered
 *    trademark of MetaStuff, Ltd.
 *
 * 5. Due credit should be given to the DOM4J Project
 *    (http://dom4j.org/).
 *
 * THIS SOFTWARE IS PROVIDED BY METASTUFF, LTD. AND CONTRIBUTORS
 * ``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
 * METASTUFF, LTD. 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.
 *
 * Copyright 2001 (C) MetaStuff, Ltd. All Rights Reserved.
 *
 * $Id: AbstractNamespace.java,v 1.1 2003/11/02 18:06:06 per_nyfelt Exp $
 */