xmlelement.java

Nano的XML解析器

/* XMLElement.java                                                 NanoXML/Java
 *
 * $Revision: 1.5 $
 * $Date: 2002/02/06 18:50:12 $
 * $Name: RELEASE_2_2_1 $
 *
 * This file is part of NanoXML 2 for Java.
 * Copyright (C) 2000-2002 Marc De Scheemaecker, All Rights Reserved.
 *
 * This software is provided 'as-is', without any express or implied warranty.
 * In no event will the authors be held liable for any damages arising from the
 * use of this software.
 *
 * Permission is granted to anyone to use this software for any purpose,
 * including commercial applications, and to alter it and redistribute it
 * freely, subject to the following restrictions:
 *
 *  1. The origin of this software must not be misrepresented; you must not
 *     claim that you wrote the original software. If you use this software in
 *     a product, an acknowledgment in the product documentation would be
 *     appreciated but is not required.
 *
 *  2. Altered source versions must be plainly marked as such, and must not be
 *     misrepresented as being the original software.
 *
 *  3. This notice may not be removed or altered from any source distribution.
 */

package net.n3.nanoxml;


import java.io.Serializable;
import java.util.Enumeration;
import java.util.Hashtable;
import java.util.Properties;
import java.util.Vector;


/**
 * XMLElement is an XML element. The standard NanoXML builder generates a
 * tree of such elements.
 *
 * @see net.n3.nanoxml.StdXMLBuilder
 *
 * @author Marc De Scheemaecker
 * @version $Name: RELEASE_2_2_1 $, $Revision: 1.5 $
 */
public class XMLElement implements IXMLElement, Serializable {

    /**
     * Necessary for serialization.
     */
    static final long serialVersionUID = -2383376380548624920L;


    /**
     * No line number defined.
     */
    public static final int NO_LINE = -1;


    /**
     * The parent element.
     */
    private IXMLElement parent;


    /**
     * The attributes of the element.
     */
    private Vector attributes;


    /**
     * The child elements.
     */
    private Vector children;


    /**
     * The name of the element.
     */
    private String name;


    /**
     * The full name of the element.
     */
    private String fullName;


    /**
     * The namespace URI.
     */
    private String namespace;


    /**
     * The content of the element.
     */
    private String content;


    /**
     * The system ID of the source data where this element is located.
     */
    private String systemID;


    /**
     * The line in the source data where this element starts.
     */
    private int lineNr;


    /**
     * Creates an empty element to be used for #PCDATA content.
     */
    public XMLElement() {
        this(null, null, null, NO_LINE);
    }


    /**
     * Creates an empty element.
     *
     * @param fullName the name of the element.
     */
    public XMLElement(String fullName) {
        this(fullName, null, null, NO_LINE);
    }


    /**
     * Creates an empty element.
     *
     * @param fullName the name of the element.
     * @param systemID the system ID of the XML data where the element starts.
     * @param lineNr   the line in the XML data where the element starts.
     */
    public XMLElement(String fullName,
                      String systemID,
                      int    lineNr) {
        this(fullName, null, systemID, lineNr);
    }


    /**
     * Creates an empty element.
     *
     * @param fullName  the full name of the element
     * @param namespace the namespace URI.
     */
    public XMLElement(String fullName,
                      String namespace) {
        this(fullName, namespace, null, NO_LINE);
    }


    /**
     * Creates an empty element.
     *
     * @param fullName  the full name of the element
     * @param namespace the namespace URI.
     * @param systemID  the system ID of the XML data where the element starts.
     * @param lineNr    the line in the XML data where the element starts.
     */
    public XMLElement(String fullName,
                      String namespace,
                      String systemID,
                      int    lineNr) {
        this.attributes = new Vector();
        this.children = new Vector(8);
        this.fullName = fullName;
        if (namespace == null) {
            this.name = fullName;
        } else {
            int index = fullName.indexOf(':');
            if (index >= 0) {
                this.name = fullName.substring(index + 1);
            } else {
                this.name = fullName;
            }
        }
        this.namespace = namespace;
        this.content = null;
        this.lineNr = lineNr;
        this.systemID = systemID;
        this.parent = null;
    }


    /**
     * Creates an element to be used for #PCDATA content.
     */
    public IXMLElement createPCDataElement() {
        return new XMLElement();
    }


    /**
     * Creates an empty element.
     *
     * @param fullName the name of the element.
     */
    public IXMLElement createElement(String fullName) {
        return new XMLElement(fullName);
    }


    /**
     * Creates an empty element.
     *
     * @param fullName the name of the element.
     * @param systemID the system ID of the XML data where the element starts.
     * @param lineNr   the line in the XML data where the element starts.
     */
    public IXMLElement createElement(String fullName,
                                     String systemID,
                                     int    lineNr) {
        return new XMLElement(fullName, systemID, lineNr);
    }


    /**
     * Creates an empty element.
     *
     * @param fullName  the full name of the element
     * @param namespace the namespace URI.
     */
    public IXMLElement createElement(String fullName,
                                     String namespace) {
        return new XMLElement(fullName, namespace);
    }


    /**
     * Creates an empty element.
     *
     * @param fullName  the full name of the element
     * @param namespace the namespace URI.
     * @param systemID  the system ID of the XML data where the element starts.
     * @param lineNr    the line in the XML data where the element starts.
     */
    public IXMLElement createElement(String fullName,
                                     String namespace,
                                     String systemID,
                                     int    lineNr) {
        return new XMLElement(fullName, namespace, systemID, lineNr);
    }


    /**
     * Cleans up the object when it's destroyed.
     */
    protected void finalize() throws Throwable {
        this.attributes.clear();
        this.attributes = null;
        this.children = null;
        this.fullName = null;
        this.name = null;
        this.namespace = null;
        this.content = null;
        this.systemID = null;
        this.parent = null;
        super.finalize();
    }


    /**
     * Returns the parent element. This method returns null for the root
     * element.
     */
    public IXMLElement getParent() {
        return this.parent;
    }


    /**
     * Returns the full name (i.e. the name including an eventual namespace
     * prefix) of the element.
     *
     * @return the name, or null if the element only contains #PCDATA.
     */
    public String getFullName() {
        return this.fullName;
    }


    /**
     * Returns the name of the element.
     *
     * @return the name, or null if the element only contains #PCDATA.
     */
    public String getName() {
        return this.name;
    }


    /**
     * Returns the namespace of the element.
     *
     * @return the namespace, or null if no namespace is associated with the
     *         element.
     */
    public String getNamespace() {
        return this.namespace;
    }


    /**
     * Sets the full name. This method also sets the short name and clears the
     * namespace URI.
     *
     * @param name the non-null name.
     */
    public void setName(String name) {
        this.name = name;
        this.fullName = name;
        this.namespace = null;
    }


    /**
     * Sets the name.
     *
     * @param fullName  the non-null full name.
     * @param namespace the namespace URI, which may be null.
     */
    public void setName(String fullName,
                        String namespace) {
        int index = fullName.indexOf(':');
        if ((namespace == null) || (index < 0)) {
            this.name = fullName;
        } else {
            this.name = fullName.substring(index + 1);
        }
        this.fullName = fullName;
        this.namespace = namespace;
    }


    /**
     * Adds a child element.
     *
     * @param child the non-null child to add.
     */
    public void addChild(IXMLElement child) {
        if (child == null) {
            throw new IllegalArgumentException("child must not be null");
        }
        if ((child.getName() == null) && (! this.children.isEmpty())) {
            IXMLElement lastChild = (IXMLElement) this.children.lastElement();

            if (lastChild.getName() == null) {
                lastChild.setContent(lastChild.getContent()
                                     + child.getContent());
                return;
            }
        }
        ((XMLElement)child).parent = this;
        this.children.addElement(child);
    }


    /**
     * Inserts a child element.
     *
     * @param child the non-null child to add.
     * @param index where to put the child.
     */
    public void insertChild(IXMLElement child,
                            int         index) {
        if (child == null) {
            throw new IllegalArgumentException("child must not be null");
        }
        if ((child.getName() == null) && (! this.children.isEmpty())) {
            IXMLElement lastChild = (IXMLElement) this.children.lastElement();
            if (lastChild.getName() == null) {
                lastChild.setContent(lastChild.getContent()
                                     + child.getContent());
                return;
            }
        }
        ((XMLElement) child).parent = this;
        this.children.insertElementAt(child, index);
    }


    /**
     * Removes a child element.
     *
     * @param child the non-null child to remove.
     */
    public void removeChild(IXMLElement child) {
        if (child == null) {
            throw new IllegalArgumentException("child must not be null");
        }
        this.children.removeElement(child);
    }


    /**
     * Removes the child located at a certain index.
     *
     * @param index the index of the child, where the first child has index 0.
     */
    public void removeChildAtIndex(int index) {
        this.children.removeElementAt(index);
    }


    /**
     * Returns an enumeration of all child elements.
     *
     * @return the non-null enumeration
     */
    public Enumeration enumerateChildren() {
        return this.children.elements();
    }


    /**
     * Returns whether the element is a leaf element.
     *
     * @return true if the element has no children.
     */
    public boolean isLeaf() {
        return this.children.isEmpty();
    }


    /**
     * Returns whether the element has children.
     *
     * @return true if the element has children.
     */
    public boolean hasChildren() {
        return (! this.children.isEmpty());
    }


    /**
     * Returns the number of children.
     *
     * @return the count.
     */
    public int getChildrenCount() {
        return this.children.size();
    }


    /**
     * Returns a vector containing all the child elements.
     *
     * @return the vector.
     */
    public Vector getChildren() {
        return this.children;
    }


    /**
     * Returns the child at a specific index.
     *
     * @param index the index of the child
     *
     * @return the non-null child
     *
     * @throws java.lang.ArrayIndexOutOfBoundsException
     *		if the index is out of bounds.
     */
    public IXMLElement getChildAtIndex(int index)
    throws ArrayIndexOutOfBoundsException {
        return (IXMLElement) this.children.elementAt(index);
    }
    

    /**
     * Searches a child element.
     *
     * @param name the full name of the child to search for.
     *
     * @return the child element, or null if no such child was found.
     */
    public IXMLElement getFirstChildNamed(String name) {
        Enumeration enum = this.children.elements();
        while (enum.hasMoreElements()) {
            IXMLElement child = (IXMLElement) enum.nextElement();
            String childName = child.getFullName();
            if ((childName != null) && childName.equals(name)) {
                return child;
            }
        }
        return null;
    }


    /**
     * Searches a child element.
     *
     * @param name      the name of the child to search for.
     * @param namespace the namespace, which may be null.
     *
     * @return the child element, or null if no such child was found.
     */
    public IXMLElement getFirstChildNamed(String name,
                                          String namespace) {
        Enumeration enum = this.children.elements();
        while (enum.hasMoreElements()) {
            IXMLElement child = (IXMLElement) enum.nextElement();
            String str = child.getName();
            boolean found = (str != null) && (str.equals(name));
            str = child.getNamespace();
            if (str == null) {
                found &= (name == null);
            } else {
                found &= str.equals(namespace);
            }
            if (found) {
                return child;
            }