element.java

一个用于搜索本地文件内容的小型搜索引擎

     *   parent or if the attribute namespace prefix collides with another
     *   namespace prefix on the element.
     */
    public Element setAttribute(final Attribute attribute) {
        attributes.add(attribute);
        return this;
    }

    /**
     * <p>
     * This removes the attribute with the given name and within no
     * namespace. If no such attribute exists, this method does nothing.
     * </p>
     *
     * @param name name of attribute to remove
     * @return whether the attribute was removed
     */
    public boolean removeAttribute(final String name) {
        return removeAttribute(name, Namespace.NO_NAMESPACE);
    }

    /**
     * <p>
     * This removes the attribute with the given name and within the
     * given Namespace.  If no such attribute exists, this method does
     * nothing.
     * </p>
     *
     * @param name name of attribute to remove
     * @param ns namespace URI of attribute to remove
     * @return whether the attribute was removed
     */
    public boolean removeAttribute(final String name, final Namespace ns) {
        return attributes.remove(name, ns);
    }

    /**
     * <p>
     * This removes the supplied Attribute should it exist.
     * </p>
     *
     * @param attribute Reference to the attribute to be removed.
     * @return whether the attribute was removed
     */
    public boolean removeAttribute(final Attribute attribute) {
        return attributes.remove(attribute);
    }

    /**
     * <p>
     *  This returns a <code>String</code> representation of the
     *    <code>Element</code>, suitable for debugging. If the XML
     *    representation of the <code>Element</code> is desired,
     *    {@link org.jdom.output.XMLOutputter#outputString(Element)}
     *    should be used.
     * </p>
     *
     * @return <code>String</code> - information about the
     *         <code>Element</code>
     */
    public String toString() {
        final StringBuffer stringForm = new StringBuffer(64)
            .append("[Element: <")
            .append(getQualifiedName());

        final String nsuri = getNamespaceURI();
        if (!"".equals(nsuri)) {
            stringForm
            .append(" [Namespace: ")
            .append(nsuri)
            .append("]");
        }
        stringForm.append("/>]");

        return stringForm.toString();
    }

    /**
     * <p>
     *  This returns a deep clone of this element.
     *  The new element is detached from its parent, and getParent()
     *  on the clone will return null.
     * </p>
     *
     * @return the clone of this element
     */
   public Object clone() {

       // Ken Rune Helland <[e-mail]> is our local clone() guru

       final Element element = (Element) super.clone();

       // name and namespace are references to immutable objects
       // so super.clone() handles them ok

       // Reference to parent is copied by super.clone()
       // (Object.clone()) so we have to remove it
       // Actually, super is a Content, which has already detached in the
       // clone().
       // element.parent = null;

       // Reference to content list and attribute lists are copyed by
       // super.clone() so we set it new lists if the original had lists
       element.content = new ContentList(element);
       element.attributes = new AttributeList(element);

       // Cloning attributes
       if (attributes != null) {
           for(int i = 0; i < attributes.size(); i++) {
               final Attribute attribute = (Attribute) attributes.get(i);
               element.attributes.add(attribute.clone());
           }
       }

       // Cloning additional namespaces
       if (additionalNamespaces != null) {
           element.additionalNamespaces = new ArrayList(additionalNamespaces);
       }

       // Cloning content
       if (content != null) {
           for(int i = 0; i < content.size(); i++) {
               final Content c = (Content) content.get(i);
               element.content.add(c.clone());
           }
       }

       return element;
   }


    // Support a custom Namespace serialization so no two namespace
    // object instances may exist for the same prefix/uri pair
    private void writeObject(final ObjectOutputStream out) throws IOException {

        out.defaultWriteObject();

        // We use writeObject() and not writeUTF() to minimize space
        // This allows for writing pointers to already written strings
        out.writeObject(namespace.getPrefix());
        out.writeObject(namespace.getURI());

        if (additionalNamespaces == null) {
            out.write(0);
        }
        else {
            final int size = additionalNamespaces.size();
            out.write(size);
            for (int i = 0; i < size; i++) {
                final Namespace additional = (Namespace) additionalNamespaces.get(i);
                out.writeObject(additional.getPrefix());
                out.writeObject(additional.getURI());
            }
        }
    }

    private void readObject(final ObjectInputStream in)
        throws IOException, ClassNotFoundException {

        in.defaultReadObject();

        namespace = Namespace.getNamespace(
            (String)in.readObject(), (String)in.readObject());

        final int size = in.read();

        if (size != 0) {
            additionalNamespaces = new ArrayList(size);
            for (int i = 0; i < size; i++) {
                final Namespace additional = Namespace.getNamespace(
                    (String)in.readObject(), (String)in.readObject());
                additionalNamespaces.add(additional);
            }
        }
    }

    /**
     * Returns an iterator that walks over all descendants in document order.
     *
     * @return an iterator to walk descendants
     */
    public Iterator getDescendants() {
        return new DescendantIterator(this);
    }

    /**
     * Returns an iterator that walks over all descendants in document order
     * applying the Filter to return only elements that match the filter rule.
     * With filters you can match only Elements, only Comments, Elements or
     * Comments, only Elements with a given name and/or prefix, and so on.
     *
     * @param filter filter to select which descendants to see
     * @return an iterator to walk descendants within a filter
     */
    public Iterator getDescendants(final Filter filter) {
        final Iterator iterator = new DescendantIterator(this);
        return new FilterIterator(iterator, filter);
    }



    /**
     * This returns a <code>List</code> of all the child elements
     * nested directly (one level deep) within this element, as
     * <code>Element</code> objects.  If this target element has no nested
     * elements, an empty List is returned.  The returned list is "live"
     * in document order and changes to it affect the element's actual
     * contents.
     *
     * <p>
     * Sequential traversal through the List is best done with a Iterator
     * since the underlying implement of List.size() may not be the most
     * efficient.
     * </p>
     *
     * <p>
     * No recursion is performed, so elements nested two levels deep
     * would have to be obtained with:
     * <pre>
     * <code>
     *   Iterator itr = (currentElement.getChildren()).iterator();
     *   while(itr.hasNext()) {
     *     Element oneLevelDeep = (Element)itr.next();
     *     List twoLevelsDeep = oneLevelDeep.getChildren();
     *     // Do something with these children
     *   }
     * </code>
     * </pre>
     * </p>
     *
     * @return list of child <code>Element</code> objects for this element
     */
    public List getChildren() {
        return content.getView(new ElementFilter());
    }

    /**
     * This returns a <code>List</code> of all the child elements
     * nested directly (one level deep) within this element with the given
     * local name and belonging to no namespace, returned as
     * <code>Element</code> objects.  If this target element has no nested
     * elements with the given name outside a namespace, an empty List
     * is returned.  The returned list is "live" in document order
     * and changes to it affect the element's actual contents.
     * <p>
     * Please see the notes for <code>{@link #getChildren}</code>
     * for a code example.
     * </p>
     *
     * @param name local name for the children to match
     * @return all matching child elements
     */
    public List getChildren(final String name) {
        return getChildren(name, Namespace.NO_NAMESPACE);
    }

    /**
     * This returns a <code>List</code> of all the child elements
     * nested directly (one level deep) within this element with the given
     * local name and belonging to the given Namespace, returned as
     * <code>Element</code> objects.  If this target element has no nested
     * elements with the given name in the given Namespace, an empty List
     * is returned.  The returned list is "live" in document order
     * and changes to it affect the element's actual contents.
     * <p>
     * Please see the notes for <code>{@link #getChildren}</code>
     * for a code example.
     * </p>
     *
     * @param name local name for the children to match
     * @param ns <code>Namespace</code> to search within
     * @return all matching child elements
     */
    public List getChildren(final String name, final Namespace ns) {
        return content.getView(new ElementFilter(name, ns));
    }

    /**
     * This returns the first child element within this element with the
     * given local name and belonging to the given namespace.
     * If no elements exist for the specified name and namespace, null is
     * returned.
     *
     * @param name local name of child element to match
     * @param ns <code>Namespace</code> to search within
     * @return the first matching child element, or null if not found
     */
    public Element getChild(final String name, final Namespace ns) {
        final List elements = content.getView(new ElementFilter(name, ns));
        final Iterator iter = elements.iterator();
        if (iter.hasNext()) {
            return (Element) iter.next();
        }
        return null;
    }

    /**
     * This returns the first child element within this element with the
     * given local name and belonging to no namespace.
     * If no elements exist for the specified name and namespace, null is
     * returned.
     *
     * @param name local name of child element to match
     * @return the first matching child element, or null if not found
     */
    public Element getChild(final String name) {
        return getChild(name, Namespace.NO_NAMESPACE);
    }

    /**
     * <p>
     * This removes the first child element (one level deep) with the
     * given local name and belonging to no namespace.
     * Returns true if a child was removed.
     * </p>
     *
     * @param name the name of child elements to remove
     * @return whether deletion occurred
     */
    public boolean removeChild(final String name) {
        return removeChild(name, Namespace.NO_NAMESPACE);
    }

    /**
     * <p>
     * This removes the first child element (one level deep) with the
     * given local name and belonging to the given namespace.
     * Returns true if a child was removed.
     * </p>
     *
     * @param name the name of child element to remove
     * @param ns <code>Namespace</code> to search within
     * @return whether deletion occurred
     */
    public boolean removeChild(final String name, final Namespace ns) {
        final Filter filter = new ElementFilter(name, ns);
        final List old = content.getView(filter);
        final Iterator iter = old.iterator();
        if (iter.hasNext()) {
            iter.next();
            iter.remove();
            return true;
        }

        return false;
    }

    /**
     * <p>
     * This removes all child elements (one level deep) with the
     * given local name and belonging to no namespace.
     * Returns true if any were removed.
     * </p>
     *
     * @param name the name of child elements to remove
     * @return whether deletion occurred
     */
    public boolean removeChildren(final String name) {
        return removeChildren(name, Namespace.NO_NAMESPACE);
    }

    /**
     * <p>
     * This removes all child elements (one level deep) with the
     * given local name and belonging to the given namespace.
     * Returns true if any were removed.
     * </p>
     *
     * @param name the name of child elements to remove
     * @param ns <code>Namespace</code> to search within
     * @return whether deletion occurred
     */
    public boolean removeChildren(final String name, final Namespace ns) {
        boolean deletedSome = false;

        final Filter filter = new ElementFilter(name, ns);
        final List old = content.getView(filter);
        final Iterator iter = old.iterator();
        while (iter.hasNext()) {
            iter.next();
            iter.remove();
            deletedSome = true;
        }

        return deletedSome;
    }

}