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Tomcat example source code file (DomUtil.java)

This example Tomcat source code file (DomUtil.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - Tomcat tags/keywords

document, document, dom, entityresolver, inputsource, io, ioexception, namednodemap, namednodemap, node, node, nullresolver, parser, resolveentity, sax, saxexception, string, string, xml

The Tomcat DomUtil.java source code

/*
 * 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.tomcat.util;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.StringReader;

import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import javax.xml.transform.OutputKeys;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerException;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.StreamResult;

import org.w3c.dom.Document;
import org.w3c.dom.NamedNodeMap;
import org.w3c.dom.Node;
import org.xml.sax.EntityResolver;
import org.xml.sax.InputSource;
import org.xml.sax.SAXException;


/**
 *  Few simple utils to read DOM
 *
 * @author Costin Manolache
 */
public class DomUtil {
    private static org.apache.juli.logging.Log log=
        org.apache.juli.logging.LogFactory.getLog( DomUtil.class );

    // -------------------- DOM utils --------------------

    /** Get the trimed text content of a node or null if there is no text
     */
    public static String getContent(Node n ) {
        if( n==null ) return null;
        Node n1=DomUtil.getChild(n, Node.TEXT_NODE);

        if( n1==null ) return null;

        String s1=n1.getNodeValue();
        return s1.trim();
    }

    /** Get the first element child.
     * @param parent lookup direct childs
     * @param name name of the element. If null return the first element.
     */
    public static Node getChild( Node parent, String name ) {
        if( parent==null ) return null;
        Node first=parent.getFirstChild();
        if( first==null ) return null;

        for (Node node = first; node != null;
             node = node.getNextSibling()) {
            //System.out.println("getNode: " + name + " " + node.getNodeName());
            if( node.getNodeType()!=Node.ELEMENT_NODE)
                continue;
            if( name != null &&
                name.equals( node.getNodeName() ) ) {
                return node;
            }
            if( name == null ) {
                return node;
            }
        }
        return null;
    }

    public static String getAttribute(Node element, String attName ) {
        NamedNodeMap attrs=element.getAttributes();
        if( attrs==null ) return null;
        Node attN=attrs.getNamedItem(attName);
        if( attN==null ) return null;
        return attN.getNodeValue();
    }

    public static void setAttribute(Node node, String attName, String val) {
        NamedNodeMap attributes=node.getAttributes();
        Node attNode=node.getOwnerDocument().createAttribute(attName);
        attNode.setNodeValue( val );
        attributes.setNamedItem(attNode);
    }
    
    public static void removeAttribute( Node node, String attName ) {
        NamedNodeMap attributes=node.getAttributes();
        attributes.removeNamedItem(attName);                
    }
    
    
    /** Set or replace the text value 
     */ 
    public static void setText(Node node, String val) {
        Node chld=DomUtil.getChild(node, Node.TEXT_NODE);
        if( chld == null ) {
            Node textN=node.getOwnerDocument().createTextNode(val);
            node.appendChild(textN);
            return;
        }
        // change the value
        chld.setNodeValue(val);           
    }

    /** Find the first direct child with a given attribute.
     * @param parent
     * @param elemName name of the element, or null for any 
     * @param attName attribute we're looking for
     * @param attVal attribute value or null if we just want any
     */ 
    public static Node findChildWithAtt(Node parent, String elemName,
                                        String attName, String attVal) {
        
        Node child=DomUtil.getChild(parent, Node.ELEMENT_NODE);
        if( attVal== null ) {
            while( child!= null &&
                    ( elemName==null || elemName.equals( child.getNodeName())) && 
                    DomUtil.getAttribute(child, attName) != null ) {
                child=getNext(child, elemName, Node.ELEMENT_NODE );
            }
        } else {
            while( child!= null && 
                    ( elemName==null || elemName.equals( child.getNodeName())) && 
                    ! attVal.equals( DomUtil.getAttribute(child, attName)) ) {
                child=getNext(child, elemName, Node.ELEMENT_NODE );
            }
        }
        return child;        
    }    
    

    /** Get the first child's content ( ie it's included TEXT node ).
     */
    public static String getChildContent( Node parent, String name ) {
        Node first=parent.getFirstChild();
        if( first==null ) return null;
        for (Node node = first; node != null;
             node = node.getNextSibling()) {
            //System.out.println("getNode: " + name + " " + node.getNodeName());
            if( name.equals( node.getNodeName() ) ) {
                return getContent( node );
            }
        }
        return null;
    }

    /** Get the first direct child with a given type
     */
    public static Node getChild( Node parent, int type ) {
        Node n=parent.getFirstChild();
        while( n!=null && type != n.getNodeType() ) {
            n=n.getNextSibling();
        }
        if( n==null ) return null;
        return n;
    }

    /** Get the next sibling with the same name and type
     */
    public static Node getNext( Node current ) {
        String name=current.getNodeName();
        int type=current.getNodeType();
        return getNext( current, name, type);
    }

    /** Return the next sibling with a given name and type
     */ 
    public static Node getNext( Node current, String name, int type) {
        Node first=current.getNextSibling();
        if( first==null ) return null;

        for (Node node = first; node != null;
             node = node.getNextSibling()) {
            
            if( type >= 0 && node.getNodeType() != type ) continue;
            //System.out.println("getNode: " + name + " " + node.getNodeName());
            if( name==null )
                return node;
            if( name.equals( node.getNodeName() ) ) {
                return node;
            }
        }
        return null;
    }

    public static class NullResolver implements EntityResolver {
        public InputSource resolveEntity (String publicId,
                                                   String systemId)
            throws SAXException, IOException
        {
            if( log.isTraceEnabled())
                log.trace("ResolveEntity: " + publicId + " " + systemId);
            return new InputSource(new StringReader(""));
        }
    }

    public static void setAttributes( Object o, Node parent)
    {
        NamedNodeMap attrs=parent.getAttributes();
        if( attrs==null ) return;

        for (int i=0; i<attrs.getLength(); i++ ) {
            Node n=attrs.item(i);
            String name=n.getNodeName();
            String value=n.getNodeValue();

            if( log.isTraceEnabled() )
                log.trace("Attribute " + parent.getNodeName() + " " +
                            name + "=" + value);
            try {
                IntrospectionUtils.setProperty(o, name, value);
            } catch( Exception ex ) {
                ex.printStackTrace();
            }
        }
    }

    /** Read XML as DOM.
     */
    public static Document readXml(InputStream is)
        throws SAXException, IOException, ParserConfigurationException
    {
        DocumentBuilderFactory dbf =
            DocumentBuilderFactory.newInstance();

        dbf.setValidating(false);
        dbf.setIgnoringComments(false);
        dbf.setIgnoringElementContentWhitespace(true);
        //dbf.setCoalescing(true);
        //dbf.setExpandEntityReferences(true);

        DocumentBuilder db = null;
        db = dbf.newDocumentBuilder();
        db.setEntityResolver( new NullResolver() );

        // db.setErrorHandler( new MyErrorHandler());

        Document doc = db.parse(is);
        return doc;
    }

    public static void writeXml( Node n, OutputStream os )
            throws TransformerException
    {
        TransformerFactory tf=TransformerFactory.newInstance();
        //identity
        Transformer t=tf.newTransformer();
        t.setOutputProperty(OutputKeys.INDENT, "yes");
        t.transform(new DOMSource( n ), new StreamResult( os ));
    }
}

Other Tomcat examples (source code examples)

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