XOM API for Processing XML with Java

[Wolfgang Hoschek <wolfgang.hoschek AT mac.com>]

Attachments don't seem to work on this mailing list. So here is the  
program attached inline...


package nux.xom.sandbox;

import java.io.File;
import java.io.FileOutputStream;
import java.io.OutputStream;

import nu.xom.Attribute;
import nu.xom.Builder;
import nu.xom.Comment;
import nu.xom.Document;
import nu.xom.Element;
import nu.xom.Node;
import nu.xom.NodeFactory;
import nu.xom.Nodes;
import nu.xom.ProcessingInstruction;
import nu.xom.Text;
import nux.xom.io.StreamingSerializer;
import nux.xom.io.StreamingSerializerFactory;
import nux.xom.pool.XOMUtil;

/**
 * Efficiently appends an element to the end of an XML file, in a  
streaming manner.
 *
 * @author whoschek.AT.lbl.DOT.gov
 */
public class AppendDemo {

        public static void main(String[] args) throws Exception {
                OutputStream out = new FileOutputStream("/tmp/result.xml");
		StreamingSerializer serializer = new StreamingSerializerFactory 
().createXMLSerializer(out, "UTF-8");
		NodeFactory streamingNodeFactory = XOMUtil.getRedirectingNodeFactory 
(serializer);
		NodeFactory appendingNodeFactory = new AppendingNodeFactory 
(streamingNodeFactory);
		new Builder(appendingNodeFactory).build(new File(args[0])); //  
stream through
                
                // check results:
		System.out.println(new Builder().build(new File("/tmp/ 
result.xml")).toXML());
        }
        
        
        private static final class AppendingNodeFactory extends NodeFactory {
                
                private final NodeFactory child;
                
                public AppendingNodeFactory(NodeFactory child) {
                        this.child = child;
                }
                
                // replace this with whatever tree you want to see appended...
                private Element createNodeToAppend() {
                Element synonym = new Element("synonymx");
                synonym.addAttribute(new Attribute("name", "foo"));
                return synonym;
                }
                
            public Nodes finishMakingElement(Element element) {
                if (element.getParent() instanceof Document) {                
  
                        print(createNodeToAppend());
                        child.makeText("\n\n");
                }
                return child.finishMakingElement(element);
            }

            private void print(Element elem) {
    		child.startMakingElement(elem.getQualifiedName(),  
elem.getNamespaceURI());
                for (int i=0; i < elem.getAttributeCount(); i++) {
                        Attribute attr = elem.getAttribute(i);
    			child.makeAttribute(attr.getQualifiedName(),  
attr.getNamespaceURI(), attr.getValue(), attr.getType());
                }
                for (int i=0; i < elem.getChildCount(); i++) {
                        Node node = elem.getChild(i);
                        if (node instanceof Element) {
                                print((Element)node); // recurse
                        } else if (node instanceof Text) {
                                child.makeText(node.getValue());
                        } else if (node instanceof Comment) {
                                child.makeComment(node.getValue());
                        } else if (node instanceof ProcessingInstruction) {
                                ProcessingInstruction pi = 
(ProcessingInstruction) node;
                                
child.makeProcessingInstruction(pi.getTarget(), pi.getValue());
                        }
                }
                child.finishMakingElement(elem);
            }
        
            // remaining methods simply delegate through to child...
            public Element makeRootElement(String name, String namespace) {
                return child.makeRootElement(name, namespace);
            }

            public Element startMakingElement(String name, String namespace) {
                return child.startMakingElement(name, namespace);
            }
        
            public Document startMakingDocument() {
                return child.startMakingDocument();
            }
        
            public void finishMakingDocument(Document document) {
                child.finishMakingDocument(document);
            }

	    public Nodes makeAttribute(String name, String URI, String  
value, Attribute.Type type) {
                return child.makeAttribute(name, URI, value, type);
            }

            public Nodes makeComment(String data) {
                return child.makeComment(data);         
            }

	    public Nodes makeDocType(String rootElementName, String  
publicID, String systemID) {
                return child.makeDocType(rootElementName, publicID, systemID);
            }

            public Nodes makeText(String data) {
                return child.makeText(data);
            }

	    public Nodes makeProcessingInstruction(String target, String  
data) {
                return child.makeProcessingInstruction(target, data);
            }

        }
}



On Mar 2, 2007, at 11:13 AM, Wolfgang Hoschek wrote:

> If efficiency is not a concern, the XPath approaches outlined by  
> Grzegorz will be easy. A perhaps more syntactically convenient  
> alternative is to use the XQueryUtil.update() method. Both have the  
> same effect.
>
> However, if efficiency in terms of time and space is important, and  
> alternative approach via a streaming NodeFactory is needed, finding  
> the insertion point as the input document streams by, and appending  
> new elements to an output xml stream. I've attached a small program  
> that does the append in such a streaming manner. You might want to  
> adapt it for your purposes.
>
> But if efficiency really matters this is still not good enough  
> because with file based XML, each separate append still has to scan  
> the entire file to find the end, so appending many elements  
> separately will be O(N^2). You'll end up having to consider better  
> alternatives such as a database or B-trees such as embedded JDBM.
>
> Wolfgang.
>
>
> On Mar 2, 2007, at 1:58 AM, Narjis Malik wrote:
>
> > Hello,
> >
> >
> > I am working on XML files using nux and xPath, I want to append xml
> > doucument at a particular location, how can I do it....
> >
> > I will demonstrate my question with the following example
> >
> > i have a xml document
> > _____________________________________________________________________ 
> > ______________
> >
> > <?xml version="1.0" encoding="UTF-8"?>
> >
> > <service name="GetFutureSybmolization">
> >
> > <synonym name="bvcvcvc">
> >
> > </synonym>
> >
> > </service>
> >
> > _____________________________________________________________________ 
> > ________________
> >
> > now what i need , i want to append this xml file with new element :
> >
> > as i scan this xml and when there is service element with name =
> > "GetFutureSybolization"
> >
> > then i want to add new element <synonym name="XYZDGD"></synonym>
> >
> > please help me how can i do it...
> >
> > as i tried to do it but it append at the end of file but i cant  
> > append in
> > some where else
> >
> >
> >
> > waiting for a reply
> > _______________________________________________
> > XOM-interest mailing list
> > XOM-interest AT lists.ibiblio.org
> > http://lists.ibiblio.org/mailman/listinfo/xom-interest
>
> _______________________________________________
> XOM-interest mailing list
> XOM-interest AT lists.ibiblio.org
> http://lists.ibiblio.org/mailman/listinfo/xom-interest