This sample Java Mapping Shows how to iterate the XML message field by field.

JM_IteratePayloadXML.java

/***** Standard Java Libraries ********/
import java.io.BufferedReader;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.io.OutputStream;

import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;

import org.w3c.dom.Document;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;


/***** PI Specific Libraries *********/
import com.sap.aii.mapping.api.AbstractTrace;
import com.sap.aii.mapping.api.AbstractTransformation;
import com.sap.aii.mapping.api.StreamTransformationException;
import com.sap.aii.mapping.api.TransformationInput;
import com.sap.aii.mapping.api.TransformationOutput;


public class JM_IteratePayloadXML extends AbstractTransformation {
	
 
	BufferedReader docInput;
	
	String inputLine = "";
	String messageID = "";

	TransformationInput transInput = null;
	TransformationOutput transOutput = null;
	
	StringBuffer sourcePayload = new StringBuffer();
	StringBuffer destPayload = new StringBuffer();
	
	
	public static AbstractTrace trace;
	
	public boolean traceon;
	
	
	public JM_IteratePayloadXML() throws Exception
	{
		docInput = null;	
	}	
		
	public void transform(TransformationInput arg0, TransformationOutput arg1) throws StreamTransformationException 
	{
		
		trace = (AbstractTrace) getTrace(); //Capture trace object and write trace for debugging purpose.
		messageID = arg0.getInputHeader().getMessageId(); //Message ID only available if run from PI.
		traceon = true; //make it false if wants to run the program locally. Make it true always before compiling the code and deployment.
		
		if ( traceon ){ trace.addInfo("Java Mapping Program Started!"); }else{ System.out.println("Java Mapping Program Started!"); }

		transInput = arg0;
		transOutput = arg1;
		
		this.execute((InputStream) arg0.getInputPayload().getInputStream(), (OutputStream) arg1.getOutputPayload().getOutputStream());
				
		if ( traceon ){ trace.addInfo("Java Mapping Program Completed!"); }else{ System.out.println("Java Mapping Program Completed!"); }
	}
	
	public void execute(InputStream in, OutputStream out) throws StreamTransformationException {

		try {

			if ( traceon ){ trace.addInfo("Inside the Execute Method!"); }else{ System.out.println("Inside the Execute Method!"); }

			DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
			factory.setNamespaceAware(false);
			
			DocumentBuilder dBuilder = factory.newDocumentBuilder();
			
			Document doc = dBuilder.parse(in);
			doc.getDocumentElement().normalize();	
	        	extractChild(doc);
	        
	        	destPayload = destPayload.replace(0, 2, ""); //To remove \r\n first line. if not required then uncomment. 
	        	out.write(new String(destPayload).getBytes("UTF-8"));
	        	out.flush(); //flush the stream
			
			if (traceon){ trace.addInfo("Outside the Execute Method!"); }else{ System.out.println("Outside the Execute Method!"); }
			
		} catch (Exception e) {
		
			if( traceon ){ trace.addWarning("[Execute Method]**Error. " + e); }else{ System.out.println("[Execute Method]**Error. " + e); }
		}
	}
	
	public void extractChild(Node nodes){
        if (nodes == null) {
            return;
        }
        
        int type = nodes.getNodeType();
        switch (type) {
        	case Node.DOCUMENT_NODE: {
        		extractChild(((Document)nodes).getDocumentElement());
	            break;
	        }        
        	case Node.ELEMENT_NODE: {
        		System.out.print( "\r\n" + nodes.getNodeName() );
        		destPayload.append( "\r\n" + nodes.getNodeName() );
                NodeList childNodes = nodes.getChildNodes();
                if( childNodes != null ){
                    for (int loopIndex = 0; loopIndex < childNodes.getLength(); loopIndex++ ) {
                    	extractChild(childNodes.item(loopIndex));
                     }
                }
                break;
        	}
            case Node.TEXT_NODE: {
            	String value = nodes.getNodeValue().trim();            	
            	if( value != null && value.length() > 0 ){
            		destPayload.append( "=" + value );
            		System.out.print( "=" + value );
            	}            	
            	break;
            }   	
        }
        
	}

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		// This method is executed only on the local running and no effect running from PI mapping program 
		try {
			FileInputStream fin = new FileInputStream("inputfile.xml");
			FileOutputStream fout = new FileOutputStream("outputfile.txt");

			JM_IteratePayloadXML instance = new JM_IteratePayloadXML();
			instance.traceon = false; //This will help to print the output instead of trace.			
			instance.execute(fin, fout);
		} catch (FileNotFoundException e) {

			e.printStackTrace();
		} catch (StreamTransformationException e) {

			e.printStackTrace();
		} catch (Exception e) {

			e.printStackTrace();
		}		

	}
}


/************************************************************************************************************
//BONUS CODE: TO BINARY READ AND WRITE - GOOD WHEN NOTHING TO MASSAGE WITH DATA - FASTEST AS WELL
			int buffer;
			if ( traceon ){ trace.addInfo("Inside the Execute Method!"); }else{ System.out.println("Inside the Execute Method!"); }
			
			//Read and Write back the file
			while ((buffer = in.read()) != -1)
			{
					out.write(buffer);
			}
		
			out.flush();
		
			if (traceon){ trace.addInfo("Outside the Execute Method!"); }else{ System.out.println("Outside the Execute Method!"); }

*************************************************************************************************************/