This is a Sample Java Mapping Program for SAP PI Tool. Tested and Works Fine!

JM_SampleJavaMapping_PI.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.InputStreamReader;
import java.io.OutputStream;


/***** 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_SampleJavaMapping_PI 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_SampleJavaMapping_PI() 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!"); }
			
			//Open the input Stream
			try 
			{
				docInput = 	new BufferedReader(new InputStreamReader(in));
			} 
			catch (Exception e) 
			{
				throw new StreamTransformationException("err1: Unable to parse input document - ".concat(e.getMessage()));
			}
			
			//Read the data - The Data is available in inputData
			try 
			{
				while ((inputLine = docInput.readLine()) != null) {
					sourcePayload.append(inputLine);
				}
			}catch (Exception e){
				throw new StreamTransformationException("err2: Error in reading the payload - ".concat(e.getMessage()));
			}
			
			//Write the Data
			try
			{
				out.write(new String(sourcePayload).getBytes("UTF-8"));
			}
			catch(Exception e) { 
				throw new StreamTransformationException("err3: Error in Writing the payload back - ".concat(e.getMessage()));			
			}
			
			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); }
		}
	}
	

	/**
	 * @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.txt");
			FileOutputStream fout = new FileOutputStream("outputfile.txt");

			JM_SampleJavaMapping_PI instance = new JM_SampleJavaMapping_PI();
			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!"); }

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