import  java.io.*;
 import  javax.servlet.*;
 import  javax.servlet.http.*;
 import  javax.xml.parsers.*;
 import  javax.xml.transform.*;

 import  org.w3c.dom.*;


 public   class  SendXML
     extends  HttpServlet {
   public  SendXML() {
  }
  
   public   void  doPost(HttpServletRequest request, HttpServletResponse response)  throws 
      ServletException, IOException {
    createAnswer(request,response);
  }

   public   void  createAnswer(HttpServletRequest request, HttpServletResponse response)  throws 
      ServletException, IOException {
  //здесь можем разобрать request  и что там с ним пришло      //request.getInputStream()...
 
    Document xmlResult = getXML();
    ByteArrayOutputStream ser = getByteOutputStream(xmlResult);
    response.setContentLength(ser.size());
    DataOutputStream dos =  new  DataOutputStream(response.getOutputStream());
     byte [] buffer = ser.toByteArray();
    dos.write(buffer);
    dos.close();
  }
  
   public  Document getXML() {
    DocumentBuilderFactory docBuidFact = DocumentBuilderFactory.newInstance();
     try  {
      DocumentBuilder documentFactory = docBuidFact.newDocumentBuilder();
      Document outDoc = documentFactory.newDocument();
      Element root = outDoc.createElement("hello");
      outDoc.appendChild(root);
      Element oneMore = createElement(outDoc, "world", "и тебе привет");
      root.appendChild(oneMore);
       return  outDoc;
    }
     catch  (DOMException ex) {
      ex.printStackTrace();
       return   null ;
    }
     catch  (ParserConfigurationException ex) {
       return   null ;
    }
  }
  
   public  Element createElement(Document outDoc,String nameElement,String textElement)  throws  DOMException {
    Element oneMore;
    oneMore = outDoc.createElement(nameElement);
    Text text = outDoc.createTextNode(textElement);
    oneMore.appendChild( text);
     return  oneMore;
  }
  
  
   private  ByteArrayOutputStream getByteOutputStream(Document xmlResult)  throws 
      TransformerFactoryConfigurationError {
    ByteArrayOutputStream ser =  new  ByteArrayOutputStream();
     try  {
      org.apache.xml.serialize.OutputFormat format =
           new  org.apache.xml.serialize.OutputFormat(org.apache.xml.serialize.Method.XML, "Windows-1251", true );
      org.apache.xml.serialize.XMLSerializer serializer =
           new  org.apache.xml.serialize.XMLSerializer(ser,format);
      serializer.serialize(xmlResult);
    }
     catch  (Exception ex1) {
      ex1.printStackTrace();
    }
     return  ser;
  }