Sure - its easy enough. The example below sends an xml file as a String
to a servlet. It uses apache commons HttpClient - but you could also
use the JDK class URLConnectionReader. Also, the example uses basic
authentication in the servlet container  - its easy enough to skip that
part if you don't need it. The servlet also returns a seperate string
to the caller:

package com.infoseg.mr.hclient;

import java.io.*;
import java.util.*;

import org.apache.commons.httpclient.HttpClient;
import org.apache.commons.httpclient.methods.EntityEnclosingMethod;
import org.apache.commons.httpclient.methods.PostMethod;
import org.apache.commons.httpclient.UsernamePasswordCredentials;

import com.infoseg.mr.security.*;

public class PostXML
{
 /** Configuração arquivo */
 private static ResourceBundle rb;
 private static String realm;
 private static String domain;
 private static String url;
 private static String username;
 private static String password;

  /** Configuração arquivo name */
 private final static String WZC_BUNDLE_NAME =
"com.infoseg.mr.hclient.post";

 /**
 Class Construtor
 */
 private PostXML()
 {
   try
   {
     getConfig();
   }
   catch (Exception e)
   {
     e.printStackTrace();
   }
 }

 public static void main(String[] args) throws Exception
 {
   StringBuffer outfile = null;
   try
   {
     PostXML post = new PostXML();
     post.getConfig();
     HttpClient client = new HttpClient();
     client.getState().setCredentials(realm, domain, new
UsernamePasswordCredentials(username, password));

     InputStream fis = PostXML.class.getResourceAsStream("at.xml");
     //convert file to String
     InputStreamReader isr = new InputStreamReader(fis);
     Reader in = new BufferedReader(isr);
     int ch;
     StringBuffer buffer = new StringBuffer();
     while ((ch = in.read()) > -1)
     {
       buffer.append((char)ch);
     }
     in.close();

     PostMethod method = new PostMethod(url);
     method.addParameter("xml", buffer.toString());
     int returnCode = client.executeMethod(method);
     String reposta = method.getResponseBodyAsString();
     System.out.println("return code: " + returnCode);
     System.out.println("Response body: " + reposta);

     if (200 == returnCode)
     {
       // write response to file
       String path = "/usr/local/logs/hclient/";
       outfile = new StringBuffer();
       outfile.append(path);
       outfile.append("hclient");
       outfile.append("-");
       outfile.append(WSSTokenizer.getFormattedCurrentTimeAsString());
       outfile.append(".xml");
       OutputStream bos = new FileOutputStream(outfile.toString());
       bos.write(reposta.getBytes());
       bos.close();
     }
     else
     {
       System.out.println("\n\nCannot create XML response file, HTTP
server returned error code: " + returnCode);
     }
   }
   catch (FileNotFoundException e)
   {
     System.err.println("\n\nCannot create XML file: " + outfile);
     e.printStackTrace();
   }
   catch (Exception e)
   {
     e.printStackTrace();
   }
 }

 /**
 Load the configuration needed for a secure web service invokation.
 <p>
 @exception  Exception  thrown if the requested
 config is not found or has problems.
 */
 private void getConfig()
 {
   try
   {
     //ResourceBundle vai throw se no tem campos
     rb = ResourceBundle.getBundle(WZC_BUNDLE_NAME);

     realm = rb.getString("realm");
     domain = rb.getString("domain");
     url = rb.getString("url");
     username = rb.getString("username");
     password = rb.getString("password");

     System.out.println("realm: " + realm);
     System.out.println("domain: " + domain);
     System.out.println("url: " + url);
     System.out.println("username: " + username);
     System.out.println("password: " + password);
   }
   catch (Exception e)
   {
     System.err.println ("\nConfiguration load failed\n");
     e.printStackTrace();
   }
 }
}

Config file:

realm=atualiza
domain=localhost
url=http://localhost:8080/jaxb/servlet/com.infoseg.mr.atualiza.controller.XMLReciever
username=yyy
password=zzz

Servlet:

public class XMLReciever extends HttpServlet
{

 public void service(HttpServletRequest req, HttpServletResponse res)
    throws ServletException, IOException
 {
   res.setContentType("text/html");
   PrintWriter out = res.getWriter();
   ResponseBuilder reposta = null;
   try
   {
     // Read XML parameter from HTTP message
     String xml = req.getParameter("xml");
     Fwlog.debug(this, Fwlog.WI, "XML received: " + xml);

     if ((null == xml) || (xml.length() < 1))
     {
       throw new java.lang.IllegalStateException("ERR: Invalid XML
received - cannot be null or blank");
     }
     // more code ...
     return another_xml_as_string;
   }
   catch (Exception e)
   {
     // boom!
   }

HTH,
Robert
http://www.braziloutsource.com/