code: public String getRealPath(final String path) {
      	if (path == null) return null;
      	if (isContextPathSet && path.startsWith(contextPath)) return webappPath + path.substring(contextPath.length());
          return webappPath + path;
      }
docs: Returns a String containing the real path for a given virtual path. For example, the path "/index.html" returns
  the absolute file path on the server's filesystem would be served by a request for
  "http://host/contextPath/index.html", where contextPath is the context path of this ServletContext.
  
  <p>The real path returned will be in a form appropriate to the computer and operating system on which the servlet
  container is running, including the proper path separators. This method returns null if the servlet container
  cannot translate the virtual path to a real path for any reason (such as when the content is being made
  available from a .war archive).</p>
  
  <p>
  JavaDoc copied from: <a href="http://download.oracle.com/javaee/1.3/api/javax/servlet/ServletContext.html#getRealPath%28java.lang.String%29">
  http://download.oracle.com/javaee/1.3/api/javax/servlet/ServletContext.html#getRealPath%28java.lang.String%29</a>
  </p>
  
  @param path a String specifying a virtual path
  @return a String specifying the real path, or null if the translation cannot be performed