code: public static final String getRelativeWebPath(final String oldPath, final String newPath) {
  		if (StringUtils.isEmpty(oldPath) || StringUtils.isEmpty(newPath)) {
  			return "";
  		}
  
  		String resultPath = buildRelativePath(newPath, oldPath, '/');
  
  		if (newPath.endsWith("/") && !resultPath.endsWith("/")) {
  			return resultPath + "/";
  		}
  
  		return resultPath;
  	}
docs: This method can calculate the relative path between two pathes on a web
  site. <br/>
  
  <pre>
  PathUtils.getRelativeWebPath( null, null )                                          = ""
  PathUtils.getRelativeWebPath( null, "http://plexus.codehaus.org/" )                 = ""
  PathUtils.getRelativeWebPath( "http://plexus.codehaus.org/", null )                 = ""
  PathUtils.getRelativeWebPath( "http://plexus.codehaus.org/",
  "http://plexus.codehaus.org/plexus-utils/index.html" )        = "plexus-utils/index.html"
  PathUtils.getRelativeWebPath( "http://plexus.codehaus.org/plexus-utils/index.html",
  "http://plexus.codehaus.org/"                                 = "../../"
  </pre>
  
  @param oldPath
  @param newPath
  @return a relative web path from <code>oldPath</code>.