获取当前的url

public static String getRequestURL(HttpServletRequest request) {
  if (request == null) {
   return "";
  }
  StringBuffer sbUrl = new StringBuffer();
  sbUrl.append(request.getContextPath());
  sbUrl.append(request.getServletPath());
  String strQuery = request.getQueryString();
  if (strQuery != null && !strQuery.equals("")) {
   sbUrl.append("?" + strQuery);
  }
  return sbUrl.toString();
 }