code: protected String legalStr(HttpServletRequest request){
          String echoStr = "";
          if(StrUtil.isBlank(getToken()) || StrUtil.isBlank(getAESKey()) || StrUtil.isBlank(getCropId())){
              return echoStr;
          }
          try {
              WXBizMsgCrypt pc = new WXBizMsgCrypt(getToken(), getAESKey(), getCropId());
              echoStr = pc.verifyUrl(request.getParameter("msg_signature"), request.getParameter("timestamp"), request.getParameter("nonce"), request.getParameter("echostr"));
          } catch (AesException e) {
              e.printStackTrace();
          }
          return echoStr;
      }
docs: 验证请求URL是否正确的方法
  
  @param request 请求
  @return 结果