code: protected void postOperation(AipRequest request) {
          if (isBceKey.get()) {
              // add aipSdk param
              request.addParam("aipSdk", "java");
  
              String bodyStr = request.getBodyStr();
  
              try {
                  int len = bodyStr.getBytes(request.getContentEncoding()).length;
                  request.addHeader(Headers.CONTENT_LENGTH, Integer.toString(len));
              } catch (UnsupportedEncodingException e) {
                  e.printStackTrace();
              }
  
              request.addHeader(Headers.CONTENT_MD5, SignUtil.md5(bodyStr, request.getContentEncoding()));
  
              String timestamp = Util.getCanonicalTime();
              request.addHeader(Headers.HOST, request.getUri().getHost());
              request.addHeader(Headers.BCE_DATE, timestamp);
              request.addHeader(Headers.AUTHORIZATION, CloudAuth.sign(request, this.aipKey, this.aipToken, timestamp));
          }
          else {
              request.addParam("aipSdk", "java");
              request.addParam("access_token", accessToken);
          }
      }
docs: /*
  为公有云用户填充http header，传入的request中body&param已经ready
  对于DEV用户，则将access_token放到url中