code: private ResponseParseItem getJSONSignSourceData(AlipayRequest<?> request, String body) {
  
          String rootNode = request.getApiMethodName().replace('.', '_')
                            + AlipayConstants.RESPONSE_SUFFIX;
          String errorRootNode = AlipayConstants.ERROR_RESPONSE;
  
          int indexOfRootNode = body.indexOf(rootNode);
          int indexOfErrorRoot = body.indexOf(errorRootNode);
  
          if (indexOfRootNode > 0) {
  
              return parseJSONSignSourceData(body, rootNode, indexOfRootNode);
  
          } else if (indexOfErrorRoot > 0) {
  
              return parseJSONSignSourceData(body, errorRootNode, indexOfErrorRoot);
          } else {
              return null;
          }
      }
docs: 获取JSON响应加签内容串
  
  @param request
  @param body
  @return