code: private void loadBinlogImage() {
          ResultSetPacket rs = null;
          try {
              rs = query("show variables like 'binlog_row_image'");
          } catch (IOException e) {
              throw new CanalParseException(e);
          }
  
          List<String> columnValues = rs.getFieldValues();
          if (columnValues == null || columnValues.size() != 2) {
              // 可能历时版本没有image特性
              binlogImage = BinlogImage.FULL;
          } else {
              binlogImage = BinlogImage.valuesOf(columnValues.get(1));
          }
  
          if (binlogFormat == null) {
              throw new IllegalStateException("unexpected binlog image query result:" + rs.getFieldValues());
          }
      }
docs: 获取一下binlog image格式