code: public final void seek(String key) {
          if (key == null || key.length() < 1) return;
          final String[] keys = key.split("\\.");
          nextGoodChar(); //读掉 { [
          for (String key1 : keys) {
              while (this.hasNext()) {
                  String field = this.readSmallString();
                  readBlank();
                  if (key1.equals(field)) break;
                  skipValue();
              }
          }
  
      }
docs: 找到指定的属性值 例如: {id : 1, data : { name : 'a', items : [1,2,3]}} seek('data.items') 直接跳转到 [1,2,3];
  
  @param key 指定的属性名