code: function preloadRoute(json, router, controllers) {
    // 支持 '/router get func' 这种配置
    if (isString(json)) {
      let arr = json.split(/\s+/);
      const obj = {};
      obj.path = arr[0];
      switch (arr.length) {
        case 2:
          obj.controller = arr[1];
          break;
        case 3:
          obj.method = arr[1];
          obj.controller = arr[2];
          break;
      }
      json = obj;
    }
    if (isUndefined(json.path)) {
      forEach(json, (val, key) => _preloadRoute(adaptForRouter(val, key), router, controllers));
    } else {
      _preloadRoute(json, router, controllers);
    }
  }
docs: 挂载路由 { key1: val1, key2: val2, key3: {  } }
  @param {Object|String} json 单条路由规则对应的配置
  @param {koa-router|express.Router} router 路由挂在对象
  @param {Object} controllers controller集合