React成长路之踩坑路 Warning: setState(...): Can only update a mounted or mounting component. This usually means you called setState() on an unmounted component. This is a no-op. Please check

　　Warning: setState(...): Can only update a mounted or mounting component. This usually means you called setState() on an unmounted component. This is a no-op. Please check the code for the xxx component.

　　意思是我们对一个未组装的组建进行了setState()的操作，这种情况会出现在callback中，我们的异步请求返回数据之前，组件可能就已经被卸载了，等数据回来再使用setState就会报出上面的警告，所以我们应该手动在componentWillUnmount时设置组件已卸载的标志，在数据处理setState()时先判断组件是否仍被挂载，否则不再执行setState

　　解决办法

　　

componentDidMount() {
    this._isMounted = true   //设置组件是否被装载标志位
    this.getList()
  }

componentWillUnmount() {
    this._isMounted = false
  }

getList() {
    const user = this.props.user
    const result = getOrderListData(user)
    result.then(res => {
      return res.json()
    }).then(json => {
      if(this._isMounted) {   //在setState()之前先判断组件是否被装载
        this.setState({
          lists: json
        })
      }
    }).catch(ex => {
      if(_DEV_) {
        console.log('请求订单列表时报错报错' + ex.message)
      }
    })
  }