1，flutter组件尺寸是dp
https://www.jianshu.com/p/2ba69115f974
2、
https://blog.csdn.net/u011272795/article/details/82795477
3、约束
container默认最大，Row和Colum默认最大
flutter生命周期
https://blog.csdn.net/u011272795/article/details/82695920
flutter加载字符串
flutter学习笔记
https://www.jianshu.com/p/15223325850d
flutter tabbar+tabbarView
https://www.jianshu.com/p/68fa1c725415
tabView不会回收的方法
