动画的
https://blog.csdn.net/MakerCloud/article/details/82082124 animator
https://www.jianshu.com/p/48d79eaf3470
综合的：
https://hndeveloper.github.io/2017/github-android-ui.html#TabBar
好的开源项目：
https://www.oschina.net/translate/25-new-android-libraries-and-projects-2018?lang=chs&p=2
代码下载不下来的时候
jcenter() { url "https://maven.aliyun.com/repository/jcenter" }
maven {
url 'https://dl.google.com/dl/android/maven2/'
}
git从新编辑ignore
git rm -r --cached .
git add .
git commit -m 'update .gitignore'
