Android Studio - 如何从图库中获取图像然后保存

I have an app that contains a button. when you press the button, the application will send you to your mobile phone's image gallery. you then select the image and it will appear on an imageview above the button. This all goes without a problem but the only bad thing is that when I close and reopen the app. the image is gone. Does anybody know a way to do this?I have an app that contains a button. when you