drawable-ldpi (dpi=120, density=0.75) icon_size 32*32
drawable-mdpi (360x640) (dpi=160, density=1) icon_size 48*48
drawable-hdpi (540x960) (dpi=240, density=1.5) icon_size 72*72
drawable-xhdpi (720x1280) (dpi=320, density=2) icon_size 96*96
drawable-xxhdpi (1080x1920) (dpi=480, density=3) icon_size 144*144
xxxhdpi 4K（3840×2160） (dpi=540,density=4) icon_size 192*192
屏幕密度dpi = 160屏幕上，1dp = 1px