2024年5月25日发(作者：)

Android平台Overlay机制

Android overlay 机制允许在不修改packages中apk的情况下，来自定义

framework和package中的资源文件，实现资源的定制。来达到显示不同的UI得目的（如

MIUI）。

以下几类能够通过该机制定义：

(1)，Configurations (string, bool, bool-array)

(2)，Localization (string, string-array)

(3)，UI Appearance (color, drawable, layout, style, theme, animation)

(4)，Raw resources (audio, video, xml)

For detailed introduction on Android application resources, please refer to:

/guide/topics/resources/

1 为产品添加Overlay目录

1.1 Product Overlays与Device Overlays

有两种不同的overaly目录定义，来影响最终的效果:

PRODUCT_PACKAGE_OVERLAYS: used by a particular product

DEVICE_PACKAGE_OVERLAYS: used several products that share a common

device model

如果包含同一资源，那么 PRODUCT_PACKAGE_OVERLAYS 将覆盖

DEVICE_PACKAGE_OVERLAYS 中的, 这两个定义如下:

build/core/ (Line: 93)

1 LOCAL_RESOURCE_DIR :=

2 $(wildcard $(foreach dir, $(PRODUCT_PACKAGE_OVERLAYS),

3 $(addprefix $(dir)/, $(LOCAL_RESOURCE_DIR))))

4 $(wildcard $(foreach dir, $(DEVICE_PACKAGE_OVERLAYS),

5 $(addprefix $(dir)/, $(LOCAL_RESOURCE_DIR))))

6 $(LOCAL_RESOURCE_DIR)