设置-关于手机-版本号

设置-关于手机-版本号

./vendor/mediatek/proprietary/packages/apps/MtkSettings/src/com/android/settings/deviceinfo/BuildNumberPreferenceController.java找到函数getSummary

@Override
public CharSequence getSummary() {
    // 读取的是Build.DISPLAY的值
    return mExt.customeBuildNumber(BidiFormatter.getInstance().unicodeWrap(Build.DISPLAY));
}

frameworks/base/core/java/android/os/Build.java

/** A build ID string meant for displaying to the user */
public static final String DISPLAY = getString("ro.build.display.id");

ro.build.display.id在build/tools/buildinfo.sh里面赋值的

# 实际使用的是BUILD_DISPLAY_ID
echo "ro.build.display.id=$BUILD_DISPLAY_ID"

BUILD_DISPLAY_ID在build/make/core/sysprop.mk里面定义赋值的

# BUILD_DISPLAY_ID is shown under Settings -> About Phone
# 判断是否user版本
ifeq ($(TARGET_BUILD_VARIANT),user)
  # User builds should show:
  # release build number or branch.buld_number non-release builds
 
  # Dev. branches should have DISPLAY_BUILD_NUMBER set
  # 这里的区别就是要不要显示DISPLAY_BUILD_NUMBER
  ifeq (true,$(DISPLAY_BUILD_NUMBER))
    BUILD_DISPLAY_ID := $(BUILD_ID).$(BUILD_NUMBER_FROM_FILE) $(BUILD_KEYS)
  else
    BUILD_DISPLAY_ID := $(BUILD_ID) $(BUILD_KEYS)
  endif
else
  # Non-user builds should show detailed build information
  # 不是user版本就显示BUILD_DESC的值
  BUILD_DISPLAY_ID := $(BUILD_DESC)
endif

先看User版本

先找BUILD_ID

build/core/build_id.mk

BUILD_ID=SP1A.210812.016

再找BUILD_KEYS

build/core/sysprop.mk

# 判断默认的系统开发证书
ifeq ($(DEFAULT_SYSTEM_DEV_CERTIFICATE),build/make/target/product/security/testkey)
BUILD_KEYS := test-keys
else
BUILD_KEYS := dev-keys
endif

BUILD_NUMBER_FROM_FILE的位置

build/core/config.mk

# 从$(SOONG_OUT_DIR)/build_number.txt中读取
# 其实就是从out/soong/build_number.txt中读取
BUILD_NUMBER_FROM_FILE := $$(cat $(SOONG_OUT_DIR)/build_number.txt)

非User版本

BUILD_DISPLAY_ID使用的是BUILD_DESC的值， 在build/make/core/sysprop.mk里面定义的BUILD_DESC

# BUILD_ID: detail info; has the same info as the build fingerprint
BUILD_DESC := $(TARGET_PRODUCT)-$(TARGET_BUILD_VARIANT) $(PLATFORM_VERSION) $(BUILD_ID) $(BUILD_NUMBER_FROM_FILE) $(BUILD_VERSION_TAGS)

由$(TARGET_PRODUCT)、$(TARGET_BUILD_VARIANT)、$(PLATFORM_VERSION)、$(BUILD_ID)、$(BUILD_NUMBER_FROM_FILE)、$(BUILD_VERSION_TAGS)这些值组成

TARGET_PRODUCT：lunch选择的项

TARGET_BUILD_VARIANT：eng、userdebug、user

PLATFORM_VERSION：Android版本

BUILD_ID：build/core/build_id.mk

BUILD_NUMBER_FROM_FILE：

BUILD_VERSION_TAGS：

后面两个后续再更新...