1. 含义

PRODUCT_BOOT_JARS 最终被编译到system/framework，并被添加到BOOTCLASSPATH路径；

2.1 引用makefile

PRODUCT_BOOT_JARS += xxx.jar

2.2 DEXPREOPT_BOOT_JARS_MODULES

core/dex_preopt.mk

DEXPREOPT_BOOT_JARS := $(subst $(space),:,$(PRODUCT_BOOT_JARS))

DEXPREOPT_BOOT_JARS_MODULES := $(PRODUCT_BOOT_JARS)

2.3 核心

core/dex_preopt.mk

PRODUCT_BOOTCLASSPATH := $(subst $(space),:,$(foreach m,$(DEXPREOPT_BOOT_JARS_MODULES),/system/framework/$(m).jar))

core/dex_preopt.mk

$(foreach b,$(DEXPREOPT_BOOT_JARS_MODULES),$(eval $(call _dexpreopt-boot-jar-remove-classes.dex,$(b))))

2.4 _dexpreopt-boot-jar-remove-classes.dex

core/dex_preopt.mk

# Special rules for building stripped boot jars that override java_library.mk rules

# $(1): boot jar module name

define _dexpreopt-boot-jar-remove-classes.dex

_dbj_jar_no_dex := $(DEXPREOPT_BOOT_JAR_DIR_FULL_PATH)/$(1)_nodex.jar

_dbj_src_jar := $(call intermediates-dir-for,JAVA_LIBRARIES,$(1),,COMMON)/javalib.jar

$$(_dbj_jar_no_dex) : $$(_dbj_src_jar) | $(ACP) $(AAPT)

$$(call copy-file-to-target)

ifneq ($(DEX_PREOPT_DEFAULT),nostripping)

$$(call dexpreopt-remove-classes.dex,$$@)

endif

_dbj_jar_no_dex :=

_dbj_src_jar :=

endef

注释:

先编译$$(_dbj_src_jar), 然后对$$(_dbj_jar_no_dex) 做$(ACP) $(AAPT)

2.5 AAPT

core/config.mk

AAPT := $(HOST_OUT_EXECUTABLES)/aapt$(HOST_EXECUTABLE_SUFFIX)

core/combo/HOST_windows-x86.mk

HOST_EXECUTABLE_SUFFIX := .exe

2.6 ACP

core/config.mk

ACP := $(BUILD_OUT_EXECUTABLES)/acp$(BUILD_EXECUTABLE_SUFFIX)

2.7 DEXPREOPT_BOOT_JAR_DIR_FULL_PATH

DEXPREOPT_BOOT_JAR_DIR_FULL_PATH := $(DEXPREOPT_PRODUCT_DIR_FULL_PATH)/$(DEXPREOPT_BOOT_JAR_DIR)

DEXPREOPT_PRODUCT_DIR_FULL_PATH := $(PRODUCT_OUT)/dex_bootjars

DEXPREOPT_BOOT_JAR_DIR := system/framework

2.8 copy-file-to-target

core/definitions.mk

# The -t option to acp and the -p option to cp is

# required for OSX. OSX has a ridiculous restriction

# where it's an error for a .a file's modification time

# to disagree with an internal timestamp, and this

# macro is used to install .a files (among other things).

# Copy a single file from one place to another,

# preserving permissions and overwriting any existing

# file.

# We disable the "-t" option for acp cannot handle

# high resolution timestamp correctly on file systems like ext4.

# Therefore copy-file-to-target is the same as copy-file-to-new-target.

define copy-file-to-target

@mkdir -p $(dir $@)

$(hide) $(ACP) -fp $< $@

endef

2.9 PRODUCT_BOOTCLASSPATH

core/product.mk

_product_stash_var_list := $(_product_var_list) \

PRODUCT_BOOTCLASSPATH \

...

2.10stash-product-vars

core/product.mk

#

# Stash values of the variables in _product_stash_var_list.

# $(1): Renamed prefix

#

define stash-product-vars

$(foreach v,$(_product_stash_var_list), \

$(eval $(strip $(1))_$(call rot13,$(v)):=$$($$(v))) \

)

endef

system_server jar > framework.jar

总结：

BOOTCLASSPATH中中的jar编译为boot.art和boot.oat

实战

3.1 编写Jar包

结构

fox

├── Android.mk

└── java

└── com

└── android

└── host

└── fox

└── HelloFox.java

3.1.1 Android.mk

LOCAL_PATH := $(call my-dir)

include $(CLEAR_VARS)

LOCAL_MODULE := host-fox // 默认编译到system/framework

#LOCAL_MODULE_TAGS := optional

LOCAL_SRC_FILES := $(call all-java-files-under,java)

include $(BUILD_JAVA_LIBRARY)

3.1.2 HelloFox.java

package com.android.host.fox;

public class HelloFox {

public String say() {

return "Hello, host fox";

}

}

3.1.3 在系统makefile添加模块host-fox

# add jars

PRODUCT_PACKAGES += \

host-fox

// 添加到Android编译系统

PRODUCT_BOOT_JARS += host-fox // 添加到BOOTCLASSPATH路径

结果展示

host-fox.jpg