3.编写Android.mk文件，放入工程目录下

      LOCAL_PATH:= $(call my-dir)
      include $(CLEAR_VARS)
      LOCAL_MODULE_TAGS := optional
      LOCAL_SRC_FILES := $(call all-java-files-under, src)
      LOCAL_PACKAGE_NAME := helloworld
      LOCAL_CERTIFICATE := platform
      include $(BUILD_PACKAGE)
      # Use the folloing include to make our test apk.
      include $(call all-makefiles-under,$(LOCAL_PATH))

4.编译

　　　拷贝工程至packages/apps/下

      　　~$ cp -rf helloworld   ~/android/packages/apps/helloworld

        进入目录  ~/...../helloworld$ mm

        编译成功：out/target/product/product_name/system/app/helloworld.apk

4、运行

　　  安装在机子上运行之。 adb install xxx/helloworld.apk