Python中的getopt函数使用详解
函数原型:
getopt.getopt(args,shortopts,longopts=[])
参数解释:
- args:args为需要解析的参数列表。一般使用sys.argv[1:],这样可以过滤掉第一个参数(ps:第一个参数是脚本的名称,它不应该作为参数进行解析)
- shortopts:简写参数列表
- longopts:长参数列表
返回值:
- opts:分析出的(option,value)列表对。
- args:不属于格式信息的剩余命令行参数列表。
源码分析
在Android生成OTA的build系统中,common.py文件中的ParseOptions函数就是用来解析输入参数的,我们来通过该函数的实现来分析一下getopt的使用。
函数源码如下:
defParseOptions(argv,docstring,extra_opts="",extra_long_opts=(),extra_option_handler=None): try: opts,args=getopt.getopt( argv,"hvp:s:x"+extra_opts, ["help","verbose","path=","signapk_path=","extra_signapk_args=","java_path=","public_key_suffix=","private_key_suffix=","device_specific=","extra="]+list(extra_long_opts)) exceptgetopt.GetoptError,err: Usage(docstring) print"**",str(err),"**" sys.exit(2) path_specified=False foro,ainopts: ifoin("-h","--help"): Usage(docstring) sys.exit() elifoin("-v","--verbose"): OPTIONS.verbose=True elifoin("-p","--path"): OPTIONS.search_path=a elifoin("--signapk_path",): OPTIONS.signapk_path=a elifoin("--extra_singapk_args",): OPTIONS.extra_signapk_args=shlex.split(a) elifoin("--java_path",): OPTIONS.java_path=a else: ifextra_option_handlerisNoneornotextra_option_handler(o,a): assertFalse,"unknownoption\"%s\""%(o,) os.environ["PATH"]=(os.path.join(OPTIONS.search_path,"bin")+os.pathsep+os.environ["PATH"]) returnargs
其中,extra_option_handler可以理解为函数指针,它的功能也是解析opts的键值对。
extra_option_handler源码如下:
defoption_handler(o,a): ifoin("-b","--board_config"): pass#deprecated elifoin("-k","--package_key"): OPTIONS.package_key=a elifoin("-i","--incremental_from"): OPTIONS.incremental_source=a elifoin("-w","--wipe_user_data"): OPTIONS.wipe_user_data=True elifoin("-n","--no_prereq"): OPTIONS.omit_prereq=True elifoin("-e","--extra_script"): OPTIONS.extra_script=a elifoin("-a","--aslr_mode"): ifain("on","On","true","True","yes","Yes"): OPTIONS.aslr_mode=True else: OPTIONS.aslr_mode=False elifoin("--worker_threads"): OPTIONS.worker_threads=int(a) else: returnFalse returnTrue
一般生成OAT全量包的参数argv如下:
argv=['-v','-p','out/host/linux-xxx','-k','build/target/product/security/testkey','out/target/product/xxx/obj/PACKAGING/target_files_intermediates/xxx-target_files.zip','out/target/product/xxx/xxx_20150723.1340-ota.zip']
首先,对参数进行分析,其中短参数包括:
-v,-p,-k,
经过解析后,生成的结果如下所示:
opts=[('-v',''),('-p','out/host/linux-x86'),('-k','build/target/product/security/testkey')] args=['out/target/product/xxx/obj/PACKAGING/target_files_intermediates/xxx-target_files.zip','out/target/product/xxx/xxx_20150723.1340-ota.zip']