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:

def parseoptions(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))
except getopt.getopterror, err:
usage(docstring)
print “**”, str(err), “**”
sys.exit(2)
path_specified = false
for o, a in opts:
if o in (“-h”, “–help”):
usage(docstring)
sys.exit()
elif o in (“-v”, “–verbose”):
options.verbose = true
elif o in (“-p”, “–path”):
options.search_path = a
elif o in (“–signapk_path”,):
options.signapk_path = a
elif o in (“–extra_singapk_args”,):
options.extra_signapk_args = shlex.split(a)
elif o in (“–java_path”,):
options.java_path = a
else:
if extra_option_handler is none or not extra_option_handler(o, a):
assert false, “unknown option \”%s\”” % (o,)
os.environ[“path”] = (os.path.join(options.search_path, “bin”) + os.pathsep + os.environ[“path”])
return args

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:

def option_handler(o, a):
if o in (“-b”, “–board_config”):
pass # deprecated
elif o in (“-k”, “–package_key”):
options.package_key = a
elif o in (“-i”, “–incremental_from”):
options.incremental_source = a
elif o in (“-w”, “–wipe_user_data”):
options.wipe_user_data = true
elif o in (“-n”, “–no_prereq”):
options.omit_prereq = true
elif o in (“-e”, “–extra_script”):
options.extra_script = a
elif o in (“-a”, “–aslr_mode”):
if a in (“on”, “on”, “true”, “true”, “yes”, “yes”):
options.aslr_mode = true
else:
options.aslr_mode = false
elif o in (“–worker_threads”):
options.worker_threads = int(a)
else:
return false
return true

一般生成oat全量包的参数argv如下:

代码如下:

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:

代码如下:

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’]

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