python从Mjpg-streamer中取出一张jpg照片

#!/usr/bin/env python
# encoding=utf-8

import time		#导入定时
import urllib2	#导入url
import re		#导入正则
import commands	#导入调用shell命令模块

def mjpg_jpg():
commands.getstatusoutput('/etc/init.d/mjpg-streamer start')	#开启mjpg-streamer进程
a = commands.getstatusoutput('ps')
print a
time.sleep(1)	#延时

req = urllib2.urlopen("http://192.168.1.1:8080/?action=stream")
buf = req.read(71)		#取出包含jpg长度的信息头
a = "\d+"			#设置匹配规则取出jpg数据长度
m = re.findall(a,buf)	#正则取出
print "jpg0:",m		#打印出来看看
buf_1 = req.read(27)	#取出mjpeg包含运行时间数据，没用扔掉
if len(m) > 0:
jpg_s0 = int(m[0])	#jpg长度转int
jpg0 = req.read(jpg_s0)	        #取出jpg数据
l = req.read(3)			#垃圾扔掉

buf = req.read(71)
a = "\d+"
m = re.findall(a,buf)
print "jpg1:", m
buf_1 = req.read(27)
if len(m) > 0:
jpg_s1 = int(m[0])
jpg1 = req.read(jpg_s1)
l = req.read(3)

buf = req.read(71)
a = "\d+"
m = re.findall(a,buf)
print "jpg2:",m
buf_1 = req.read(27)
if len(m) > 0:
jpg_s2 = int(m[0])
jpg2 = req.read(jpg_s2)
l = req.read(3)

buf = req.read(71)
a = "\d+"
m = re.findall(a,buf)
print "jpg3:",m
buf_1 = req.read(27)
if len(m) > 0:
jpg_s3 = int(m[0])
jpg3 = req.read(jpg_s3)
l = req.read(3)

buf = req.read(71)
a = "\d+"
m = re.findall(a,buf)
print "jpg4:",m
buf_1 = req.read(27)
if len(m) > 0:
jpg_s4 = int(m[0])
jpg4 = req.read(jpg_s4)
l = req.read(3)

#下面部分比列表中哪帧数据最大就用哪张
jpg_list = [jpg_s0,jpg_s1,jpg_s2,jpg_s3,jpg_s4]
aa = 0
for i in jpg_list:
if i>aa:
aa = i
if len(jpg0)==aa:
jpg = jpg0
elif len(jpg1)==aa:
jpg = jpg1
elif len(jpg2)==aa:
jpg = jpg2
elif len(jpg3)==aa:
jpg = jpg3
elif len(jpg4)==aa:
jpg = jpg4
print aa
print jpg_s0,jpg_s1,jpg_s2,jpg_s3,jpg_s4
#上面###########
#下面这部分将jpg写入以时间命名的文件名
b = time.strftime('%Y-%m-%d %H:%M:%S',time.localtime(time.time()))
c = b+".jpg"
print c
fp = open(c,"w")
fp.write(jpg)
fp.close()

commands.getstatusoutput('/etc/init.d/mjpg-streamer stop')	#关闭mjpg-streamer进程
a = commands.getstatusoutput('ps')
print a
if __name__ == '__main__':
mjpg_jpg()
#	time.sleep(0.5)		#延时0.5秒，防止占用cpu资源