cmd非运行完再保存，结果显示&保存同时进行

#coding:utf-8
"""
fps信息获取到文件
"""
import sys
import subprocess

class Logger(object):
    def __init__(self, filename="Default.log"):
        self.terminal = sys.stdout
        self.log = open(filename, "a")

    def write(self, message):
        self.terminal.write(message)
        self.log.write(message)
        self.log.flush()#这个用来将屏幕输出一行，就保存到txt一行，而不是等cmd运行完再保存
    def flush(self):
        pass

def main():
    sys.stdout = Logger("fps_01.txt")

    cmd="adb logcat -s sdktest"
   # 执行cmd命令，并读取返回值，屏幕无输出，文件有记录
    p = subprocess.Popen(cmd, stdout=subprocess.PIPE, universal_newlines=True)
    result_line = p.stdout.readline()

    while result_line:
        print(result_line)
        result_line = p.stdout.readline()

if __name__ == ‘__main__‘:
    main()