Python写自动化之启动进程并获取进程输出

来源：互联网发布：查淘宝数据有哪些插件编辑：程序博客网时间：2024/06/18 08:51

当我们需要执行外部命令或自己写一个自动化执行器时，需要使用到启动进程并获取输出的操作

首先，我们启动进程采用Python的subprocess模块，为了保证标准输出和标准错误输出能够正常运行，启动两个线程来检测输出结果部分

class Daemon(threading.Thread):    def __init__(self, workDir, logFunction=None, *args):        threading.Thread.__init__(self)        self.process = None        self.args = args        self.workDir = workDir        self.errList = []        self.stdOut = ""        self.stdErr = ""        self.isEnd = False        self.logFunction = logFunction    def _start_process(self):        if self.workDir == "":            self.workDir = None        allParas = []        for arg in self.args:            if arg:                allParas.extend(arg)        commandStr = " ".join(allParas)        try:            commandStr = commandStr.encode("gbk")        except:            pass        try:            self.runPath = self.runPath.encode("gbk")        except:            pass        lines = ["@echo off"]        lines.append(commandStr)        tempFilePath = util.get_temp_file("bat")        tempScriptFile = open(tempFilePath, "w")        tempScriptFile.write("\n".join(lines))        tempScriptFile.close()        self.process = subprocess.Popen("\"" + tempFilePath + "\"", stdin=subprocess.PIPE,                                        stdout=subprocess.PIPE, stderr=subprocess.PIPE, cwd=self.workDir, shell=True)        # 循环输出标准输出内容，避免阻塞        stdoutThread = ReadLogThread(self.process.stdout)        stdoutThread.start()        stderrThread = ReadLogThread(self.process.stderr)        stderrThread.start()        while self.process.poll() is None:            time.sleep(0.01)        self.isEnd = True        self.stdOut, self.stdErr = stdoutThread.get_log(), stderrThread.get_log()    def run(self):        try:            self._start_process()        except:            log.exception(traceback.format_exc())    def stop(self):        try:            if self.process.pid == 0:                return            os.system("TaskKill /PID %s /T /F" % self.process.pid)        except:            log.exception(traceback.format_exc())            pass

在看下读取输出的线程代码：

class ReadLogThread(threading.Thread):    def __init__(self, _pipe):        threading.Thread.__init__(self)        self._pipe = _pipe        self.logList = []    def run(self):        while True:            try:                line = self._pipe.readline()                if line == "":                    break                self.logList.append(line)            except:                break    def get_log(self):        return "".join(self.logList)

ok，进程启动函数就封装完成了，那么提供给外部调用的接口怎么来写呢？

我们除了启动进程外，一般还会给进程加一个超时时间，那么代码如下：

def start_process(workDir, timeout=5 * 60, logFunction=None, *args):    daemon = Daemon(workDir, logFunction, *args)    daemon.start()    start = 0    isTimeout = False    daemonStd = ""    daemonErr = ""    while not daemon.isEnd:        if start > timeout:            daemon.stop()            isTimeout = True            daemonErr = "\n".join(daemon.errList)            break        time.sleep(0.1)        start += 0.1    if daemon.stdOut != "":        daemonStd = daemon.stdOut    if daemon.stdErr != "":        daemonErr = daemon.stdErr    return util.get_unicode_str(daemonStd), util.get_unicode_str(daemonErr), isTimeout

这样，外部调用方式就是process.start_process(workDir, timeout, logFunction, args)，然后就可以获取到标准输出、错误输出及是否执行超时等相关信息了

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