将两个Python脚本集成到一个脚本中？

Question

我有两个Python脚本需要彼此通信。第一个是用PySide2制作的GUI。GUI包含用于控制蓝牙音频设备的简单控件（播放、暂停、下一步、上一步等）。这些命令使用我找到的第二个python脚本进行操作。第二个脚本是一个循环，它等待输入这些命令，并在执行这些命令后作出响应。我对编程相当陌生，我猜这实际上是连接前端和后端，但这是我以前从未做过的事情

我已经编写了一个简化版的GUI，只显示我需要的控件。“后端”也在下面，但最初可以在这里找到：https://scribles.net/controlling-bluetooth-audio-on-raspberry-pi/

我之前问过一个类似的问题，@eyllanesc在这里给了我一个可靠而有效的答案：Execute command to a Python script from separate Python script?但是，使用QProcess方法，我无法确定如何将print输出从后端输入前端脚本。但是，错误消息打印正确。我尝试过在后端使用sys.stdout，使用process.read的变体和QbyteArray，但似乎没有任何进展

我遇到的另一个问题是，只有在启动脚本之前连接了蓝牙设备，脚本才会工作。如果在它运行时断开连接并尝试重新连接，它将不再接受命令。如果还有一种方法可以监控设备是否正在播放/暂停，以便播放/暂停按钮可以根据设备状态进行更新，这也会很有用，但在这个阶段并不重要

有很多方法可以做到这一点，但我觉得最终将两个脚本集成到一个脚本中会更好，不过我愿意接受任何可行的解决方案。如果有人有任何建议或可以让我开始，我将非常感激

前端：

import sys
from PySide2.QtWidgets import *

class MainWindow(QWidget):
    def __init__(self):
        QWidget.__init__(self)

        self.playbtn = QPushButton("Play")
        self.nextbtn = QPushButton("Next")
        self.prevbtn = QPushButton("Prev")

        layout = QVBoxLayout()
        layout.addWidget(self.playbtn)
        layout.addWidget(self.nextbtn)
        layout.addWidget(self.prevbtn)

        self.setLayout(layout)

        self.playbtn.released.connect(self.btnplay)
        self.nextbtn.released.connect(self.btnnext)
        self.prevbtn.released.connect(self.btnprev)

    def btnplay(self): #play button turns into pause button upon being pressed
        status = self.playbtn.text()
        if status == "Play":
            self.playbtn.setText("Pause")
            print("Play Pressed")
        elif status == "Pause":
            self.playbtn.setText("Play")
            print("Pause pressed")

    def btnnext(self):
        print("Next pressed")

    def btnprev(self):
        print("Prev pressed")


app = QApplication(sys.argv)

window = MainWindow()
window.show()
app.exec_()

后端：

import dbus, dbus.mainloop.glib, sys
from gi.repository import GLib


def on_property_changed(interface, changed, invalidated):
    if interface != 'org.bluez.MediaPlayer1':
        return
    for prop, value in changed.items():
        if prop == 'Status':
            print('Playback Status: {}'.format(value))
        elif prop == 'Track':
            print('Music Info:')
            for key in ('Title', 'Artist', 'Album'):
                print('   {}: {}'.format(key, value.get(key, '')))


def on_playback_control(fd, condition):
    str = fd.readline()
    if str.startswith('play'):
        player_iface.Play()
    elif str.startswith('pause'):
        player_iface.Pause()
    elif str.startswith('next'):
        player_iface.Next()
    elif str.startswith('prev'):
        player_iface.Previous()
    elif str.startswith('vol'):
        vol = int(str.split()[1])
        if vol not in range(0, 128):
            print('Possible Values: 0-127')
            return True
        transport_prop_iface.Set(
            'org.bluez.MediaTransport1',
            'Volume',
            dbus.UInt16(vol))
    return True


if __name__ == '__main__':
    dbus.mainloop.glib.DBusGMainLoop(set_as_default=True)
    bus = dbus.SystemBus()
    obj = bus.get_object('org.bluez', "/")
    mgr = dbus.Interface(obj, 'org.freedesktop.DBus.ObjectManager')
    player_iface = None
    transport_prop_iface = None
    for path, ifaces in mgr.GetManagedObjects().items():
        if 'org.bluez.MediaPlayer1' in ifaces:
            player_iface = dbus.Interface(
                bus.get_object('org.bluez', path),
                'org.bluez.MediaPlayer1')
        elif 'org.bluez.MediaTransport1' in ifaces:
            transport_prop_iface = dbus.Interface(
                bus.get_object('org.bluez', path),
                'org.freedesktop.DBus.Properties')
    if not player_iface:
        sys.exit('Error: Media Player not found.')
    if not transport_prop_iface:
        sys.exit('Error: DBus.Properties iface not found.')

    bus.add_signal_receiver(
        on_property_changed,
        bus_name='org.bluez',
        signal_name='PropertiesChanged',
        dbus_interface='org.freedesktop.DBus.Properties')
    GLib.io_add_watch(sys.stdin, GLib.IO_IN, on_playback_control)
    GLib.MainLoop().run()

更新日期：2020年10月31日： 我一直在玩上面链接的问题中建议的QProcess类。通过在按钮按下功能上使用它，并在命令执行后添加sys.exit，它消除了始终连接设备的需要，但我仍然找不到从后端脚本接收print输出的方法。这也感觉像是一种非常肮脏的工作方式。它还保留了播放/暂停状态未自动更新的问题。如果有人有任何建议，我将不胜感激

import sys
import os.path
from PySide2.QtCore import *
from PySide2.QtWidgets import *

CURRENT_DIR = os.path.dirname(os.path.realpath(__file__))

class MainWindow(QWidget):
    def __init__(self):
        QWidget.__init__(self)

        self.playbtn = QPushButton("Play")
        self.nextbtn = QPushButton("Next")
        self.prevbtn = QPushButton("Prev")

        layout = QVBoxLayout()
        layout.addWidget(self.playbtn)
        layout.addWidget(self.nextbtn)
        layout.addWidget(self.prevbtn)

        self.setLayout(layout)

        self.playbtn.released.connect(self.btnplay)
        self.nextbtn.released.connect(self.btnnext)
        self.prevbtn.released.connect(self.btnprev)

    def btnplay(self):
        self.process = QProcess()
        self.process.readyReadStandardError.connect(self.handle_readyReadStandardError)
        self.process.readyReadStandardOutput.connect(self.handle_readyReadStandardOutput)
        self.process.setProgram(sys.executable)
        script_path = os.path.join(CURRENT_DIR, "test2.py")
        self.process.setArguments([script_path])
        self.process.start()

        status = self.playbtn.text()
        if status == "Play":
            command = "play"
            self.playbtn.setText("Pause")
            print("play pressed")
        elif status == "Pause":
            command = "pause"
            self.playbtn.setText("Play")
            print("pause pressed")

        msg = "{}\n".format(command)
        self.process.write(msg.encode())

    def btnnext(self):
        self.process = QProcess()
        self.process.readyReadStandardError.connect(self.handle_readyReadStandardError)
        self.process.readyReadStandardOutput.connect(self.handle_readyReadStandardOutput)
        self.process.setProgram(sys.executable)
        script_path = os.path.join(CURRENT_DIR, "test2.py")
        self.process.setArguments([script_path])
        self.process.start()

        command = "next"
        msg = "{}\n".format(command)
        self.process.write(msg.encode())
        print("next pressed")

    def btnprev(self):
        self.process = QProcess()
        self.process.readyReadStandardError.connect(self.handle_readyReadStandardError)
        self.process.readyReadStandardOutput.connect(self.handle_readyReadStandardOutput)
        self.process.setProgram(sys.executable)
        script_path = os.path.join(CURRENT_DIR, "test2.py")
        self.process.setArguments([script_path])
        self.process.start()

        command = "prev"
        msg = "{}\n".format(command)
        self.process.write(msg.encode())
        print("prev pressed")

    def handle_readyReadStandardError(self):
        print(self.process.readAllStandardError().data().decode())

    def handle_readyReadStandardOutput(self):
        print(self.process.readAllStandardOutput().data().decode())


app = QApplication(sys.argv)

window = MainWindow()
window.show()
app.exec_()

Answer 1

我不熟悉您在后端使用的是什么，但应该是这么简单：

# in your frontend
import NAME_OF_BACKEND_PY_FILE_HERE as backend
def btnplay(self): #play button turns into pause button upon being pressed
        status = self.playbtn.text()
        if status == "Play":
            self.playbtn.setText("Pause")
            print("Play Pressed")
            backend.on_playback_control("play")
        elif status == "Pause":
            self.playbtn.setText("Play")
            print("Pause pressed")
            backend.on_playback_control("pause")

    def btnnext(self):
        print("Next pressed")
        backend.on_playback_control("next")

    def btnprev(self):
        print("Prev pressed")
        backend.on_playback_control("prev")

在后端，您还应该删除这一行：if __name__ == '__main__': 并取消它下面的所有代码。我不知道该如何正常调用该函数，或者第二个变量“condition”的作用是什么。但这就是我能想到的

Answer 2

IMHO OP有一个XY问题，这给应用程序增加了不必要的复杂性，因为dbus eventloop可以与Qt one共存，如我在下面的示例中所示：

import sys

import dbus
import dbus.mainloop.glib

from PyQt5 import QtCore, QtWidgets


class AudioManager(QtCore.QObject):
    statusChanged = QtCore.pyqtSignal(str)
    infoChanged = QtCore.pyqtSignal(dict)

    def __init__(self, parent=None):
        super().__init__(parent)
        self._player_iface = None
        self._transport_prop_iface = None

    def initialize(self):
        bus = dbus.SystemBus()
        obj = bus.get_object("org.bluez", "/")
        mgr = dbus.Interface(obj, "org.freedesktop.DBus.ObjectManager")
        player_iface = None
        transport_prop_iface = None
        for path, ifaces in mgr.GetManagedObjects().items():
            if "org.bluez.MediaPlayer1" in ifaces:
                player_iface = dbus.Interface(
                    bus.get_object("org.bluez", path), "org.bluez.MediaPlayer1"
                )
            elif "org.bluez.MediaTransport1" in ifaces:
                transport_prop_iface = dbus.Interface(
                    bus.get_object("org.bluez", path), "org.freedesktop.DBus.Properties"
                )
        if not player_iface:
            raise Exception("Error: Media Player not found.")
        if not transport_prop_iface:
            raise Exception("Error: DBus.Properties iface not found.")

        self._player_iface = player_iface
        self._transport_prop_iface = transport_prop_iface

        bus.add_signal_receiver(
            self.handle_property_changed,
            bus_name="org.bluez",
            signal_name="PropertiesChanged",
            dbus_interface="org.freedesktop.DBus.Properties",
        )

    def play(self):
        self._player_iface.Play()

    def pause(self):
        self._player_iface.Pause()

    def next(self):
        self._player_iface.Next()

    def previous(self):
        self._player_iface.Previous()

    def set_volume(self, Volume):
        if Volume not in range(0, 128):
            raise ValueError("Possible Values: 0-127")
        self._transport_prop_iface.Set(
            "org.bluez.MediaTransport1", "Volume", dbus.UInt16(vol)
        )

    def handle_property_changed(self, interface, changed, invalidated):
        if interface != "org.bluez.MediaPlayer1":
            return
        for prop, value in changed.items():
            if prop == "Status":
                self.statusChanged.emit(value)
            elif prop == "Track":
                info = dict()
                for key in ("Title", "Artist", "Album"):
                    info[key] = str(value.get(key, ""))
                self.infoChanged.emit(info)


class MainWindow(QtWidgets.QWidget):
    def __init__(self, parent=None):
        super().__init__(parent)

        self._manager = AudioManager()
        self._manager.infoChanged.connect(self.handle_info_changed)
        self._manager.initialize()

        self.playbtn = QtWidgets.QPushButton("Play")
        self.nextbtn = QtWidgets.QPushButton("Next")
        self.prevbtn = QtWidgets.QPushButton("Prev")

        layout = QtWidgets.QVBoxLayout(self)
        layout.addWidget(self.playbtn)
        layout.addWidget(self.nextbtn)
        layout.addWidget(self.prevbtn)

        self.playbtn.released.connect(self._manager.play)
        self.nextbtn.released.connect(self._manager.next)
        self.prevbtn.released.connect(self._manager.previous)

    def handle_info_changed(self, info):
        print(info)


if __name__ == "__main__":
    dbus.mainloop.glib.DBusGMainLoop(set_as_default=True)

    app = QtWidgets.QApplication(sys.argv)

    w = MainWindow()
    w.show()

    app.exec_()