问题描述

我制作了一个 GUI，点击 下载" 按钮后，程序将从 FTP 服务器下载文件.这样做时，我希望标签更新，例如:"Connecting..." ->正在下载..." ->已下载！"我试过用线程模块做，但它似乎不起作用:

I made a GUI in which after I click "Download" button the program will download files from FTP server. When doing that I want the label to update e.g: "Connecting..." -> "Downloading..." -> "Downloaded!" I tried doing it with threading module but it seems to not work:

def updater(self):
    self.updateStatusText.setText("Status: Connecting...")

    thread = threading.Thread(target=self.download)
    thread.start()

    while thread.isAlive():
        self.updateStatusText.setText("Status: Still Downloading...")


def download(self):
    ftp = FTP('testdomain.com')
    ftp.login(user='username', passwd='password')

    ftp.cwd('/main_directory/')

    filename = 'testfile.bin'

    with open(filename, 'wb') as localfile:
        ftp.retrbinary('RETR ' + filename, localfile.write, 1024)

    ftp.quit()
    localfile.close()

它只是下载文件，根本不改变文本标签.我必须在这里使用 QThread 吗?我也尝试使用 asyncio，但等待 self.updateStatusText.setText("Connecting...") 似乎返回 None 并且我得到 TypeError...

It just downloads the file and doesn't change the text label at all. Do I have to use QThread here? I also tried using asyncio but awaiting self.updateStatusText.setText("Connecting...") seems to return None and I get TypeError...

推荐答案

下面的代码应该这样做:

The following code should do:

class DownloadThread(QtCore.QThread):

    data_downloaded = QtCore.pyqtSignal(object)

    def run(self):
        self.data_downloaded.emit('Connecting...')

        ftp = FTP('example.com')
        ftp.login(user='user', passwd='password')

        ftp.cwd('/main_directory/')

        self.data_downloaded.emit('Downloading...')

        filename = 'testfile.bin'
        with open(filename, 'wb') as localfile:
            ftp.retrbinary('RETR ' + filename, localfile.write)

        ftp.quit()

        self.data_downloaded.emit('Done')

class MainWindow(QtGui.QWidget):
    def __init__(self):
        super(MainWindow, self).__init__()
        self.label = QtGui.QLabel
        self.button = QtGui.QPushButton("Start")
        self.button.clicked.connect(self.start_download)
        layout = QtGui.QVBoxLayout()
        layout.addWidget(self.button)
        layout.addWidget(self.label)
        self.setLayout(layout)

    def start_download(self):
        self.thread = DownloadThread()
        self.thread.data_downloaded.connect(self.on_data_ready)
        self.thread.start()

    def on_data_ready(self, data):
        self.label.setText(unicode(data))

基于:在多线程 PyQT 中更新 GUI 元素.

您的后续问题:从另一个运行 FTP 下载的线程更新 PyQt 进度

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