直接的问题是那
Ui_MainWindow是一个类，而不是该类的实例。您必须将“窗口”
self传递给
DownloadThread。但这毕竟不是正确的解决方案。您无法从其他线程访问PyQt小部件。相反，请使用与您已经使用的相同的技术来更新状态文本（
带有文本标签的FTP下载，其中显示了下载的当前状态 ）。
class Ui_MainWindow(object): def download_file(self): self.thread = DownloadThread() self.thread.data_downloaded.connect(self.on_data_ready) self.thread.data_progress.connect(self.on_progress_ready) self.progress_initialized = False self.thread.start() def on_progress_ready(self, data): # The first signal sets the maximum, the other signals increase a progress if self.progress_initialized: self.progressBar.setValue(self.progressBar.value() + int(data)) else: self.progressBar.setMaximum(int(data)) self.progress_initialized = Trueclass DownloadThread(QtCore.QThread): data_downloaded = QtCore.pyqtSignal(object) data_progress = QtCore.pyqtSignal(object) def run(self): self.data_downloaded.emit('Status: Connecting...') with FTP('example.com') as ftp: ftp.login(user='user', passwd='pass') ftp.cwd('/some_directory/') filename = '100MB.bin' totalsize = ftp.size(filename) print(totalsize) # The first signal sets the maximum self.data_progress.emit(str(totalsize)) self.data_downloaded.emit('Status: Downloading...') with open(filename, 'wb') as self.localfile: ftp.retrbinary('RETR ' + filename, self.file_write) self.data_downloaded.emit('Status: Updated!') def file_write(self, data): self.localfile.write(data) # The other signals increase a progress self.data_progress.emit(str(len(data)))您的代码的其他更改：
global localfile
是一个坏习惯。使用self.localfile
代替。- 不需要
localfile.close()
，无需with
担心。 - 同样
ftp.quit()
应替换为with
。 - 无需
DownloadThread
从继承Ui_MainWindow
。
