QNetworkAccessManager下载文件

好的，您可以通过以下代码来使用QNetworkAccessManager下载文件：

import sys
from PyQt5.QtCore import QUrl
from PyQt5.QtGui import QIcon
from PyQt5.QtWidgets import QApplication, QWidget, QVBoxLayout, QLabel, QPushButton, QProgressBar
from PyQt5.QtNetwork import QNetworkAccessManager, QNetworkRequest, QNetworkReply

class Downloader(QWidget):
    def __init__(self):
        super().__init__()

        self.initUI()

    def initUI(self):
        self.setWindowTitle('File Downloader')
        self.setFixedSize(300, 100)

        self.url_label = QLabel('URL:')
        self.url_input = QLineEdit(self)
        self.progress_bar = QProgressBar(self)
        self.progress_bar.setVisible(False)
        self.download_button = QPushButton('Download', self)

        layout = QVBoxLayout(self)
        layout.addWidget(self.url_label)
        layout.addWidget(self.url_input)
        layout.addWidget(self.download_button)
        layout.addWidget(self.progress_bar)

        self.download_button.clicked.connect(self.start_download)

    def start_download(self):
        url = self.url_input.text()
        if url:
            self.progress_bar.setVisible(True)
            self.progress_bar.setValue(0)
            self.download_button.setEnabled(False)

            self.manager = QNetworkAccessManager()
            self.manager.finished.connect(self.download_finished)
            self.manager.downloadProgress.connect(self.download_progress)

            request = QNetworkRequest(QUrl(url))
            self.reply = self.manager.get(request)

    def download_finished(self, reply):
        if reply.error() == QNetworkReply.NoError:
            filename = reply.url().fileName()
            with open(filename, 'wb') as f:
                f.write(reply.readAll())
            self.progress_bar.setValue(100)
        else:
            print(reply.errorString())

        self.download_button.setEnabled(True)

    def download_progress(self, received, total):
        if total > 0:
            self.progress_bar.setValue(int(received / total * 100))

if __name__ == '__main__':
    app = QApplication(sys.argv)
    downloader = Downloader()
    downloader.show()
    sys.exit(app.exec_())

这段代码使用PyQt5库来实现了一个简单的GUI界面，用户可以在界面上输入要下载的文件的URL，然后点击“Download”按钮开始下载。下载进度会以进度条的形式显示。

在代码中，我们创建了一个QNetworkAccessManager对象来处理网络请求，并通过调用QNetworkAccessManager的download()方法来下载文件。我们还使用QNetworkReply对象来处理下载进度和结果。