QDialog实现软件下载安装过程监视

在使用QDialog实现软件下载安装过程的监视时，你可以结合Qt的网络请求库如QNetworkAccessManager，以及进度条控件QProgressBar。下面是一个简化的示例，展示如何在一个对话框中显示下载进度：

from PyQt5.QtCore import QTimer, pyqtSignal, Qt
from PyQt5.QtWidgets import QApplication, QDialog, QLabel, QProgressBar, QVBoxLayout, QPushButton
from PyQt5.QtNetwork import QNetworkReply, QNetworkRequest

class DownloadProgress(QDialog):
    downloadProgress = pyqtSignal(int)  # 自定义信号用于发送下载进度

    def __init__(self, url):
        super().__init__()
        self.url = url
        self.setWindowTitle('Download Monitor')
        self.resize(300, 150)

        self.download_label = QLabel('Downloading...', self)
        self.progress_bar = QProgressBar(self)

        layout = QVBoxLayout()
        layout.addWidget(self.download_label)
        layout.addWidget(self.progress_bar)
        self.setLayout(layout)

        self.download_button = QPushButton('Start Download', self)
        self.download_button.clicked.connect(self.start_download)
        layout.addWidget(self.download_button)

    def start_download(self):
        reply = QNetworkAccessManager().get(QNetworkRequest(self.url))
        reply.finished.connect(self.on_reply_finished)
        self.download_button.setEnabled(False)
        self.downloadProgress.connect(self.update_progress)

    def on_reply_finished(self, reply: QNetworkReply):
        if reply.error() != QNetworkReply.NoError:
            print(f"Error downloading: {reply.errorString()}")
        else:
            content_length = reply.headers().value("Content-Length")
            self.total_bytes = int(content_length) if content_length else 0
            self.download_thread = threading.Thread(target=self.download_in_background)
            self.download_thread.start()

    def update_progress(self, progress):
        self.download_label.setText(f'Downloaded {progress}%')
        self.progress_bar.setValue(progress)

    def download_in_background(self):
        data = reply.readAll()
        while True:
            chunk_size = 1024
            bytes_received = reply.bytesAvailable()
            if bytes_received < chunk_size:
                break
            downloaded_data = reply.read(chunk_size)
            self.downloadProgress.emit(len(downloaded_data))
            QApplication.processEvents()  # 更新UI线程

        # 完成下载后关闭连接
        reply.deleteLater()
        self.download_button.setEnabled(True)

if __name__ == '__main__':
    import sys
    from PyQt5.QtGui import QGuiApplication as QApplication
    app = QApplication(sys.argv)
    dialog = DownloadProgress('http://example.com/file_to_download.zip')
    dialog.show()
    sys.exit(app.exec_())

这个示例中，当用户点击“开始下载”按钮时，会发起一个HTTP GET请求并启动一个后台线程处理下载过程。下载过程中，每接收一定量的数据，就更新信号`downloadProgress`，然后主线程收到信号后更新进度条。