pyqt5 限制应用窗口只能打开一次```python from PyQt5.QtNetwork import QLoc

from PyQt5.QtNetwork import QLocalServer, QLocalSocket
 
app = QtWidgets.QApplication(sys.argv)
server_name = "your_server_name"
socket = QLocalSocket()
    
socket.connectToServer(server_name)
if socket.waitForConnected(1000):
    app.quit()
else:
    local_server = QLocalServer()
    local_server.listen(server_name)
    app.setQuitOnLastWindowClosed(False)
    select = Select()
    sys.exit(app.exec_())