Pyqt5 -在文件对话框图形用户界面关闭后无法运行代码

from PyQt5.QtWidgets import QApplication, QFileDialog, QMainWindow

class MainWindow(QMainWindow):
    def __init__(self):
        super().__init__()

    def open_file_dialog(self):
        file_dialog = QFileDialog()
        file_dialog.fileSelected.connect(self.file_selected)
        file_dialog.exec_()

    def file_selected(self, file_path):
        # 执行文件选择后的操作
        print("Selected file:", file_path)

app = QApplication([])
window = MainWindow()
window.open_file_dialog()
app.exec_()

from PyQt5.QtWidgets import QApplication, QFileDialog, QMainWindow

app = QApplication([])

file_dialog = QFileDialog()
file_path = file_dialog.getOpenFileName(None, "Open File", "", "All Files (*)")[0]

# 执行文件选择后的操作
print("Selected file:", file_path)

app.exec_()