如何从属于MainWindow类的QlineEdit中读取文本，并使用python和pyqt将其用于Qthread类？

from PyQt5.QtWidgets import QApplication, QMainWindow, QLineEdit, QPushButton, QVBoxLayout, QWidget, QLabel
from PyQt5.QtCore import QThread, pyqtSignal

class WorkerThread(QThread):
    result = pyqtSignal(str)

    def __init__(self, text):
        super().__init__()
        self.text = text

    def run(self):
        # 在这里执行耗时的任务，可以使用self.text获取QLineEdit中的文本
        # ...

        # 任务完成后，发送结果给主线程
        self.result.emit("任务完成")

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

        self.line_edit = QLineEdit()
        self.button = QPushButton("开始任务")
        self.label = QLabel()

        layout = QVBoxLayout()
        layout.addWidget(self.line_edit)
        layout.addWidget(self.button)
        layout.addWidget(self.label)

        widget = QWidget()
        widget.setLayout(layout)
        self.setCentralWidget(widget)

        self.button.clicked.connect(self.start_task)

    def start_task(self):
        text = self.line_edit.text()

        # 创建WorkerThread对象，并连接信号和槽函数
        worker_thread = WorkerThread(text)
        worker_thread.result.connect(self.handle_result)

        # 启动线程
        worker_thread.start()

    def handle_result(self, result):
        self.label.setText(result)

if __name__ == "__main__":
    app = QApplication([])
    window = MainWindow()
    window.show()
    app.exec_()