【PyQt5】实现输入延迟响应：3秒无输入后自动读取内容

思路：每次输入框内容改变，都重置 QTimer 倒计时为 3 秒；当持续 3 秒无输入后，QTimer 超时，获取当前输入框内容。

---

UI 代码（untitled.py）：

from PyQt5 import QtCore, QtGui, QtWidgets


class Ui_Form(object):
    def setupUi(self, Form):
        Form.setObjectName("Form")
        Form.resize(400, 300)
        self.horizontalLayout = QtWidgets.QHBoxLayout(Form)
        self.horizontalLayout.setObjectName("horizontalLayout")
        self.verticalLayout = QtWidgets.QVBoxLayout()
        self.verticalLayout.setObjectName("verticalLayout")
        self.plain_text_edit = QtWidgets.QPlainTextEdit(Form)
        self.plain_text_edit.setObjectName("plainTextEdit")
        self.verticalLayout.addWidget(self.plain_text_edit)
        self.label = QtWidgets.QLabel(Form)
        self.label.setText("")
        self.label.setAlignment(QtCore.Qt.AlignLeading|QtCore.Qt.AlignLeft|QtCore.Qt.AlignVCenter)
        self.label.setObjectName("label")
        self.verticalLayout.addWidget(self.label)
        self.verticalLayout.setStretch(0, 1)
        self.verticalLayout.setStretch(1, 1)
        self.horizontalLayout.addLayout(self.verticalLayout)

        self.retranslateUi(Form)
        QtCore.QMetaObject.connectSlotsByName(Form)

    def retranslateUi(self, Form):
        _translate = QtCore.QCoreApplication.translate
        Form.setWindowTitle(_translate("Form", "Form"))

逻辑代码：

import sys

from PyQt5.QtWidgets import *
from PyQt5.QtCore import *

from untitled import Ui_Form  # UI 代码：untitled.py


class MyWindow(QWidget, Ui_Form):
    def __init__(self):
        super(MyWindow, self).__init__()
        self.setupUi(self)

        self.plain_text_edit.textChanged.connect(self.reset_timer)  # 检测输入框文本改变

        self.timer = QTimer()
        self.timer.setSingleShot(True)  # 设置为单次触发，即定时器超时后只触发一次，避免多余触发
        self.timer.timeout.connect(self.get_text)  # 超时（3000ms）后获取当前输入框内容

    def reset_timer(self):
        print("重置 timer 倒计时为 3000ms")
        self.timer.start(3000)

    def get_text(self):
        print("读取 plain_text_edit 文本，并设置到 label 中")
        self.label.setText(self.plain_text_edit.toPlainText())


app = QApplication(sys.argv)
mw = MyWindow()
mw.show()
sys.exit(app.exec_())