按钮放在QlineEdit内部，界面更紧凑，体现了按钮和文本框的强关联。

def addButton(self,lineEdit):
        btn = QtWidgets.QPushButton("")
        icon1 = QtGui.QIcon()
        icon1.addPixmap(QtGui.QPixmap(":/image/images/th.png"), QtGui.QIcon.Normal, QtGui.QIcon.Off)
        btn.setIcon(icon1)
        btn.setStyleSheet("""QPushButton {
                               border: 0px solid #32CD32;
                             }""")
        btn.setCursor(Qt.PointingHandCursor);
        widgetAction = QtWidgets.QWidgetAction(self);
        widgetAction.setDefaultWidget(btn);
        lineEdit.addAction(widgetAction,QtWidgets.QLineEdit.TrailingPosition);
        return btn

 实现的如下效果：