头文件：

#ifndef WIDGET_H
#define WIDGET_H

#include <QWidget>
#include <QTimer>
#include <QTime>
#include <QTextToSpeech>
#include <QMessageBox>
QT_BEGIN_NAMESPACE
namespace Ui { class Widget; }
QT_END_NAMESPACE

class Widget : public QWidget
{
    Q_OBJECT

public:
    Widget(QWidget *parent = nullptr);
    ~Widget();
    QTimer* time;//一秒输出一次系统时间
    QTextToSpeech *speecher;//读者
    int id;//启动后1秒判断一次时间是否与系统时间相同
    int id2;//相同后3秒一次读内容，读三次后关闭
    void timerEvent(QTimerEvent *e);
private:
    Ui::Widget *ui;
public slots:
    void time_slots();

private slots:
    void on_okbut_clicked();
    void on_pushButton_clicked();
};
#endif // WIDGET_H

函数： 

#include "widget.h"
#include "ui_widget.h"

Widget::Widget(QWidget *parent)
    : QWidget(parent)
    ,time(new QTimer(this))
    ,speecher(new QTextToSpeech(this))
    , ui(new Ui::Widget)
{
    ui->setupUi(this);
    time->start(1000);
    connect(time,&QTimer::timeout,this,&Widget::time_slots);
}

Widget::~Widget()
{
    delete ui;
}

void Widget::timerEvent(QTimerEvent *e)
{
    if(e->timerId()==id){
        QTime t=QTime::currentTime();
        QString s=t.toString("hh::mm::ss");
        if(s==ui->lineEdit->text()){
            id2=startTimer(5000);
            speecher->say(ui->label->text());
        }
    }else if(e->timerId()==id2){
        static int count=0;
        if(count++<3){
            speecher->say(ui->label->text());
        }else{
            killTimer(id2);
        }
    }
}

void Widget::time_slots()
{

    QTime t=QTime::currentTime();
    QString s=t.toString("hh::mm::ss");
    ui->timelab->setText("系统时间："+s);
    ui->timelab->setAlignment(Qt::AlignCenter);

}


void Widget::on_okbut_clicked()
{
    if(ui->okbut->text()=="启动"){
        if(ui->lineEdit->text().size()>7){
            ui->okbut->setText("取消");
            id=startTimer(1000);
        }else{
            QMessageBox::critical(this,"错误","时间输入错误",QMessageBox::Ok);
            ui->lineEdit->clear();
        }
    }else{
        QMessageBox::information(this,"闹钟","闹钟已经取消!",QMessageBox::Ok);
        ui->okbut->setText("启动");
        ui->lineEdit->clear();
        killTimer(id);
        killTimer(id2);
    }
}

void Widget::on_pushButton_clicked()
{
    this->close();
}

 现象：