您可以将密码存储在项目数据中。大概是这样的：

QString getPassword(QTableWidgetItem *itm)
{
    return itm->data(Qt::UserRole).toString();
}

void hidePassword(QTableWidgetItem *itm)
{
    QString password = getPassword(itm);
    password = password.fill('*', password.length());
    itm->setText(password);
    itm->setData(Qt::AccessibleTextRole, false);
}

void showPassword(QTableWidgetItem *itm)
{
    QString password = getPassword(itm);
    itm->setText(password);
    itm->setData(Qt::AccessibleTextRole, true);
}

void setPassword(QTableWidgetItem *itm, const QString &password)
{
    itm->setData(Qt::UserRole, password);
    if (itm->data(Qt::AccessibleTextRole) == true) {
        showPassword(itm);
    } else {
        hidePassword(itm);
    }
}

MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent)
    , ui(new Ui::MainWindow)
{
    ui->setupUi(this);

    QTableWidgetItem *itm = new QTableWidgetItem();
    itm->setFlags(Qt::NoItemFlags);
    ui->tableWidget->setItem(0, 0, itm);

    setPassword(itm, "test");

    connect(ui->tableWidget, &QTableWidget::itemClicked, this, [itm](QTableWidgetItem *clickedItm){
        if (clickedItm == itm) {
            if (itm->data(Qt::AccessibleTextRole) == true) {
                hidePassword(itm);
            } else {
                showPassword(itm);
            }
        }
    });
}

我还使用了Qt：：AccessibleTextRole来存储密码是否显示，它似乎是免费的