QLineEdit *pCommonLineEdit = new QLineEdit(this);

pCommonLineEdit->setPlaceholderText(QStringLiteral("密码由字母、数字、下划线组成，长度8-16位"));
//QStringLieral是Qt5中新引入的一个用来从“字符串常量”创建QString对象的宏

pCommonLineEdit->setEchoMode(QLineEdit::Password);

class PasswordLineEdit : public QLineEdit

{

    Q_OBJECT

public:

    explicit PasswordLineEdit(QWidget *parent = 0);

    ~PasswordLineEdit();

protected:

    virtual void keyPressEvent(QKeyEvent *event);

    virtual void mouseMoveEvent(QMouseEvent *event);

    virtual void mouseDoubleClickEvent(QMouseEvent *event);

};

PasswordLineEdit::PasswordLineEdit(QWidget *parent)

    : QLineEdit(parent)

{

    //设置无右键菜单

    setContextMenuPolicy(Qt::NoContextMenu);

    //设置无输入时密码提示

    setPlaceholderText(QStringLiteral("请输入密码"));

    //设置密码隐藏

    setEchoMode(QLineEdit::Password);

    //设置最大长度16位

    setMaxLength(16);

}

PasswordLineEdit::~PasswordLineEdit()

{

}

//屏蔽输入框全选、复制、粘贴功能

void PasswordLineEdit::keyPressEvent(QKeyEvent *event)

{

    if(event->matches(QKeySequence::SelectAll)

            || event->matches(QKeySequence::Copy)

            || event->matches(QKeySequence::Paste))

    {

        return;

    }

    QLineEdit::keyPressEvent(event);

}

//鼠标位于密码框中时不可移动

void PasswordLineEdit::mouseMoveEvent(QMouseEvent *event)

{

    Q_UNUSED(event);

}

//鼠标位于密码框中时不可移动

void PasswordLineEdit::mouseDoubleClickEvent(QMouseEvent *event)

{

    Q_UNUSED(event);

}

QLineEdit *pFilterLineEdit = new QLineEdit(this);

pFilterLineEdit->installEventFilter(new EventFilter(this));

pFilterLineEdit->setEchoMode(QLineEdit::Password);

pFilterLineEdit->setPlaceholderText(QStringLiteral("密码由字母、数字、下划线组成，长度8-16位"));

pFilterLineEdit->setContextMenuPolicy(Qt::NoContextMenu);

pFilterLineEdit->setMaxLength(16);

class EventFilter : public QObject

{

public:

    explicit EventFilter(QObject *parent = 0);

    ~EventFilter();

protected:

    virtual bool eventFilter(QObject *obj, QEvent *event);

};

EventFilter::EventFilter(QObject *parent)

    : QObject(parent)

{

}

EventFilter::~EventFilter()

{

}

bool EventFilter::eventFilter(QObject *obj, QEvent *event)

{

    QLineEdit *pLineEdit = qobject_cast<QLineEdit *>(obj);

    if (pLineEdit != NULL)

    {

        switch (event->type())

        {

        case QEvent::MouseMove:

        case QEvent::MouseButtonDblClick:

            return true;

        case QEvent::KeyPress:

        {

            QKeyEvent *pKeyEvent = static_cast<QKeyEvent*>(event);

            if(pKeyEvent->matches(QKeySequence::SelectAll)

                    || pKeyEvent->matches(QKeySequence::Copy)

                    || pKeyEvent->matches(QKeySequence::Paste))

            {

                return true;

            }

        }

        }

    }

    return QObject::eventFilter(obj, event);

}