m_validator = new QRegExpValidator(QRegExp("^(?![0-9]+$)[a-zA-Z0-9]{30}"));
m_pwdLine = new QLineEdit(m_main_widget);
m_pwdLine->setValidator(m_validator);
m_pwdLine->setPlaceholderText(tr("请输入密码!"));
m_pwdLine->setEchoMode(QLineEdit::Password);//输入的密码以圆点显示