QT開發（六十六）——登錄對話框的驗證機制

一、驗證碼機制

為了避免被惡意程序***，程序通常要使用安全機制。驗證碼機制是提供產生隨機驗證碼，由用戶識別填寫來判斷用戶有效性的安全機制。

驗證碼必須動態隨機產生，驗證碼的顯示必須避開使用標準組件（如標簽、文本框等），同時要增加足夠的障礙難度增加程序的識別難度。

基本的解決方案如下：

A、隨機產生目標驗證碼

B、將驗證碼直接繪制于登錄對話框

C、驗證碼中的字符顏色隨機變化

D、在驗證碼區域隨機繪制噪點

二、登錄對話框驗證碼機制實現

1、隨機數產生

計算機只能產生偽隨機數。

QString?getRandom() {QString?ret?=?"";for(int?i=0;?i<4;?i++){int?c?=?(qrand()?%?2)???'a'?:?'A';ret?+=?static_cast<QChar>(c?+?qrand()?%?26);}return?ret; }

2、驗證碼繪制

每次繪制單個驗證碼，使用隨機顏色的畫筆

for(int?i?=?0;?i?<?4;?i++){painter.setPen(m_colors[i]);painter.drawText(245?+?25*i,?150,?25,?30,?Qt::AlignCenter,?QString(m_verification[i]));}

3、噪點繪制

在驗證碼繪制矩形區域內隨機位置繪制噪點

for(int?i=0;?i<150;?i++){painter.setPen(m_colors[i%4]);painter.drawPoint(245?+?qrand()?%?99,?150?+?qrand()?%?29);}

4、代碼實例

????LoginDialog.h文件：

#ifndef?LOGINDIALOG_H #define?LOGINDIALOG_H#include?<QDialog> #include?<QLineEdit> #include?<QPushButton> #include?<QLabel> #include?<QTimer>class?LoginDialog:?public?QDialog {Q_OBJECT private:QLabel?UserLabel;QLabel?PwdLabel;QLabel?Verification;QLineEdit?VerificationEdit;QLineEdit?UserEdit;QLineEdit?PwdEdit;QPushButton?B_Login;QPushButton?B_Cancel;QString?m_user;QString?m_pwd;Qt::GlobalColor*?m_colors;QString?m_verification;QTimer?m_timer; private:Qt::GlobalColor*?getColors();QString?getVerificationCode();void?paintEvent(QPaintEvent?*event);void?mouseDoubleClickEvent(QMouseEvent?*event);private?slots:void?Login();void?Cancel();void?onTimeOut();public:LoginDialog(QWidget?*parent);QString?getUser();QString?getPwd();~LoginDialog(); };#endif?//?LOGINDIALOG_H

????LoginDialog.cpp文件：

#include?"LoginDialog.h" #include?<QDebug> #include?<QMessageBox> #include?<QPainter> #include?<QMouseEvent> #include?<QTime>LoginDialog::LoginDialog(QWidget?*parent):QDialog(parent,?Qt::WindowCloseButtonHint),?UserLabel(this),?PwdLabel(this),Verification(this),VerificationEdit(this),?UserEdit(this),?PwdEdit(this),?B_Login(this),B_Cancel(this) {UserLabel.setText("User?ID:");UserLabel.move(50,?50);UserLabel.resize(60,?30);UserEdit.move(110,?50);UserEdit.resize(200,?30);PwdLabel.setText("Password:");PwdLabel.move(50,?100);PwdLabel.resize(60,30);PwdEdit.move(110,?100);PwdEdit.resize(200,?30);PwdEdit.setEchoMode(QLineEdit::Password);Verification.move(50,?150);Verification.resize(110,?30);Verification.setText("Verification?Code:?");VerificationEdit.move(160,?150);VerificationEdit.resize(80,?30);B_Login.setText("Login");B_Login.move(110,?200);B_Login.resize(80,?30);B_Cancel.setText("Cancel");B_Cancel.move(230,?200);B_Cancel.resize(80,?30);setWindowTitle("Login?Window");setFixedSize(400,?300);//生成偽隨機種子qsrand(QTime::currentTime().second()?*?1000?+?QTime::currentTime().msec());m_colors?=?getColors();m_verification?=?getVerificationCode();connect(&B_Login,?SIGNAL(clicked()),?this,?SLOT(Login()));connect(&B_Cancel,?SIGNAL(clicked()),?this,?SLOT(Cancel()));connect(&m_timer,?SIGNAL(timeout()),?this,?SLOT(onTimeOut()));m_timer.start(500); }void?LoginDialog::onTimeOut() {qsrand(QTime::currentTime().second()?*?1000?+?QTime::currentTime().msec());m_colors?=?getColors();update(); }QString?LoginDialog::getUser() {return?m_user; }QString?LoginDialog::getPwd() {return?m_pwd; }void?LoginDialog::Login() {qDebug()?<<?"login";QString?verif?=?VerificationEdit.text().replace("?",?"");if(m_verification.toLower()?==?verif.toLower()){m_user?=?UserEdit.text().trimmed();m_pwd?=?PwdEdit.text();if(!(m_user.isEmpty()?||?m_pwd.isEmpty())){done(Accepted);}else{QMessageBox?mb(this);mb.setWindowTitle("Warning?Message");mb.setIcon(QMessageBox?::Warning);mb.setText("User?or?PassWord?can't?empty!?\nPlease?check?your?username?or?password!");mb.setStandardButtons(QMessageBox::Ok);mb.exec();}}else{QMessageBox::critical(this,?"Verification?Code?Error",?"Verification?Code?Error!\nPlease?Enter?Again.",?QMessageBox::Ok);VerificationEdit.selectAll();} }void?LoginDialog::Cancel() {qDebug()?<<?"cancel";done(Rejected);}void?LoginDialog::paintEvent(QPaintEvent?*event) {QPainter?painter(this);//填充驗證碼繪制矩形painter.fillRect(245,?150,?100,?30,?Qt::white);painter.setFont(QFont("Comic?Sans?MS",?12));//繪制驗證碼for(int?i?=?0;?i?<?4;?i++){painter.setPen(m_colors[i]);painter.drawText(245?+?25*i,?150,?25,?30,?Qt::AlignCenter,?QString(m_verification[i]));}//繪制噪點for(int?i=0;?i<150;?i++){painter.setPen(m_colors[i%4]);painter.drawPoint(245?+?qrand()?%?99,?150?+?qrand()?%?29);} }Qt::GlobalColor*?LoginDialog::getColors() {static?Qt::GlobalColor?colors[4];for(int?i=0;?i<4;?i++){colors[i]?=?static_cast<Qt::GlobalColor>(2?+?qrand()?%?16);}return?colors; } //獲取驗證碼 QString?LoginDialog::getVerificationCode() {QString?ret?=?"";for(int?i?=?0;?i?<?4;?i++){int?c?=?(qrand()?%?2)???'a'?:?'A';ret?+=?static_cast<QChar>(c?+?qrand()?%?26);}return?ret; } //雙擊驗證碼繪制矩形區域，生成新的驗證碼 void?LoginDialog::mouseDoubleClickEvent(QMouseEvent?*event) {if(QRect(245,?150,?100,?30).contains(event->pos())){m_verification?=?getVerificationCode();repaint();} }LoginDialog::~LoginDialog() { }

????Main.cpp文件：

#include?"Widget.h" #include?<QApplication> #include?"LoginDialog.h" #include?<QDebug>int?main(int?argc,?char?*argv[]) {QApplication?a(argc,?argv);QWidget?w;LoginDialog?dialog(&w);dialog.show();if(dialog.exec()?==?QDialog::Accepted){qDebug()?<<"User:"?<<?dialog.getUser();qDebug()?<<?"PassWord:"?<<?dialog.getPwd();}return?a.exec(); }

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代碼見附件

轉載于:https://blog.51cto.com/9291927/1890686

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