嵌入式Qt 实现用户界面与业务逻辑分离_qt 界面与操作逻辑怎么分离

一.基本程序框架一般包含

二.框架的基本设计原则

三.用户界面与业务逻辑的交互

 四.代码实现计算器用户界面与业务逻辑

ICalculator.h

#ifndef _ICALCULATOR_H_
#define _ICALCULATOR_H_
 
#include <QString>
 
class ICalculator
{
public:
    virtual bool expression(const QString& exp) = 0;
    virtual QString result() = 0;
};
 
#endif

QCalculator.h

#ifndef _QCALCULATOR_H_
#define _QCALCULATOR_H_
 
#include "QCalculatorUI.h"
#include "QCalculatorDec.h"
 
class QCalculator
{
protected:
    QCalculatorUI* m_ui;
    QCalculatorDec m_cal;
 
    QCalculator();
    bool construct();
public:
    static QCalculator* NewInstance();
    void show();
    ~QCalculator();
};
 
#endif // QCALCULATOR_H

QCalculator.cpp

#include "QCalculator.h"
 
QCalculator::QCalculator()
{
}
 
bool QCalculator::construct()
{
    m_ui = QCalculatorUI::NewInstance();
 
    if( m_ui != NULL )
    {
        m_ui->setCalculator(&m_cal);
    }
 
    return (m_ui != NULL);
}
 
QCalculator* QCalculator::NewInstance()
{
    QCalculator* ret = new QCalculator();
 
    if( (ret == NULL) || !ret->construct() )
    {
        delete ret;
        ret = NULL;
    }
 
    return ret;
}
 
 
void QCalculator::show()
{
    m_ui->show();
}
 
QCalculator::~QCalculator()
{
    delete m_ui;
}

QCalculatorDec.h

#ifndef _CALCULATORCORE_H_
#define _CALCULATORCORE_H_
 
#include <QString>
#include <QStack>
#include <QQueue>
 
#include "ICalculator.h"
 
class QCalculatorDec : public ICalculator
{
protected:
    QString m_exp;
    QString m_result;
 
    bool isDigitOrDot(QChar c);
    bool isSymbol(QChar c);
    bool isSign(QChar c);
    bool isNumber(QString s);
    bool isOperator(QString s);
    bool isLeft(QString s);
    bool isRight(QString s);
    int priority(QString s);
    bool match(QQueue<QString>& exp);
    QString calculate(QQueue<QString>& exp);
    QString calculate(QString l, QString op, QString r);
    bool transform(QQueue<QString>& exp, QQueue<QString>& output);
    QQueue<QString> split(const QString& exp);
public:
    QCalculatorDec();
    ~QCalculatorDec();
    bool expression(const QString& exp);
    QString expression();
    QString result();
};
 
#endif

 QCalculatorDec.cpp

#include "QCalculatorDec.h"
 
QCalculatorDec::QCalculatorDec()
{
    m_exp = "";
    m_result = "";
}
 
QCalculatorDec::~QCalculatorDec()
{
 
}
 
bool QCalculatorDec::isDigitOrDot(QChar c)
{
    return (('0' <= c) && (c <= '9')) || (c == '.');
}
 
bool QCalculatorDec::isSymbol(QChar c)
{
    return isOperator(c) || (c == '(') || (c == ')');
}
 
bool QCalculatorDec::isSign(QChar c)
{
    return (c == '+') || (c == '-');
}
 
bool QCalculatorDec::isNumber(QString s)
{
    bool ret = false;
 
    s.toDouble(&ret);
 
    return ret;
}
 
bool QCalculatorDec::isOperator(QString s)
{
    return (s == "+") || (s == "-") || (s == "*") || (s == "/");
}
 
bool QCalculatorDec::isLeft(QString s)
{
    return (s == "(");
}
 
bool QCalculatorDec::isRight(QString s)
{
    return (s == ")");
}
 
int QCalculatorDec::priority(QString s)
{
    int ret = 0;
 
    if( (s == "+") || (s == "-") )
    {
        ret = 1;
    }
 
    if( (s == "*") || (s == "/") )
    {
        ret = 2;
    }
 
    return ret;
}
 
bool QCalculatorDec::expression(const QString& exp)
{
    bool ret = false;
    QQueue<QString> spExp = split(exp);
    QQueue<QString> postExp;
 
    m_exp = exp;
 
    if( transform(spExp, postExp) )
    {
        m_result = calculate(postExp);
 
        ret = (m_result != "Error");
    }
    else
    {
        m_result = "Error";
    }
 
 
    return ret;
}
 
QString QCalculatorDec::result()
{
    return m_result;
}
 
QQueue<QString> QCalculatorDec::split(const QString& exp)
{
    QQueue<QString> ret;
    QString num = "";
    QString pre = "";
 
    for(int i=0; i<exp.length(); i++)
    {
        if( isDigitOrDot(exp[i]) )
        {
            num += exp[i];
            pre = exp[i];
        }
        else if( isSymbol(exp[i]) )
        {
            if( !num.isEmpty() )
            {
                ret.enqueue(num);
 
                num.clear();
            }
 
            if( isSign(exp[i]) && ((pre == "") || (pre == "(") || isOperator(pre)) )
            {
                num += exp[i];
            }
            else
            {
                ret.enqueue(exp[i]);
            }
 
            pre = exp[i];
        }
    }
 
    if( !num.isEmpty() )
    {
        ret.enqueue(num);
    }
 
    return ret;
}
 
bool QCalculatorDec::match(QQueue<QString>& exp)
{
    bool ret = true;
    int len = exp.length();
    QStack<QString> stack;
 
    for(int i=0; i<len; i++)
    {
        if( isLeft(exp[i]) )
        {
            stack.push(exp[i]);
        }
        else if( isRight(exp[i]) )
        {
            if( !stack.isEmpty() && isLeft(stack.top()) )
            {
                stack.pop();
            }
            else
            {
                ret = false;
                break;
            }
        }
    }
 
    return ret && stack.isEmpty();
}
 
bool QCalculatorDec::transform(QQueue<QString>& exp, QQueue<QString>& output)
{
    bool ret = match(exp);
    QStack<QString> stack;
 
    output.clear();
 
    while( ret && !exp.isEmpty() )
    {
        QString e = exp.dequeue();
 
        if( isNumber(e) )
        {
            output.enqueue(e);
        }
        else if( isOperator(e) )
        {
            while( !stack.isEmpty() && (priority(e) <= priority(stack.top())) )
            {
                output.enqueue(stack.pop());
            }
 
            stack.push(e);
        }
        else if( isLeft(e) )
        {
            stack.push(e);
        }
        else if( isRight(e) )
        {
            while( !stack.isEmpty() && !isLeft(stack.top()) )
            {
                output.enqueue(stack.pop());
            }
 
            if( !stack.isEmpty() )
            {
                stack.pop();
            }
        }
        else
        {
            ret = false;
        }
    }
 
    while( !stack.isEmpty() )
    {
        output.enqueue(stack.pop());
    }
 
    if( !ret )
    {
        output.clear();
    }
 
    return ret;
}
 
QString QCalculatorDec::calculate(QString l, QString op, QString r)
{
    QString ret = "Error";
 
    if( isNumber(l) && isNumber(r) )
    {
        double lp = l.toDouble();
        double rp = r.toDouble();
 
        if( op == "+" )
        {
            ret.sprintf("%f", lp + rp);
        }
        else if( op == "-" )
        {
            ret.sprintf("%f", lp - rp);
        }
        else if( op == "*" )
        {
            ret.sprintf("%f", lp * rp);
        }
        else if( op == "/" )
        {
            const double P = 0.000000000000001;
 
            if( (-P < rp) && (rp < P) )
            {
                ret = "Error";
            }
            else
            {
                ret.sprintf("%f", lp / rp);
            }
 
        }
        else
        {
            ret = "Error";
        }
    }
 
    return ret;
}
 
QString QCalculatorDec::calculate(QQueue<QString>& exp)
{
    QString ret = "Error";
    QStack<QString> stack;
 
    while( !exp.isEmpty() )
    {
        QString e = exp.dequeue();
 
        if( isNumber(e) )
        {
            stack.push(e);
        }
        else if( isOperator(e) )
        {
            QString rp = !stack.isEmpty() ? stack.pop() : "";
            QString lp = !stack.isEmpty() ? stack.pop() : "";
            QString result = calculate(lp, e, rp);
 
            if( result != "Error" )
            {
                stack.push(result);
            }
            else
            {
                break;
            }
        }
        else
        {
            break;
        }
    }
 
    if( exp.isEmpty() && (stack.size() == 1) && isNumber(stack.top()) )
    {
        ret = stack.pop();
    }
 
    return ret;
}

QCalculatorUI.h

#ifndef _QCALCULATORUI_H_
#define _QCALCULATORUI_H_
 
#include <QWidget>
#include <QLineEdit>
#include <QPushButton>
 
#include "ICalculator.h"
 
class QCalculatorUI : public QWidget
{
    Q_OBJECT
private:
    QLineEdit* m_edit;
    QPushButton* m_buttons[20];
    ICalculator* m_cal;
 
    QCalculatorUI();
    bool construct();
private slots:
    void onButtonClicked();
public:
    static QCalculatorUI* NewInstance();
    void show();
    void setCalculator(ICalculator* cal);
    ICalculator* getCalculator();
    ~QCalculatorUI();
};
 
#endif

QCalculatorUI.cpp

#include "QCalculatorUI.h"
#include <QDebug>
 
QCalculatorUI::QCalculatorUI() : QWidget(NULL, Qt::WindowCloseButtonHint)
{
    m_cal = NULL;
}
 
bool QCalculatorUI::construct()
{
    bool ret = true;
    const char* btnText[20] =
    {
        "7", "8", "9", "+", "(",
        "4", "5", "6", "-", ")",
        "1", "2", "3", "*", "<-",
        "0", ".", "=", "/", "C",
    };
 
    m_edit = new QLineEdit(this);
 
    if( m_edit != NULL )
    {
        m_edit->move(10, 10);
        m_edit->resize(240, 30);
        m_edit->setReadOnly(true);
        m_edit->setAlignment(Qt::AlignRight);
    }
    else
    {
        ret = false;
    }
 
    for(int i=0; (i<4) && ret; i++)
    {
        for(int j=0; (j<5) && ret; j++)
        {
            m_buttons[i*5 + j] = new QPushButton(this);
 
            if( m_buttons[i*5 + j] != NULL )
            {
                m_buttons[i*5 + j]->resize(40, 40);
                m_buttons[i*5 + j]->move(10 + (10 + 40)*j, 50 + (10 + 40)*i);
                m_buttons[i*5 + j]->setText(btnText[i*5 + j]);
 
                connect(m_buttons[i*5 + j], SIGNAL(clicked()), this, SLOT(onButtonClicked()));
            }
            else
            {
                ret = false;
            }
        }
    }
 
    return ret;
}
 
QCalculatorUI* QCalculatorUI::NewInstance()
{
    QCalculatorUI* ret = new QCalculatorUI();
 
    if( (ret == NULL) || !ret->construct() )
    {
        delete ret;
        ret = NULL;
    }
 
    return ret;
}
 
void QCalculatorUI::show()
{
    QWidget::show();
 
    setFixedSize(width(), height());
}
 
void QCalculatorUI::onButtonClicked()
{
    QPushButton* btn = dynamic_cast<QPushButton*>(sender());
 
    if( btn != NULL )
    {
        QString clickText = btn->text();
 
        if( clickText == "<-" )
        {
            QString text = m_edit->text();
 
            if( text.length() > 0 )
            {
                text.remove(text.length()-1, 1);
 
                m_edit->setText(text);
            }
        }
        else if( clickText == "C" )
        {
            m_edit->setText("");
        }
        else if( clickText == "=" )
        {
            if( m_cal != NULL )
            {
                m_cal->expression(m_edit->text());
                m_edit->setText(m_cal->result());
            }
        }
        else
        {
            m_edit->setText(m_edit->text() + clickText);
        }
    }
}
 
void QCalculatorUI::setCalculator(ICalculator* cal)
{
    m_cal = cal;
}
 
ICalculator* QCalculatorUI::getCalculator()
{
    return m_cal;
}
 
QCalculatorUI::~QCalculatorUI()
{
 
}

main.cpp

#include <QApplication>
 
#include "QCalculator.h"
 
int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    QCalculator* cal = QCalculator::NewInstance();
    int ret = -1;
 
    if( cal != NULL )
    {
        cal->show();
 
        ret = a.exec();
 
        delete cal;
    }
 
    return ret;
}