一步步学Qt,第四天-Qt 建立MainWindow的小小bug处理

一步步学Qt,第四天-Qt 建立MainWindow的小小bug处理

刚写好的小小的记事本,差不多可以使用了,不过在测试中发现了很多的bug,这才一个个的修改了,修改后的实现文件code是:

#include "mainwindow.h"#include "ui_mainwindow.h"#include <QMessageBox>#include <QFileDialog>#include <QTextStream>#include <QTextEdit>#include <QDebug>MainWindow::MainWindow(QWidget *parent) :    QMainWindow(parent),    ui(new Ui::MainWindow){    ui->setupUi(this);   setCentralWidget(ui->textEdit);    //action setting    ui->mainToolBar->addAction(ui->action_New);    ui->mainToolBar->addAction(ui->action_Open);    ui->mainToolBar->addAction(ui->action_Cut);    ui->mainToolBar->addAction(ui->action_About);    //slot setting    connect(ui->action_About,SIGNAL(triggered()),this,SLOT(about()));    connect(ui->action_New,SIGNAL(triggered()),this,SLOT(newFile()));    connect(ui->action_Open,SIGNAL(triggered()),this,SLOT(openFile()));}MainWindow::~MainWindow(){    delete ui;}void MainWindow::about(){    QMessageBox::about(this,tr("About this app"),tr("copyrigth by PowerLinux"));    return;}void MainWindow::newFile(){    int i = fileChanged();    if(i == 1){        int s = QMessageBox::question(this,tr("Asking"),tr("File is changed ,Save it?"),QMessageBox::Ok | QMessageBox::Cancel);        if(s == QMessageBox::Ok){            saveFile();             ui->textEdit->setText("");        }        else{            ui->textEdit->setText("");        }    }    else{            MainWindow *newWin = new MainWindow;                newWin->show();    }}void MainWindow::openFile(){    int i = fileChanged();    if(i == 1){        fileName = QFileDialog::getOpenFileName(this);       QString openfilename = fileName;        if(!fileName.isEmpty())        {            int s = QMessageBox::question(this,tr("Asking"),tr("the old File is changed ,are you sure?"),QMessageBox::Ok | QMessageBox::Cancel);            if(s == QMessageBox::Ok){                saveFile();                                ui->textEdit->setText("");                loadFile(openfilename);            }            if(s == QMessageBox::Cancel){                ui->textEdit->setText("");                loadFile(openfilename);            }        }    }    else{        fileName = QFileDialog::getOpenFileName(this);        if (!fileName.isEmpty())        {            loadFile(fileName);        }    }}void MainWindow::loadFile(QString filename){    QFile file(filename);    if(file.open(QIODevice::ReadOnly | QIODevice::Text)){        QTextStream textStream(&file);        while(!textStream.atEnd()){            ui->textEdit->append(textStream.readLine());        }    }}int MainWindow::fileChanged(){    if(ui->textEdit->document()->isModified()){       return 1;    }    else{        return 0;    }}void MainWindow::saveFile()//! [44] //! [45]{    fileName = QFileDialog::getSaveFileName(this);    if (!fileName.isEmpty()){        QFile file(fileName);        if (!file.open(QFile::WriteOnly | QFile::Text)) {            QMessageBox::warning(this, tr("Application"),                                 tr("Cannot write file %1:\n%2.")                                 .arg(fileName)                                 .arg(file.errorString()));        }        else{            QTextStream out(&file);            out << ui->textEdit->toPlainText();        }    }}

注意code中

   QString openfilename = fileName;

openfilename是一个临时使用的数据,为了是在getOpenFileName的时候不会与在使用saveFile时与对应的fileName不会重复,这样在loadfile就不会出错了.