在建構函式中定義 一個QTextEdit物件：

m_pText = new QTextEdit(this);

實現函式如下：

QString fileName = QFileDialog::getOpenFileName(this,tr("Open a File"),".",tr("Text File(*.txt)）);
 if(fileName.length() == 0)
         QMessageBox::information(this,tr("Text Files"),tr("You have not open any file"));
 else
 {
        QDir *pDir = new QDir(".");
        QString fileDir = pDir->filePath(fileName);

        QFile file(fileName);
        if (!file.open(QIODevice::ReadWrite)) 
              return;
        QTextStream out(&file);
        while(!file.atEnd())
       {
              m_pText->setText(out.readAll());
       }
 }