Qt操作windows注册表例程

实现效果 修改注册表， 将特定后缀名的文件和应用程序关联，当打开该后缀名对应的文件时会启动对应的应用程序

运行效果

关键代码

=============main.cpp====================
#include "mainwidget.h"
#include <QApplication>

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    MainWidget w;
    w.show();

    for(int i=0; i<argc; i++)
    {
        w.appendText(argv[i]);
    }

    if(argc==2)
    {
        w.openFile(argv[1]);
    }

    return a.exec();
}

=============mainwidget.cpp================
#include "mainwidget.h"
#include "ui_mainwidget.h"
#include <QFile>
#include <QTextStream>
#include <QSettings>
#include <QDebug>

MainWidget::MainWidget(QWidget *parent) :
    QWidget(parent),
    ui(new Ui::MainWidget)
{
    ui->setupUi(this);
    ui->textEdit->setLineWrapMode(QTextEdit::NoWrap);
    ui->textOut->setLineWrapMode(QTextEdit::NoWrap);
    this->setWindowTitle("Tegistry Test");
}

MainWidget::~MainWidget()
{
    delete ui;
}

void MainWidget::openFile(const QString &filePath)
{
    ui->textOut->append(QString("openFile filePath=")+filePath);
    QFile file(filePath);
    if(file.open(QFile::ReadOnly | QFile::Text))
    {
        QTextStream ts(&file);
        ui->textEdit->setText(ts.readAll());
        file.close();
    }
}

void MainWidget::appendText(const QString &text)
{
    ui->textOut->append(text);
}

void MainWidget::on_buttonWrite_clicked()
{
    QSettings settings("HKEY_CLASSES_ROOT\\.water", QSettings::NativeFormat);
    settings.setValue(".", "waterpro");

    QSettings settings2("HKEY_CLASSES_ROOT\\waterpro\\shell\\open\\command", QSettings::NativeFormat);
    settings2.setValue(".", "\""+QApplication::applicationFilePath().replace("/", "\\")+"\" \"%1\"");

    //注意，读写注册表时不需要调用sync函数

    appendText("on_buttonWrite_clicked default="+settings2.value(".").toString());
    appendText("Setted!");
}

void MainWidget::on_buttonRemove_clicked()
{
    QSettings settings("HKEY_CLASSES_ROOT\\.water", QSettings::NativeFormat);
    settings.clear();

    QSettings settings2("HKEY_CLASSES_ROOT\\waterpro", QSettings::NativeFormat);
    settings2.clear();

    //注意，读写注册表时不需要调用sync函数

    appendText("Removed!");
}

（4）参考资料 http://blog.csdn.net/arvon2012/article/details/7818909