1.软件安装目录保存在注册表中

离线程序自动更新，其本质是替换原来的.dll，.exe等文件，并保持文件名不变，或者新增部分文件。
以下是以同名文件替换为例：
1.首先需要知道软件的安装路径，这个可以在软件运行时，自动保存软件安装路径到注册表指定位置；
2.更新软件读取注册表对应的安装路径；
3.文件的删除与替换。

保存安装路径到注册表

	QString path = QCoreApplication::applicationFilePath();
    path.replace("/", "\\");

   
    QString readPath;
    // #define Reg_MyExe_Path  "HKEY_LOCAL_MACHINE\\SOFTWARE\\MyCompany"
    QSettings* settings = new QSettings(Reg_MyExe_Path, QSettings::NativeFormat);
    QVariant p = settings->value(exeName); // QString exeName = "MyExe";
    if (p.toString().isEmpty())
    {
        settings->setValue(exeName, path);
    }
    delete settings;

读取注册表软件安装目录

	 QString exePth;

    QSettings* settings = new QSettings(Reg_MyExe_Path, QSettings::NativeFormat);
    exePth = settings->value(exeName).toString();
    if (exePth.isEmpty())
    {
        QMessageBox::warning(this, "Warning", "软件更新失败!");
        return;
    }
    delete settings;

    qDebug() << "-----file path: " << exePth;

    QString oldFile, newFile,fname = "123.txt";
    oldFile = QFileInfo(exePth).absolutePath().append("%1%2").arg("/").arg(fname);
    newFile = QFileInfo("testFile/" + fname).absoluteFilePath();

    autoReplaceFile(oldFile, newFile);

测试demo界面

在这里插入图片描述

测试demo.h

#pragma once

#include <QtWidgets/QMainWindow>
#include "ui_testSoftUpdate.h"
#include <qsettings.h>  
#include <QFile>
#include <qfileinfo.h>
#include <qmessagebox.h>

#define Reg_MyExe_Path  "HKEY_LOCAL_MACHINE\\SOFTWARE\\MyCompany"

#if _MSC_VER >= 1600 

#pragma  execution_character_set("utf-8")

#endif
class testSoftUpdate : public QMainWindow
{
    Q_OBJECT

public:
    testSoftUpdate(QWidget *parent = Q_NULLPTR);

private slots:
    void on_btnSave_clicked();
    void on_btnUpdate_clicked();

private:
    Ui::testSoftUpdateClass ui;
    QString exeName = "MyExe";

    void autoReplaceFile(const QString& oldfile, const QString& newfile);
};

测试demo.cpp

#include "testSoftUpdate.h"
#include <qdebug.h>

testSoftUpdate::testSoftUpdate(QWidget *parent)
    : QMainWindow(parent)
{
    ui.setupUi(this);
}

void testSoftUpdate::on_btnSave_clicked()
{
    QString path = QCoreApplication::applicationFilePath();
    path.replace("/", "\\");

   
    QString readPath;
    QSettings* settings = new QSettings(Reg_MyExe_Path, QSettings::NativeFormat);
    QVariant p = settings->value(exeName);
    if (p.toString().isEmpty())
    {
        settings->setValue(exeName, path);
    }
    delete settings;
}
void testSoftUpdate::on_btnUpdate_clicked()
{
    QString exePth;

    QSettings* settings = new QSettings(Reg_MyExe_Path, QSettings::NativeFormat);
    exePth = settings->value(exeName).toString();
    if (exePth.isEmpty())
    {
        QMessageBox::warning(this, "Warning", "软件更新失败!");
        return;
    }
    delete settings;

    qDebug() << "-----file path: " << exePth;

    QString oldFile, newFile,fname = "123.txt";
    oldFile = QFileInfo(exePth).absolutePath().append("%1%2").arg("/").arg(fname);
    newFile = QFileInfo("testFile/" + fname).absoluteFilePath();

    autoReplaceFile(oldFile, newFile);
}

void testSoftUpdate::autoReplaceFile(const QString& oldfile, const QString& newfile)
{

    qDebug() << "-----oldfile path: " << oldfile << ", newfile path : " << newfile;

    QFile f;
    if (f.remove(oldfile))
    {
        QMessageBox::warning(this, "Warning", "请先关闭软件!");
        return;
    }
    _sleep(20);
      

    if (f.copy(newfile, oldfile))
    {
        qDebug() << "-----copy succeed ! --------";
        QMessageBox::information(this, "通知", "软件已更新完成!");
    }
    else
    {
        QMessageBox::warning(this, "Warning", "请先关闭软件!");
    }
}