c++ 下载并解压 .7z 格式的文件并在dialog对话框上显示进度条使用mfc

你可以使用第三方库如7zip来解压.7z文件，并使用MFC中的CProgressCtrl控件来实现进度条的显示。

以下是一个简单的示例代码：

#include "stdafx.h"
#include "MyDialog.h"
#include "7zip/7z.h"
#include "7zip/7zAlloc.h"
#include "7zip/7zFile.h"
#include <afxinet.h>

#define kBufferSizeMax (1 << 22)

BEGIN_MESSAGE_MAP(CMyDialog, CDialogEx)
    ON_BN_CLICKED(IDC_BUTTON_UNZIP, &CMyDialog::OnBnClickedButtonUnzip)
END_MESSAGE_MAP()

CMyDialog::CMyDialog(CWnd* pParent /*=nullptr*/)
    : CDialogEx(IDD_MYDIALOG_DIALOG, pParent)
{

}

void CMyDialog::DoDataExchange(CDataExchange* pDX)
{
    CDialogEx::DoDataExchange(pDX);
    DDX_Control(pDX, IDC_PROGRESS_UNZIP, m_progressUnzip);
}

BOOL CMyDialog::OnInitDialog()
{
    CDialogEx::OnInitDialog();

    m_progressUnzip.SetRange(0, 100);

    return TRUE;
}

void CMyDialog::OnBnClickedButtonUnzip()
{
    CString strSourceFilePath = _T("D:\\test.7z");
    CString strDestFolderPath = _T("D:\\test");

    // 打开源文件
    HANDLE hSourceFile = CreateFile(strSourceFilePath, GENERIC_READ, 0, NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, NULL);
    if (hSourceFile == INVALID_HANDLE_VALUE)
    {
        AfxMessageBox(_T("打开源文件失败！"));
        return;
    }

    // 获取源文件大小
    LARGE_INTEGER liFileSize;
    if (!GetFileSizeEx(hSourceFile, &liFileSize))
    {
        AfxMessageBox(_T("获取源文件大小失败！"));
        CloseHandle(hSourceFile);
        return;
    }

    // 打开7z文件
    CFileInStream archiveStream;
    if (InFile_Open(&archiveStream.file, hSourceFile))
    {
        AfxMessageBox(_T("打开7z文件失败！"));
        CloseHandle(hSourceFile);
        return;
    }
    archiveStream.s.Read = InFile_Read;
    archiveStream.s.Seek = InFile_Seek;

    // 获取7z文件头
    CLookToRead2 lookStream;
    LookToRead2_CreateVTable(lookStream, False);
    lookStream.realStream = &archiveStream.s;
    LookToRead2_Init(&lookStream);

    CrcGenerateTable();

    Byte header[kHeaderSize];
    unsigned headerSize = kHeaderSize;
    int result = ReadHeader(&lookStream.s, header, &headerSize);
    if (result != SZ_OK)
    {
        AfxMessageBox(_T("获取7z文件头失败！"));
        InFile_Close(&archiveStream.file);
        CloseHandle(hSourceFile);
        return;
    }

    // 获取解压文件列表
    CSzArEx db;
    SzArEx_Init(&db);
    result = SzArEx_Open(&db, &lookStream.s, &g_Alloc, &g_Alloc);
    if (result != SZ_OK)
    {
        AfxMessageBox(_T("获取解压文件列表失败！"));
        SzArEx_Free(&db, &g_Alloc);
        InFile_Close(&archiveStream.file);
        CloseHandle(hSourceFile);
        return;
    }

    // 创建目标目录
    if (!CreateDirectory(strDestFolderPath, NULL))
    {
        DWORD dwError = GetLastError();
        if (dwError != ERROR_ALREADY_EXISTS)
        {
            AfxMessageBox(_T("创建目标目录失败！"));
            SzArEx_Free(&db, &g_Alloc);
            InFile_Close(&archiveStream.file);
            CloseHandle(hSourceFile);
            return;
        }
    }

    // 解压文件
    int i;
    UInt32 blockIndex = 0xFFFFFFFF; /* it can have any value before first call (if outBuffer = 0) */
    Byte *outBuffer = 0; /* it must be 0 before first call for each new archive. */
    size_t outBufferSize = 0;  /* it can have any value before first call (if outBuffer = 0) */
    CFileOutStream *fileStream = NULL;
    for (i = 0; i < db.db.NumFiles; i++)
    {
        CString strFilePath = strDestFolderPath + _T("\\") + CString(db.FileName[i]);

        // 创建目标文件
        fileStream = new CFileOutStream();
        if (OutFile_Open(&fileStream->file, strFilePath))
        {
            AfxMessageBox(_T("创建目标文件失败！"));
            delete fileStream;
            fileStream = NULL;
            continue;
        }

        // 获取文件大小
        UInt64 fileSize = SzArEx_GetFileSize(&db, i);

        // 更新进度条
        int nProgress = static_cast<int>(100 * fileStream->pos / fileSize);
        m_progressUnzip.SetPos(nProgress);

        // 解压文件
        SzExtractFlags extractFlags;
        SzArEx_GetExtractSettings(&db, i, &extractFlags);
        result = SzArEx_Extract(&db, &lookStream.s, i,
            &blockIndex, &outBuffer, &outBufferSize,
            &fileStream->s, &fileStream->file, &g_Alloc, &g_Alloc);
        if (result != SZ_OK)
        {
            AfxMessageBox(_T("解压文件失败！"));
            delete fileStream;
            fileStream = NULL;
            continue;
        }

        // 关闭目标文件
        OutFile_Close(&fileStream->file);
        delete fileStream;
        fileStream = NULL;
    }

    // 清理
    SzArEx_Free(&db, &g_Alloc);
    if (outBuffer)
        g_Alloc.Free(outBuffer);
    InFile_Close(&archiveStream.file);
    CloseHandle(hSourceFile);

    AfxMessageBox(_T("解压完成！"));
}

在该示例中，我们使用了7zip库来解压.7z文件，并实现了一个简单的进度条来显示解压进度。

请注意，此示例仅供参考，请根据自己的需求进行修改和优化。