使用 WinHttp 实现文件下载

 #include <Windows.h>
 #include <Winhttp.h>
 #pragma comment(lib,"Winhttp.lib")

 typedef struct _URL_INFO
 {
     WCHAR szScheme[];
     WCHAR szHostName[];
     WCHAR szUserName[];
     WCHAR szPassword[];
     WCHAR szUrlPath[];
     WCHAR szExtraInfo[];
 }URL_INFO, *PURL_INFO;

 int WINAPI wWinMain( HINSTANCE hInstance, HINSTANCE hPrevInstance, LPWSTR lpCmdLine, int nShowCmd )
 {
     URL_INFO url_info = {};
     URL_COMPONENTSW url = {};
     url.dwStructSize = sizeof(url);
     url.lpszExtraInfo = url_info.szExtraInfo;
     url.lpszHostName = url_info.szHostName;
     url.lpszPassword = url_info.szPassword;
     url.lpszScheme = url_info.szScheme;
     url.lpszUrlPath = url_info.szUrlPath;
     url.lpszUserName = url_info.szUserName;

     url.dwExtraInfoLength =
         url.dwHostNameLength =
         url.dwPasswordLength =
         url.dwSchemeLength =
         url.dwUrlPathLength =
         url.dwUserNameLength = ;

     WinHttpCrackUrl(L"http://www.pediy.com/tools/Debuggers/ollydbg/OllyICE.rar", , ICU_ESCAPE, &url);

     // 创建一个会话
     HINTERNET hSession = WinHttpOpen(NULL, WINHTTP_ACCESS_TYPE_NO_PROXY, NULL, NULL, );
     BYTE *pBuffer = NULL;
     DWORD dwReadBytes, dwSizeDW = sizeof(dwSizeDW), dwContentSize, dwIndex = ;
     // 创建一个连接
     HINTERNET hConnect = WinHttpConnect(hSession, url.lpszHostName, url.nPort, );
     // 创建一个请求，先查询内容的大小
     HINTERNET hRequest = WinHttpOpenRequest(hConnect, L"HEAD", url.lpszUrlPath, L"HTTP/1.1", WINHTTP_NO_REFERER, WINHTTP_DEFAULT_ACCEPT_TYPES, WINHTTP_FLAG_REFRESH);
     WinHttpSendRequest(hRequest, WINHTTP_NO_ADDITIONAL_HEADERS, , WINHTTP_NO_REQUEST_DATA, , , );
     WinHttpReceiveResponse(hRequest, );
     WinHttpQueryHeaders(hRequest, WINHTTP_QUERY_CONTENT_LENGTH|WINHTTP_QUERY_FLAG_NUMBER, NULL, &dwContentSize, &dwSizeDW, &dwIndex);
     WinHttpCloseHandle(hRequest);

     // 创建一个请求，获取数据
     hRequest = WinHttpOpenRequest(hConnect, L"GET", url.lpszUrlPath, L"HTTP/1.1", WINHTTP_NO_REFERER, WINHTTP_DEFAULT_ACCEPT_TYPES, WINHTTP_FLAG_REFRESH);
     WinHttpSendRequest(hRequest, WINHTTP_NO_ADDITIONAL_HEADERS, , WINHTTP_NO_REQUEST_DATA, , , );
     WinHttpReceiveResponse(hRequest, );
     pBuffer = new BYTE[dwContentSize];
     ZeroMemory(pBuffer, dwContentSize);
     WinHttpReadData(hRequest, pBuffer, dwContentSize, &dwReadBytes);

     HANDLE hFile = CreateFileW(L"c:\\ollydbg.rar", GENERIC_WRITE, FILE_SHARE_READ, NULL, CREATE_ALWAYS, FILE_ATTRIBUTE_NORMAL, NULL);
     WriteFile(hFile, pBuffer, dwContentSize, &dwReadBytes, NULL);
     CloseHandle(hFile);

     delete pBuffer;

     WinHttpCloseHandle(hRequest);
     WinHttpCloseHandle(hConnect);
     WinHttpCloseHandle(hSession);

     return ;
 }