c++ - 如何在 C/C++ 中使用 WinHTTP 下载文件？

Question

我知道如何下载 html/txt 页面。例如:

//Variables 
DWORD dwSize = 0;
DWORD dwDownloaded = 0;
LPSTR pszOutBuffer;
vector <string>  vFileContent;
BOOL  bResults = FALSE;
HINTERNET  hSession = NULL, 
           hConnect = NULL,
           hRequest = NULL;

// Use WinHttpOpen to obtain a session handle.
hSession = WinHttpOpen( L"WinHTTP Example/1.0",  
                        WINHTTP_ACCESS_TYPE_DEFAULT_PROXY,
                        WINHTTP_NO_PROXY_NAME, 
                        WINHTTP_NO_PROXY_BYPASS, 0);

// Specify an HTTP server.
if (hSession)
    hConnect = WinHttpConnect( hSession, L"nytimes.com",
                               INTERNET_DEFAULT_HTTP_PORT, 0);

// Create an HTTP request handle.
if (hConnect)
    hRequest = WinHttpOpenRequest( hConnect, L"GET", L"/ref/multimedia/podcasts.html",
                                   NULL, WINHTTP_NO_REFERER, 
                                   NULL, 
                                   NULL);

// Send a request.
if (hRequest)
    bResults = WinHttpSendRequest( hRequest,
                                   WINHTTP_NO_ADDITIONAL_HEADERS,
                                   0, WINHTTP_NO_REQUEST_DATA, 0, 
                                   0, 0);


// End the request.
if (bResults)
    bResults = WinHttpReceiveResponse( hRequest, NULL);

// Keep checking for data until there is nothing left.
if (bResults)
    do 
    {

        // Check for available data.
        dwSize = 0;
        if (!WinHttpQueryDataAvailable( hRequest, &dwSize))
            printf( "Error %u in WinHttpQueryDataAvailable.\n",
                    GetLastError());

        // Allocate space for the buffer.
        pszOutBuffer = new char[dwSize+1];
        if (!pszOutBuffer)
        {
            printf("Out of memory\n");
            dwSize=0;
        }
        else
        {
            // Read the Data.
            ZeroMemory(pszOutBuffer, dwSize+1);

            if (!WinHttpReadData( hRequest, (LPVOID)pszOutBuffer, 
                                  dwSize, &dwDownloaded))
            {
                printf( "Error %u in WinHttpReadData.\n", 
                        GetLastError());
            }
            else
            {
                        printf("%s", pszOutBuffer);
                            // Data in vFileContent
                vFileContent.push_back(pszOutBuffer);
            }

            // Free the memory allocated to the buffer.
            delete [] pszOutBuffer;
        }

    } while (dwSize>0);


// Report any errors.
if (!bResults)
    printf("Error %d has occurred.\n",GetLastError());

// Close any open handles.
if (hRequest) WinHttpCloseHandle(hRequest);
if (hConnect) WinHttpCloseHandle(hConnect);
if (hSession) WinHttpCloseHandle(hSession);

// Write vFileContent to file
ofstream out("test.txt",ios::binary);
for (int i = 0; i < (int) vFileContent.size();i++)
out << vFileContent[i];
out.close();

当我尝试下载图片时，我只收到文件的第一行，没有任何错误消息。该问题似乎与 WinHttpOpenRequest 函数中的此参数 (ppwszAcceptTypes) 有关。

link text

Answer 1

仅以二进制模式打开 ofstream 不会改变 << 运算符的工作方式 - 它们将始终执行格式化输出。您需要使用流的 write() 函数，它执行无格式输出。