【轉】c++ http下載檔案

#include <afx.h>
#include <afxinet.h>
#define RECVPACK_SIZE 2048
bool DownloadSaveFiles(char* url,char *strSaveFile) {//下載檔案並儲存為新檔名
    bool ret=false;
    CInternetSession Sess("lpload");
    Sess.SetOption(INTERNET_OPTION_CONNECT_TIMEOUT     , 2000); //2秒的連線超時
    Sess.SetOption(INTERNET_OPTION_SEND_TIMEOUT        , 2000); //2秒的傳送超時
    Sess.SetOption(INTERNET_OPTION_RECEIVE_TIMEOUT     , 2000); //2秒的接收超時
    Sess.SetOption(INTERNET_OPTION_DATA_SEND_TIMEOUT   , 2000); //2秒的傳送超時
    Sess.SetOption(INTERNET_OPTION_DATA_RECEIVE_TIMEOUT, 2000); //2秒的接收超時
    DWORD dwFlag = INTERNET_FLAG_TRANSFER_BINARY|INTERNET_FLAG_DONT_CACHE|INTERNET_FLAG_RELOAD ;

    CHttpFile* cFile   = NULL;
    char      *pBuf    = NULL;
    int        nBufLen = 0   ;
    do {
        try{
            cFile = (CHttpFile*)Sess.OpenURL(url,1,dwFlag);
            DWORD dwStatusCode;
            cFile->QueryInfoStatusCode(dwStatusCode);
            if (dwStatusCode == HTTP_STATUS_OK) {
                //查詢檔案長度
                DWORD nLen=0;
                cFile->QueryInfo(HTTP_QUERY_CONTENT_LENGTH, nLen);
                //CString strFilename = GetFileName(url,TRUE);
                nBufLen=nLen;
                if (nLen <= 0) break;//

                //分配接收資料快取
                pBuf = (char*)malloc(nLen+8);
                ZeroMemory(pBuf,nLen+8);

                char *p=pBuf;
                while (nLen>0) {
                    //每次下載8K
                    int n = cFile->Read(p,(nLen<RECVPACK_SIZE)?nLen:RECVPACK_SIZE);
                    //接收完成退出迴圈
                    if (n <= 0) break;//
                    //接收快取後移
                    p+= n ;
                    //剩餘長度遞減
                    nLen -= n ;
                }

                //如果未接收完中斷退出
                if (nLen != 0) break;

                //接收成功儲存到檔案

                CFile file(strSaveFile, CFile::modeCreate | CFile::modeWrite);
                file.Write(pBuf,nBufLen);
                file.Close();
                ret = true;
            }
        } catch(...) {
            break;//
        }
    } while(0);

    //釋放快取
    if (pBuf) {
        free(pBuf);
        pBuf=NULL;
        nBufLen = 0 ;
    }

    //關閉下載連線
    if (cFile) {
        cFile->Close();
        Sess.Close();
        delete cFile;
    }
    return ret;
}
int main() {
    DownloadSaveFiles("http://www.nirsoft.net/utils/nircmd.zip","d:\\cppdld_nircmd.zip");
    return 0;
}

http://bbs.csdn.net/topics/390052882