curl断点续载

摘自http://blog.csdn.net/zmy12007/article/details/37157297

摘自http://www.linuxidc.com/Linux/2014-10/107509.htm

curl断点续传，下载过程中关闭控制台，然后重新启动，又会接着下载

#include "stdafx.h"
#include <io.h>
#include "curl/curl.h"
#include <string>/*注意包含这个头文件后必须把share.h重命名一下，可能是stl里面也有这个头文件，比如curl_share.h,然后把包含到的地方替换一下*/

#include "curl/easy.h"

using namespace std;

static size_t downLoadPackage(void *ptr, size_t size, size_t nmemb, void *userdata)
{
    FILE *fp = (FILE*)userdata;
    size_t written = fwrite(ptr, size, nmemb, fp);
    return written;
}

int assetsManagerProgressFunc(void *ptr, double totalToDownload, double nowDownloaded, double totalToUpLoad, double nowUpLoaded)
{
    static int percent = 0;
    int tmp = 0;
    long localLen = *(long*)ptr;
    if ( totalToDownload > 0 )
    {
        tmp = (int)((nowDownloaded + (double)localLen) / (totalToDownload + (double)localLen) * 100);
    }

    printf("下载进度%0d%%
", tmp);
    return 0;
}

long GetLocalFileLenth(const char* fileName)
{
    char strTemp[256] = {0};
    strcpy_s(strTemp,fileName);
    FILE* fp = fopen(strTemp, "rb");
    if(fp != NULL)
    {
        long localLen = _filelength(_fileno(fp));
        fclose(fp);
        return localLen;
    }
    return 0;
}

/************************************************************************/
/* 获取要下载的远程文件的大小                                            */
/************************************************************************/
long getDownloadFileLenth(const char *url){
    long downloadFileLenth = 0;
    CURL *handle = curl_easy_init();
    curl_easy_setopt(handle, CURLOPT_URL, url);
    curl_easy_setopt(handle, CURLOPT_HEADER, 1);    //只需要header头
    curl_easy_setopt(handle, CURLOPT_NOBODY, 1);    //不需要body
    if (curl_easy_perform(handle) == CURLE_OK)
    {
        curl_easy_getinfo(handle, CURLINFO_CONTENT_LENGTH_DOWNLOAD, &downloadFileLenth);
    }
    else
    {
        downloadFileLenth = -1;
    }
    return downloadFileLenth;
}

bool downLoad(void *_curl, std::string _packageUrl, std::string _storagePath, std::string fileName )
{
    // Create a file to save package.
    const string outFileName = _storagePath + fileName;
    //================断点续载===================
    long localLen = GetLocalFileLenth(outFileName.c_str());

    FILE *fp = fopen(outFileName.c_str(), "a+b");
    if (! fp)
    {
        return false;
    }
    fseek(fp, 0, SEEK_END);

    // Download pacakge
    CURLcode res;
    curl_easy_setopt(_curl, CURLOPT_URL, _packageUrl.c_str());
    curl_easy_setopt(_curl, CURLOPT_WRITEFUNCTION, downLoadPackage);
    curl_easy_setopt(_curl, CURLOPT_WRITEDATA, fp);
    curl_easy_setopt(_curl, CURLOPT_NOPROGRESS, false);
    curl_easy_setopt(_curl, CURLOPT_PROGRESSFUNCTION, assetsManagerProgressFunc);
    curl_easy_setopt(_curl, CURLOPT_NOSIGNAL, 1L);
    curl_easy_setopt(_curl, CURLOPT_LOW_SPEED_LIMIT, 1L);
    curl_easy_setopt(_curl, CURLOPT_LOW_SPEED_TIME, 5L);

    curl_easy_setopt(_curl, CURLOPT_HEADER, 0L);
    curl_easy_setopt(_curl, CURLOPT_NOBODY, 0L);
    curl_easy_setopt(_curl, CURLOPT_FOLLOWLOCATION, 1L);
    curl_easy_setopt(_curl, CURLOPT_RESUME_FROM, localLen);

    curl_easy_setopt(_curl, CURLOPT_PROGRESSDATA, &localLen);



    res = curl_easy_perform(_curl);
    curl_easy_cleanup(_curl);
    if (res != 0)
    {
        fclose(fp);
        return false;
    }

    fclose(fp);
    return true;
}

int _tmain(int argc, _TCHAR* argv[])
{
    CURL* _curl = curl_easy_init();
    if (! _curl)
    {
        return 0;
    }

    downLoad(_curl, "http://ardownload.adobe.com/pub/adobe/reader/win/11.x/11.0.01/en_US/AdbeRdr11001_en_US.exe", "./", "AdbeRdr11001_en_US.exe");
    //downLoad(_curl, "http://localhost/MyWebServer.rar", "./", "MyWebServer.rar");
    getchar();
    return 0;
}