curl断点续传

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%%\r", 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;
}