其实libcurl自带一个应用，很高大上，但是作为范例参考怎么使用libcurl觉得不大适合！还是写一些helloworl的程序的，一目了然......

#include "stdafx.h"
#include
#include "curl/curl.h"
#include

#include "curl/easy.h"

#include "pthread.h"

using namespace std;

struct tNode
{
FILE *fp;
int startidx;
int maxidx;
void *_curl;
pthread_t _tid;
};
bool bError = false;
int threadCnt = 0;
static pthread_mutex_t foo_mutex = PTHREAD_MUTEX_INITIALIZER;
static size_t downLoadPackage(void *ptr, size_t size, size_t nmemb, void *userdata)
{
tNode *node = (tNode*)userdata;
size_t written = 0;
pthread_mutex_lock(&foo_mutex);
if ( node->startidx + size * nmemb <= node->maxidx )
{
fseek( node->fp, node->startidx, SEEK_SET );
written = fwrite(ptr, size, nmemb, node->fp);
node->startidx += size * nmemb;
}
else
{
fseek( node->fp, node->startidx, SEEK_SET );
written = fwrite(ptr, 1, node->maxidx - node->startidx + 1, node->fp);
node->startidx = node->maxidx;
}
pthread_mutex_unlock(&foo_mutex);
return written;
}

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

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

/************************************************************************/
/* 获取要下载的远程文件的大小 */
/************************************************************************/
long getDownloadFileLenth(const char *url){
double 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;
}

void* workThread(void* pData)
{
tNode* pNode = (tNode*)pData;

int res = curl_easy_perform(pNode->_curl);

if ( res != 0 )
{

}

curl_easy_cleanup(pNode->_curl);

pthread_mutex_lock(&foo_mutex);
threadCnt --;
pthread_mutex_unlock(&foo_mutex);
delete pNode;
pthread_exit(0);

return NULL;
}

bool downLoad(int threadNum, std::string _packageUrl, std::string _storagePath, std::string fileName )
{
long fileLength = getDownloadFileLenth(_packageUrl.c_str());

if ( fileLength <= 0 )
{
printf("get the file error...");
return false;
}

// Create a file to save package.
const string outFileName = _storagePath + fileName;
FILE *fp = fopen(outFileName.c_str(), "wb");
if (! fp)
{
return false;
}

//_chsize((int)fp, fileLength);

int gap = fileLength / threadNum;

for ( int i = 0; i <= threadNum; i ++ )
{
tNode* pNode = new tNode();

if ( i < threadNum )
{
pNode->startidx = i * gap;
pNode->maxidx = pNode->startidx - 1;
}
else
{
if ( fileLength % threadNum != 0 )
{
pNode->startidx = i * gap;
pNode->maxidx = fileLength - 1;
}
}

CURL* _curl = curl_easy_init();

pNode->_curl = _curl;
pNode->fp = fp;