curl 达成下载文件特定片段

发布时间：2021-11-20 13:02:32 所属栏目：PHP教程来源：互联网

导读：通过设置CURLOPT_RANGE可以下载服务器端文件的特定数据块，这样如果服务器数据很大的情况下，如果只是需其中一小块数据就可以采用这种方法当然这个也可以用来多线程加速下载同一个文件 #include stdafx.h #include curl/curl.h #include string/*注意包含这

通过设置CURLOPT_RANGE可以下载服务器端文件的特定数据块，这样如果服务器数据很大的情况下，如果只是需其中一小块数据就可以采用这种方法

当然这个也可以用来多线程加速下载同一个文件

#include "stdafx.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;

struct RecordNode
{
public:
int idx;
int data[10000];
void SetData(int i)
{
  idx = i;
  for ( int j = 0; j < 10000; j ++ )
  {
   data[j] = i + j;
  }
}
};

struct BufferNode
{
char ptrBuff[40004];
int cur;
int max;
};

BufferNode node;

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;
BufferNode* pBuf = /*&node;*/(BufferNode*)userdata;
size_t cnt = size * nmemb;
if ( pBuf->cur + nmemb <= pBuf->max )
{
  memcpy(&(pBuf->ptrBuff[pBuf->cur]), ptr, cnt);
  pBuf->cur += cnt;
}
else
{
  //printf("over flow...n");
  memcpy(&(pBuf->ptrBuff[pBuf->cur]), ptr, pBuf->max - pBuf->cur);
  pBuf->cur += pBuf->max - pBuf->cur;

}

return nmemb;
}

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;
}

bool downLoad(void *_curl, std::string _packageUrl, int idx )
{
// Create a file to save package.
//BufferNode node;
node.cur = 0;
node.max = sizeof(RecordNode);
//node.ptrBuff = new char[node.max];
char szRange[128] ={};
size_t nodeSize = sizeof(RecordNode);
sprintf( szRange, "%d-%d", idx * nodeSize, (idx + 1)*nodeSize );

// 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, &node);
curl_easy_setopt(_curl, CURLOPT_NOPROGRESS, false);
curl_easy_setopt(_curl, CURLOPT_PROGRESSFUNCTION, assetsManagerProgressFunc);
//curl_easy_setopt(_curl, CURLOPT_PROGRESSDATA, this);
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_TIMEOUT, 20);        //设置超时
curl_easy_setopt(_curl, CURLOPT_NOSIGNAL, 1);        //屏蔽其它信号
curl_easy_setopt(_curl, CURLOPT_HEADER, 0);          //下载数据包括HTTP头部
curl_easy_setopt(_curl, CURLOPT_RANGE, /*"0-500"*/szRange);    //用于断点续传, 设置下载的分片

res = curl_easy_perform(_curl);
curl_easy_cleanup(_curl);
if (res != 0)
{
  printf("error: failed to download datan");
  return false;
}

if(node.cur == node.max)
{
  RecordNode record;
  memcpy(&record, node.ptrBuff, sizeof(RecordNode));
  printf(".....idx:%d,data3:%d.......n", record.idx, record.data[2]);
}
else
{
  printf("error: data not correctn");
}

//delete[] node.ptrBuff;

return true;
}

void GenerateData()
{
FILE *fp = fopen("records.dat", "wb");
if (!fp)
{
  return;
}

for ( int i = 0; i < 10000; i ++ )
{
  RecordNode node;
  node.SetData(i);
  size_t written = fwrite(&node, sizeof(RecordNode), 1, fp);
}

fclose(fp);

fp = fopen("records.dat", "rb");
if (!fp)
{
  return;
}
RecordNode nodeBuf;
fread(&nodeBuf, sizeof(RecordNode), 1, fp);
printf("idx:%d,data3:%dn", nodeBuf.idx, nodeBuf.data[2]);
fseek(fp,-1 * int(sizeof(RecordNode)), SEEK_END);
fread(&nodeBuf,sizeof(RecordNode), 1, fp);
printf("idx:%d,data3:%dn", nodeBuf.idx, nodeBuf.data[2]);
fclose(fp);
}

int _tmain(int argc, _TCHAR* argv[])
{
//GenerateData();

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/records.dat", 1);
_curl = curl_easy_init();
downLoad(_curl, "http://localhost/records.dat", 10);
_curl = curl_easy_init();
downLoad(_curl, "http://localhost/records.dat", 28);
getchar();
return 0;
}

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