从 Dropbox 在 C++ 中通过 curl 下载文件

Question

我想在 C++ 程序中使用 curl 从共享的保管箱下载文件 link

我找到了一个 dropbox api pdf 告诉我如何做

#include <stdio.h>
#include <curl/curl.h>

int main (int argc, char *argv[])
{
     CURL *curl;
     CURLcode res;
     /* In windows, this will init the winsock stuff */
     curl_global_init(CURL_GLOBAL_ALL);
     /* get a curl handle */
     curl = curl_easy_init();
     if(curl) {
     printf ("Running curl test.\n");
     struct curl_slist *headers=NULL; /* init to NULL is important */
     headers = curl_slist_append(headers, "Authorization: Bearer 
     <ACCESS_TOKEN>");
     headers = curl_slist_append(headers, "Content-Type:");
     headers = curl_slist_append(headers, "Dropbox-API-Arg: 
     {\"path\":\"/test.txt\"}");
     curl_easy_setopt(curl, CURLOPT_HTTPHEADER, headers);
    curl_easy_setopt(curl, CURLOPT_URL,
    "https://content.dropboxapi.com/2/files/download");
     curl_easy_setopt(curl, CURLOPT_POSTFIELDS, "");
     /* Perform the request, res will get the return code */
     res = curl_easy_perform(curl);
     /* Check for errors */
     if(res != CURLE_OK)
        fprintf(stderr, "curl_easy_perform() failed: %s\n",

     curl_easy_strerror(res));
    /* always cleanup */
    curl_easy_cleanup(curl);
    printf ("\nFinished curl test.\n");
    }
          curl_global_cleanup();
         printf ("Done!\n");
           return 0;
         }

然而，所提供的评论并没有为我提供太多解释，我无法让它发挥作用。

这三行代码我看不懂：

headers = curl_slist_append(headers, "Authorization: Bearer <ACCESS_TOKEN>");

headers = curl_slist_append(headers, "Content-Type:");

headers = curl_slist_append(headers, "Dropbox-API-Arg:{\"path\":\"/test.txt\"}");

我想我必须更换一些东西，但我不知道是什么

Answer 1

"I think I have to replace some stuff but I don't know what" : 将 <ACCESS_TOKEN> 替换为您的实际访问令牌。

您还应该将 "Content-Type:" header 设置为适合您正在获取的数据的值。

您还必须更改 "Dropbox-API-Arg" header 的值以匹配您尝试获取的文件。

Answer 2

我终于找到了解决问题的方法。

原来我不必使用 Dropbox API

这是代码

#include <iostream>
#include <curl/curl.h>

using namespace std;

size_t write_data(void *ptr, size_t size, size_t nmemb, FILE *stream)
{
  size_t written;
  written = fwrite(ptr, size, nmemb, stream);
  return written;
}

int main(int argc, char** argv) {

CURL *curl;
FILE *fp;

const char* destination = "D:\Desktop\test.exe";

fp = fopen(destination, "wb");

curl = curl_easy_init();

/* A long parameter set to 1 tells the library to follow any Location: header 
 * that the server sends as part of an HTTP header in a 3xx response. The 
 *Location: header can specify a relative or an absolute URL to follow.
*/
curl_easy_setopt(curl, CURLOPT_FOLLOWLOCATION, 1L); 

curl_easy_setopt(curl, CURLOPT_URL, "https://www.dropbox.com/s/09nd26tdyto23yz/BankAccount.exe?dl=1"); // "dl=0"changed to "dl=1" to force download

// disabe the SSL peer certificate verification allowing the program to download the file from dropbox shared link
// in case it is not used it displays an error message stating "SSL peer certificate or SSH remote key was not OK"
curl_easy_setopt(curl, CURLOPT_SSL_VERIFYPEER, FALSE);

curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, write_data);

curl_easy_setopt(curl, CURLOPT_WRITEDATA, fp);

CURLcode res;

res = curl_easy_perform(curl);

curl_easy_cleanup(curl);

fclose(fp);


if (res ==CURLE_OK)
    cout << "OK";
else
    cout << curl_easy_strerror(res);

return 0;
}

感谢你们试图帮助我。我很感激

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