就像标题说我想在C++程序中发送一个带有cUrl库的文件到网络服务器。

我从服务器那里得到了网址和它想要HTTP POST方法和多部分/表单数据的信息。它还需要一个包含数据的参数文件。

我还得到了一个与 curl 控制台一起使用的 cUrl 调用：

curl -X POST -H "Cache-Control： no-cache" -H "Content-Type： multipart/form-data " -F "file=@test.txt" "url"

如果我运行下面的代码，服务器会带来没有上传或没有多部分表单的答案。

现在我的代码：

//## File stuff
struct stat file_info;
FILE *fd;
fopen_s(&fd,"file.txt", "rb"); /* open file to upload */
if (!fd) {
    return 1; /* can't continue */
}
/* to get the file size */
if (fstat(_fileno(fd), &file_info) != 0) {
    return 1; /* can't continue */
}
//##
CURL *hnd = curl_easy_init();
curl_easy_setopt(hnd, CURLOPT_CUSTOMREQUEST, "POST");
curl_easy_setopt(hnd, CURLOPT_URL, "url");
struct curl_slist *headers = NULL;
headers = curl_slist_append(headers, "cache-control: no-cache");
headers = curl_slist_append(headers, "content-type: multipart / form-data");
curl_easy_setopt(hnd, CURLOPT_HTTPHEADER, headers);
curl_easy_setopt(hnd, CURLOPT_UPLOAD, 1L);
curl_easy_setopt(hnd, CURLOPT_READDATA, fd);
curl_easy_setopt(hnd, CURLOPT_INFILESIZE_LARGE,(curl_off_t)file_info.st_size);
CURLcode ret = curl_easy_perform(hnd);

编辑

带有缓冲区文件的新代码：

std::string contents;
std::ifstream in("empty.txt", std::ios::in | std::ios::binary);
if (in)
{
    in.seekg(0, std::ios::end);
    contents.resize(in.tellg());
    in.seekg(0, std::ios::beg);
    in.read(&contents[0], contents.size());
    in.close();
}
CURL *hnd = curl_easy_init();
uint32_t size = contents.size();
//struct curl_slist *headers = NULL;
//headers = curl_slist_append(headers, "cache-control: no-cache");
//headers = curl_slist_append(headers, "content-type: multipart/form-data");
//curl_easy_setopt(hnd, CURLOPT_HTTPHEADER, headers);
curl_easy_setopt(hnd, CURLOPT_URL, "url");
curl_easy_setopt(hnd, CURLOPT_POST, 1);
curl_easy_setopt(hnd, CURLOPT_POSTFIELDS, contents.data());
curl_easy_setopt(hnd, CURLOPT_POSTFIELDSIZE, size);
CURLcode ret = curl_easy_perform(hnd);

现在服务器响应说没有文件数据。我是否也要说它是多部分/表单数据？但是，如果我取消注释标题设置，则响应是有关多形式边界的错误。我也对想要的"file"参数感到困惑。我必须将其添加到CURLOPT_POSTFIELDS吗？

希望你们中的一个人能帮助我谢谢！

编辑最终

知道了。以下代码适用于我与给定服务器设置。

std::string contents;
std::ifstream in("file.txt", std::ios::in | std::ios::binary);
if (in)
{
    in.seekg(0, std::ios::end);
    contents.resize(in.tellg());
    in.seekg(0, std::ios::beg);
    in.read(&contents[0], contents.size());
    in.close();
}
//##

CURL *curl;
CURLcode res;
struct curl_httppost *formpost = NULL;
struct curl_httppost *lastptr = NULL;
struct curl_slist *headerlist = NULL;
static const char buf[] =  "Expect:";
curl_global_init(CURL_GLOBAL_ALL);
// set up the header
curl_formadd(&formpost,
    &lastptr,
    CURLFORM_COPYNAME, "cache-control:",
    CURLFORM_COPYCONTENTS, "no-cache",
    CURLFORM_END);
curl_formadd(&formpost,
    &lastptr,
    CURLFORM_COPYNAME, "content-type:",
    CURLFORM_COPYCONTENTS, "multipart/form-data",
    CURLFORM_END);
curl_formadd(&formpost, &lastptr,
    CURLFORM_COPYNAME, "file",  // <--- the (in this case) wanted file-Tag!
    CURLFORM_BUFFER, "data",
    CURLFORM_BUFFERPTR, contents.data(),
    CURLFORM_BUFFERLENGTH, contents.size(),
    CURLFORM_END);
curl = curl_easy_init();
headerlist = curl_slist_append(headerlist, buf);
if (curl) {
    curl_easy_setopt(curl, CURLOPT_URL, "url");
    curl_easy_setopt(curl, CURLOPT_HTTPPOST, formpost);
    //curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, WriteCallback);
    //curl_easy_setopt(curl, CURLOPT_WRITEDATA, &readBuffer);
    //curl_easy_setopt(curl, CURLOPT_VERBOSE, 1L);
    res = curl_easy_perform(curl);
    /* Check for errors */
    if (res != CURLE_OK)
        fprintf(stderr, "curl_easy_perform() failed: %sn",
            curl_easy_strerror(res));

    curl_easy_cleanup(curl);

    curl_formfree(formpost);
    curl_slist_free_all(headerlist);
}