使用libcurl POST数据和上传文件

  • 为了具有通用性,将文件的内容读到了fc变量中,fclen是fc的长度。fc也可以是任何其它内容。curl 是 libcurl句柄。演示省略了很多显而易见的步骤。
     
    1. 普通的post请求,这里用curl_easy_escape对fc做了编码
    std::string data("req=plain");
    data.append("&file=");
    char *efc = curl_easy_escape(curl, fc, fclen);
    data.append(efc)
    curl_free(encoded);
     
    curl_easy_setopt(curl, CURLOPT_URL, PURGE_URL);
    curl_easy_setopt(curl, CURLOPT_POST, 1L);
    curl_easy_setopt(curl, CURLOPT_POSTFIELDS, data.c_str());
    curl_easy_setopt(curl, CURLOPT_POSTFIELDSIZE, data.size());
     
    2. multipart/formdata请求
    struct curl_httppost *formpost = 0;
    struct curl_httppost *lastptr  = 0;
    curl_formadd(&formpost, &lastptr, CURLFORM_PTRNAME, "reqformat", CURLFORM_PTRCONTENTS, "plain", CURLFORM_END);
    curl_formadd(&formpost, &lastptr, CURLFORM_PTRNAME, "file", CURLFORM_PTRCONTENTS, fc, CURLFORM_CONTENTSLENGTH, fclen, CURLFORM_END);
     
    curl_easy_setopt(curl, CURLOPT_URL, URL);
    curl_easy_setopt(curl, CURLOPT_HTTPPOST, formpost);
    curl_easy_perform(curl);
    curl_formfree(formpost);
     
    3. multipart/formdata请求,不把文件读入fc,其它步骤相同
    curl_formadd(&formpost, &lastptr, CURLFORM_PTRNAME, "file", CURLFORM_FILE, "/path/filename", CURLFORM_END);
     
    4. 通过put上传文件
    curl_easy_setopt(curl, CURLOPT_UPLOAD, 1L);
    curl_easy_setopt(curl, CURLOPT_PUT, 1L);
    curl_easy_setopt(curl, CURLOPT_READDATA, fp);   // FILE *fp = fopen("/path/filename");
    curl_easy_setopt(curl, CURLOPT_INFILESIZE_LARGE, fsize);  // fsize = sizeof /path/filename
     
    5. 发送自己的Header
    struct curl_slist *slist = 0;
    slist = curl_slist_append(slist, "Blog-X-User: username");
    slist = curl_slist_append(slist, "Blog-X-Signature: signature");
    curl_easy_setopt(curl, CURLOPT_HTTPHEADER, slist);
    curl_slist_free_all(slist);

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