C++用libcurl通过HTTP以表单的方式Post数据到服务器

一、Post 字符串

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

int main(void)
{
CURL* curl = NULL;
CURLcode res;

curl = curl_easy_init();
if(curl == NULL)
{
return CURLE_FAILED_INIT;
}

struct curl_slist* headerlist = NULL;

// 设置表头，表头内容可能不同
headerlist = curl_slist_append(headerlist, "Content-Type:application/x-www-form-urlencoded");
curl_easy_setopt(curl, CURLOPT_HTTPHEADER, headerlist);

// 设置URL
curl_easy_setopt(curl, CURLOPT_URL, "http://postit.example.com/moo.cgi");

// 设置参数，比如"ParamName1=ParamName1Content&ParamName2=ParamName2Content&..."
curl_easy_setopt(curl, CURLOPT_POSTFIELDS, "name=daniel&project=curl");

// 设置为Post
curl_easy_setopt(curl, CURLOPT_POST, 1);

// 发送
res = curl_easy_perform(curl);

if(res != CURLE_OK)
{
// 获取详细错误信息
char* szErr = curl_easy_strerror(res);
fprintf(stderr, "curl_easy_perform() failed: %s\n", szErr);
}

// 清空
curl_easy_cleanup(curl);

// 释放表头
curl_slist_free_all (headerlist);

return 0;
}

二、Post 文件

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

size_t OnWriteData(void* buffer, size_t size, size_t nmemb, void* lpVoid);

int main(void)
{
CURL* curl = NULL;
CURLcode res;

curl = curl_easy_init();
if(curl == NULL)
{
return CURLE_FAILED_INIT;
}

struct curl_slist* headerlist = NULL;
struct curl_httppost* formpost = NULL;
struct curl_httppost* lastptr = NULL;
std::string strResponse; // 回复

curl_formadd(&formpost, &lastptr,
CURLFORM_COPYNAME, "ParamName1",
CURLFORM_COPYCONTENTS, "ParamName1Content", CURLFORM_END);

curl_formadd(&formpost, &lastptr,
CURLFORM_COPYNAME, "ParamName2",
CURLFORM_COPYCONTENTS, "ParamName2Content", CURLFORM_END);

curl_formadd(&formpost, &lastptr,
CURLFORM_COPYNAME, "ParamName3",
CURLFORM_COPYCONTENTS, "ParamName3Content", CURLFORM_END);

curl_formadd(&formpost, &lastptr,
CURLFORM_COPYNAME, "registerImgs",
CURLFORM_FILE, "C:/Image.png", CURLFORM_END); // 设置要上传的文件

// 设置表单参数
curl_easy_setopt(curl, CURLOPT_HTTPPOST, formpost);

// 设置表头，表头内容可能不同
headerlist = curl_slist_append(headerlist, "Content-Type:application/x-www-form-urlencoded");
curl_easy_setopt(curl, CURLOPT_HTTPHEADER, headerlist);

// 设置URL
curl_easy_setopt(curl, CURLOPT_URL, "http://postit.example.com/moo.cgi");

// 设置参数，比如"ParamName1=ParamName1Content&ParamName2=ParamName2Content&..."
curl_easy_setopt(curl, CURLOPT_POSTFIELDS, "name=daniel&project=curl");

// 设置为Post
curl_easy_setopt(curl, CURLOPT_POST, 1);

curl_easy_setopt(curl, CURLOPT_READFUNCTION, NULL);
curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, OnWriteData);
curl_easy_setopt(curl, CURLOPT_WRITEDATA, (void*)&strResponse);
curl_easy_setopt(curl, CURLOPT_NOSIGNAL, 1);
curl_easy_setopt(curl, CURLOPT_CONNECTTIMEOUT, 3);
curl_easy_setopt(curl, CURLOPT_TIMEOUT, 3);

// 发送
res = curl_easy_perform(curl);

if(res != CURLE_OK)
{
// 获取详细错误信息
char* szErr = curl_easy_strerror(res);
fprintf(stderr, "curl_easy_perform() failed: %s\n", szErr);
}

// 清空
curl_easy_cleanup(curl);

// 释放表单
curl_formfree(formpost);

// 释放表头
curl_slist_free_all (headerlist);

return 0;
}

size_t OnWriteData(void* buffer, size_t size, size_t nmemb, void* lpVoid)
{
std::string* str = dynamic_cast<std::string*>((std::string *)lpVoid);
if( NULL == str || NULL == buffer )
{
return -1;
}

char* pData = (char*)buffer;
str->append(pData, size * nmemb);
return nmemb;
}