C++要实现http网络连接，需要借助第三方库，libcurl使用起来还是很方便的

环境：win32 + vs2015

如果要在linux下使用，用cmake编译，使用基本同理

1，下载编译libcurl

下载curl源码，找到vs工程，按照x86 x64 并对应debug和release编译出静态库lib

2，构建工程

1）curl头文件和lib拷贝到工程目录

2）配置附加包含目录libcurl中的include和附加库目录libcurl中的lib目录

3）添加预编译宏USE_OPENSSL和CURL_STATICLIB

4）添加附加依赖库

ws2_32.lib
wldap32.lib
crypt32.lib
advapi32.lib
libcurl.lib

注意版本对应

3，代码示例

#include <iostream>
#include <string>
#include "curl/curl.h"
using namespace std;

#pragma comment(lib, "ws2_32.lib")
#pragma comment(lib, "wldap32.lib")
#pragma comment(lib, "crypt32.lib")
#pragma comment(lib, "advapi32.lib")
#pragma comment(lib, "libcurl.lib")

// reply of the requery
size_t req_reply(void *ptr, size_t size, size_t nmemb, void *stream)
{
	cout << "----->reply" << endl;
	string *str = (string*)stream;
	cout << *str << endl;
	(*str).append((char*)ptr, size*nmemb);
	return size * nmemb;
}

// http GET
CURLcode curl_get_req(const std::string &url, std::string &response)
{
	// init curl
	CURL *curl = curl_easy_init();
	// res code
	CURLcode res;
	if (curl)
	{
		// set params
		curl_easy_setopt(curl, CURLOPT_URL, url.c_str()); // url
		curl_easy_setopt(curl, CURLOPT_SSL_VERIFYPEER, false); // if want to use https
		curl_easy_setopt(curl, CURLOPT_SSL_VERIFYHOST, false); // set peer and host verify false
		curl_easy_setopt(curl, CURLOPT_VERBOSE, 1);
		curl_easy_setopt(curl, CURLOPT_READFUNCTION, NULL);
		curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, req_reply);
		curl_easy_setopt(curl, CURLOPT_WRITEDATA, (void *)&response);
		curl_easy_setopt(curl, CURLOPT_NOSIGNAL, 1);
		curl_easy_setopt(curl, CURLOPT_HEADER, 1);
		curl_easy_setopt(curl, CURLOPT_CONNECTTIMEOUT, 3); // set transport and time out time
		curl_easy_setopt(curl, CURLOPT_TIMEOUT, 3);
		// start req
		res = curl_easy_perform(curl);
	}
	// release curl
	curl_easy_cleanup(curl);
	return res;
}

// http POST
CURLcode curl_post_req(const string &url, const string &postParams, string &response)
{
	// init curl
	CURL *curl = curl_easy_init();
	// res code
	CURLcode res;
	if (curl)
	{
		// set params
		curl_easy_setopt(curl, CURLOPT_POST, 1); // post req
		curl_easy_setopt(curl, CURLOPT_URL, url.c_str()); // url
		curl_easy_setopt(curl, CURLOPT_POSTFIELDS, postParams.c_str()); // params
		curl_easy_setopt(curl, CURLOPT_SSL_VERIFYPEER, false); // if want to use https
		curl_easy_setopt(curl, CURLOPT_SSL_VERIFYHOST, false); // set peer and host verify false
		curl_easy_setopt(curl, CURLOPT_VERBOSE, 1);
		curl_easy_setopt(curl, CURLOPT_READFUNCTION, NULL);
		curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, req_reply);
		curl_easy_setopt(curl, CURLOPT_WRITEDATA, (void *)&response);
		curl_easy_setopt(curl, CURLOPT_NOSIGNAL, 1);
		curl_easy_setopt(curl, CURLOPT_HEADER, 1);
		curl_easy_setopt(curl, CURLOPT_CONNECTTIMEOUT, 3);
		curl_easy_setopt(curl, CURLOPT_TIMEOUT, 3);
		// start req
		res = curl_easy_perform(curl);
	}
	// release curl
	curl_easy_cleanup(curl);
	return res;
}

int main()
{
	// global init
	curl_global_init(CURL_GLOBAL_ALL);

	// test get requery
	string getUrlStr = "http://cn.bing.com/images/trending?form=Z9LH";
	string getResponseStr;
	auto res = curl_get_req(getUrlStr, getResponseStr);
	if (res != CURLE_OK)
		cerr << "curl_easy_perform() failed: " + string(curl_easy_strerror(res)) << endl;
	else
		cout << getResponseStr << endl;

	// test post requery
	string postUrlStr = "https://www.baidu.com/s";
	string postParams = "f=8&rsv_bp=1&rsv_idx=1&word=picture&tn=98633779_hao_pg";
	string postResponseStr;
	auto res = curl_post_req(postUrlStr, postParams, postResponseStr);
	if (res != CURLE_OK)
		cerr << "curl_easy_perform() failed: " + string(curl_easy_strerror(res)) << endl;
	else
		cout << postResponseStr << endl;

	// global release
	curl_global_cleanup();
	system("pause");
	return 0;
}

• get和post可以用于请求html信息，也可以请求xml和json等串
• 可以添加自定义的header 域和cookies
• 这是libcurl的简单接口，基本等同于阻塞试请求，libcurl有高阶的异步并发接口，运用更复杂