C/C++使用libcurl库发送http请求

拼搏现实的明天。 2022-01-20 01:53 349阅读 0赞

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

#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