当使用C++做HTTP客户端时，目前通用的做法就是使用libcurl。其官方网站的地址是http://curl.haxx.se/，该网站主要提供了Curl和libcurl。Curl是命令行工具，用于完成FTP, FTPS, HTTP, HTTPS, GOPHER, TELNET, DICT, FILE 以及 LDAP的命令的请求及接收回馈。libcurl提供给开发者，用于使用C++跨平台的开发各种网络协议的请求及响应。里面的文档非常齐全，不过都是英文的。
本文提供最简单的demo使用libcurl开发HttpClient。主要包括同步的HTTP GET、HTTP POST、HTTPS GET、HTTPS POST。
下载libcurl包，如果使用Linux平台，建议下载源文件编译；如果使用Windows平台，建议下载Win32 - MSVC，下载地址是：http://curl.haxx.se/download.html
#ifndef __HTTP_CURL_H__
#define __HTTP_CURL_H__
#include <string>
class CHttpClient
{
public:
CHttpClient(void);
~CHttpClient(void);
public:
/**
* @brief HTTP POST请求
* @param strUrl 输入参数,请求的Url地址,如:http://www.baidu.com
* @param strPost 输入参数,使用如下格式para1=val1¶2=val2&…
* @param strResponse 输出参数,返回的内容
* @return 返回是否Post成功
*/
int Post(const std::string & strUrl, const std::string & strPost, std::string & strResponse);
/**
* @brief HTTP GET请求
* @param strUrl 输入参数,请求的Url地址,如:http://www.baidu.com
* @param strResponse 输出参数,返回的内容
* @return 返回是否Post成功
*/
int Get(const std::string & strUrl, std::string & strResponse);
/**
* @brief HTTPS POST请求,无证书版本
* @param strUrl 输入参数,请求的Url地址,如:https://www.alipay.com
* @param strPost 输入参数,使用如下格式para1=val1¶2=val2&…
* @param strResponse 输出参数,返回的内容
* @param pCaPath 输入参数,为CA证书的路径.如果输入为NULL,则不验证服务器端证书的有效性.
* @return 返回是否Post成功
*/
int Posts(const std::string & strUrl, const std::string & strPost, std::string & strResponse, const char * pCaPath = NULL);
/**
* @brief HTTPS GET请求,无证书版本
* @param strUrl 输入参数,请求的Url地址,如:https://www.alipay.com
* @param strResponse 输出参数,返回的内容
* @param pCaPath 输入参数,为CA证书的路径.如果输入为NULL,则不验证服务器端证书的有效性.
* @return 返回是否Post成功
*/
int Gets(const std::string & strUrl, std::string & strResponse, const char * pCaPath = NULL);
public:
void SetDebug(bool bDebug);
private:
bool m_bDebug;
};
#endif
#include "httpclient.h"
#include "curl/curl.h"
#include <string>
CHttpClient::CHttpClient(void) :
m_bDebug(false)
{
}
CHttpClient::~CHttpClient(void)
{
}
static int OnDebug(CURL *, curl_infotype itype, char * pData, size_t size, void *)
{
if(itype == CURLINFO_TEXT)
{
//printf("[TEXT]%s\n", pData);
}
else if(itype == CURLINFO_HEADER_IN)
{
printf("[HEADER_IN]%s\n", pData);
}
else if(itype == CURLINFO_HEADER_OUT)
{
printf("[HEADER_OUT]%s\n", pData);
}
else if(itype == CURLINFO_DATA_IN)
{
printf("[DATA_IN]%s\n", pData);
}
else if(itype == CURLINFO_DATA_OUT)
{
printf("[DATA_OUT]%s\n", pData);
}
return 0;
}
static 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;
}
int CHttpClient::Post(const std::string & strUrl, const std::string & strPost, std::string & strResponse)
{
CURLcode res;
CURL* curl = curl_easy_init();
if(NULL == curl)
{
return CURLE_FAILED_INIT;
}
if(m_bDebug)
{
curl_easy_setopt(curl, CURLOPT_VERBOSE, 1);
curl_easy_setopt(curl, CURLOPT_DEBUGFUNCTION, OnDebug);
}
curl_easy_setopt(curl, CURLOPT_URL, strUrl.c_str());
curl_easy_setopt(curl, CURLOPT_POST, 1);
curl_easy_setopt(curl, CURLOPT_POSTFIELDS, strPost.c_str());
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);
res = curl_easy_perform(curl);
curl_easy_cleanup(curl);
return res;
}
int CHttpClient::Get(const std::string & strUrl, std::string & strResponse)
{
CURLcode res;
CURL* curl = curl_easy_init();
if(NULL == curl)
{
return CURLE_FAILED_INIT;
}
if(m_bDebug)
{
curl_easy_setopt(curl, CURLOPT_VERBOSE, 1);
curl_easy_setopt(curl, CURLOPT_DEBUGFUNCTION, OnDebug);
}
<pre name="code" class="cpp"> curl_easy_setopt(curl, CURLOPT_URL, strUrl.c_str());
curl_easy_setopt(curl, CURLOPT_READFUNCTION, NULL);
curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, OnWriteData);
curl_easy_setopt(curl, CURLOPT_WRITEDATA, (void *)&strResponse);
/**
* 当多个线程都使用超时处理的时候，同时主线程中有sleep或是wait等操作。
* 如果不设置这个选项，libcurl将会发信号打断这个wait从而导致程序退出。
*/
curl_easy_setopt(curl, CURLOPT_NOSIGNAL, 1);
curl_easy_setopt(curl, CURLOPT_CONNECTTIMEOUT, 3);
curl_easy_setopt(curl, CURLOPT_TIMEOUT, 3);
res = curl_easy_perform(curl);
curl_easy_cleanup(curl);
return res;
}
int CHttpClient::Posts(const std::string & strUrl, const std::string & strPost, std::string & strResponse, const char * pCaPath)
{
CURLcode res;
CURL* curl = curl_easy_init();
if(NULL == curl)
{
return CURLE_FAILED_INIT;
}
if(m_bDebug)
{
curl_easy_setopt(curl, CURLOPT_VERBOSE, 1);
curl_easy_setopt(curl, CURLOPT_DEBUGFUNCTION, OnDebug);
}
curl_easy_setopt(curl, CURLOPT_URL, strUrl.c_str());
curl_easy_setopt(curl, CURLOPT_POST, 1);
curl_easy_setopt(curl, CURLOPT_POSTFIELDS, strPost.c_str());
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);
if(NULL == pCaPath)
{
curl_easy_setopt(curl, CURLOPT_SSL_VERIFYPEER, false);
curl_easy_setopt(curl, CURLOPT_SSL_VERIFYHOST, false);
}
else
{
//缺省情况就是PEM，所以无需设置，另外支持DER
//curl_easy_setopt(curl,CURLOPT_SSLCERTTYPE,"PEM");
curl_easy_setopt(curl, CURLOPT_SSL_VERIFYPEER, true);
curl_easy_setopt(curl, CURLOPT_CAINFO, pCaPath);
}
curl_easy_setopt(curl, CURLOPT_CONNECTTIMEOUT, 3);
curl_easy_setopt(curl, CURLOPT_TIMEOUT, 3);
res = curl_easy_perform(curl);
curl_easy_cleanup(curl);
return res;
}
int CHttpClient::Gets(const std::string & strUrl, std::string & strResponse, const char * pCaPath)
{
CURLcode res;
CURL* curl = curl_easy_init();
if(NULL == curl)
{
return CURLE_FAILED_INIT;
}
if(m_bDebug)
{
curl_easy_setopt(curl, CURLOPT_VERBOSE, 1);
curl_easy_setopt(curl, CURLOPT_DEBUGFUNCTION, OnDebug);
}
curl_easy_setopt(curl, CURLOPT_URL, strUrl.c_str());
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);
if(NULL == pCaPath)
{
curl_easy_setopt(curl, CURLOPT_SSL_VERIFYPEER, false);
curl_easy_setopt(curl, CURLOPT_SSL_VERIFYHOST, false);
}
else
{
curl_easy_setopt(curl, CURLOPT_SSL_VERIFYPEER, true);
curl_easy_setopt(curl, CURLOPT_CAINFO, pCaPath);
}
curl_easy_setopt(curl, CURLOPT_CONNECTTIMEOUT, 3);
curl_easy_setopt(curl, CURLOPT_TIMEOUT, 3);
res = curl_easy_perform(curl);
curl_easy_cleanup(curl);
return res;
}
///
void CHttpClient::SetDebug(bool bDebug)
{
m_bDebug = bDebug;
}
参考：
https://www.yuque.com/docs/share/c0731a51-7f19-44e6-a312-70f815bd8f0e
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