C++使用libcurl做HttpClient

    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 

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 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 *)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);	}

	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;}