MFC 通过 http (post/get) 访问WEB（接口）服务器，并取得服务器返回数据

关键系统函数

CHttpConnection* CInternetSession::GetHttpConnection
CHttpFile* CHttpConnection::OpenRequest
CHttpFile::SendRequest
CInternetFile::Read

访问接口函数

//strMethod:类型包含 POST/GET ,strUrl访问的网址,strPostData:类型为POST时提交给服务器的数据,strResponse:服务器返回数据
int CHttpData::ExecuteRequest(LPCTSTR strMethod, LPCTSTR strUrl, CString/*LPCTSTR*/ strPostData, CString &strResponse)  
{  
    CString strServer;  
    CString strObject;  
    DWORD dwServiceType;  
    INTERNET_PORT nPort;  
    strResponse = _T("");  

	CInternetSession sess;//Create session  
    AfxParseURL(strUrl, dwServiceType, strServer, strObject, nPort);  //解析url
  
    //判断协议类型是否为http或https
    if(AFX_INET_SERVICE_HTTP != dwServiceType && AFX_INET_SERVICE_HTTPS != dwServiceType)  
    {  
		LoggerCio::notice(LoggerCio::LOG_URL,"*** url 非http或https 协议！");//log输出
		return FAILURE;
    }    
    try  
    {  	//CHttpConnection *m_pConnection;//定义在头文件
	    //获取 CHttpConnection*
        m_pConnection = sess.GetHttpConnection(strServer,dwServiceType == AFX_INET_SERVICE_HTTP ? NORMAL_CONNECT : SECURE_CONNECT,nPort);  
        //获取 CHttpFile*
        m_pFile = m_pConnection->OpenRequest(strMethod, strObject,NULL, 1, NULL, NULL,(dwServiceType == AFX_INET_SERVICE_HTTP ? NORMAL_REQUEST : SECURE_REQUEST));  

		m_pFile -> AddRequestHeaders( _T("Accept:application/json;"));
		m_pFile -> AddRequestHeaders( _T("Content-Type:application/json;charset=utf-8;"));
		m_pFile -> AddRequestHeaders( _T("Content-Type:multipart/form-data;"));		

		USES_CONVERSION;
		char *pData = T2A(strPostData);
		if (NULL == m_pFile){
			LOG_FUNC_QUIT_DEBUG(LOG_SYS);
			return FAILURE;  
		}
		//发送请求
		if(m_pFile->SendRequest(NULL, 0,pData,strlen(pData)))
		{
			char szChars[BUFFER_SIZE + 1] = {0};
			string strRawResponse = "";
			UINT nReaded = 0;  
			while ((nReaded = m_pFile->Read((void*)szChars, BUFFER_SIZE)) > 0)
			{//接收返回
				szChars[nReaded] = '\0';
				strRawResponse += szChars;
				memset(szChars, 0, BUFFER_SIZE + 1);
			}

			//将多字符转宽字节存为 CString
			int unicodeLen = MultiByteToWideChar(CP_UTF8, 0, strRawResponse.c_str(), -1, NULL, 0);
			WCHAR *pUnicode = new WCHAR[unicodeLen + 1];  
			memset(pUnicode,0,(unicodeLen+1)*sizeof(wchar_t));    
			MultiByteToWideChar(CP_UTF8,0,strRawResponse.c_str(),-1, pUnicode,unicodeLen);  
			CString cs(pUnicode);
			delete []pUnicode;
			pUnicode = NULL;

			strResponse = cs;
		}
		else{//请求失败打印错误码
			DWORD dwError = GetLastError();  
			LoggerCio::notice(LoggerCio::LOG_URL,"*** m_pFile->SendRequest 失败，GetLastError=%d",dwError);
		}
  
        Clear();
    }  
    catch (CInternetException* e)  
    {  //捕获CInternetException异常
        Clear();  
        DWORD dwErrorCode = e->m_dwError;  
        e->Delete();  
		e = NULL;
  
        DWORD dwError = GetLastError();  

		LoggerCio::notice(LoggerCio::LOG_URL,"*** CHttpData 网络异常，错误代码[CInternetException::m_dwError:%d][GetLastError:%d] ***",dwErrorCode,dwError);
  
        if (ERROR_INTERNET_TIMEOUT == dwErrorCode)  
            return OUTTIME; //超时
        else  
            return FAILURE;  //错误
    }  
    return SUCCESS;  //成功
}  

调用示例

		//我的post数据一般格式，Json库是 JsonCpp
		//格式化json串
		Json::Value root;
		root["id"] = Json::Value(theApp.g_nID);
		root["verify"] = Json::Value(CSTR_2_STR(theApp.g_strVerify));
		root["check_time"] = Json::Value(theApp.g_nCheckTime);
		root["oem"] = Json::Value("");
		strPostData= STR_2_CSTR(root.toStyledString());
		
		ExecuteRequest(_T("POST"), strUrl/*请求接口*/, strPostData/*接口所需的参数，这个需要和接口提供方协商，一般是json字串*/, strResponse/*服务器返回的字串*/);