【C++】纯C++实现http打开网页下载内容的功能

#include "stdafx.h"
#include <windows.h>
#include <iostream>
#include "Wininet.h"
#pragma comment(lib,"Wininet.lib")

using std::cout;
using std::endl;

//模拟浏览器发送HTTP请求函数
std::string HttpRequest(char * lpHostName, short sPort, char * lpUrl, char * lpMethod, char * lpPostData, int nPostDataLen)
{
HINTERNET hInternet, hConnect, hRequest;

BOOL bRet;

std::string strResponse;

hInternet = NULL;
hConnect = NULL;
hRequest = NULL;

hInternet = (HINSTANCE)InternetOpen("User-Agent", INTERNET_OPEN_TYPE_PRECONFIG, NULL, NULL, 0);
if (!hInternet)
goto Ret0;

hConnect = (HINSTANCE)InternetConnect(hInternet, lpHostName, sPort, NULL, "HTTP/1.1", INTERNET_SERVICE_HTTP, 0, 0);
if (!hConnect)
goto Ret0;

hRequest = (HINSTANCE)HttpOpenRequest(hConnect, lpMethod, lpUrl, "HTTP/1.1", NULL, NULL, INTERNET_FLAG_RELOAD, 0);
if (!hRequest)
goto Ret0;

//bRet = HttpAddRequestHeaders(hRequest,"Content-Type: application/x-www-form-urlencoded",Len(FORMHEADERS),HTTP_ADDREQ_FLAG_REPLACE | HTTP_ADDREQ_FLAG_ADD);
//if(!bRet)
//goto Ret0;

bRet = HttpSendRequest(hRequest, NULL, 0, lpPostData, nPostDataLen);
while (TRUE)
{
char cReadBuffer[4096];
unsigned long lNumberOfBytesRead;
bRet = InternetReadFile(hRequest, cReadBuffer, sizeof(cReadBuffer) - 1, &lNumberOfBytesRead);
if (!bRet || !lNumberOfBytesRead)
break;
cReadBuffer[lNumberOfBytesRead] = 0;
strResponse = strResponse + cReadBuffer;
}

Ret0:
if (hRequest)
InternetCloseHandle(hRequest);
if (hConnect)
InternetCloseHandle(hConnect);
if (hInternet)
InternetCloseHandle(hInternet);

return strResponse;
}