使用WinINet和WinHTTP实现HTTP访问

Http访问有两种方式，GET和POST，就编程来说GET方式相对简单点，它不用向服务器提交数据，在这个例程中我使用POST方式，提交数据value1与value2，并从服务器得到他们的和（value1
+ value2）。

为实现Http访问，微软提供了二套API：WinINet, WinHTTP。WinHTTP比WinINet更加安全和健壮，可以这么认为WinHTTP是WinINet的升级版本。这两套API包含了很多相似的函数与宏定义，呵呵，详细对比请查阅msdn中的文章“Porting
WinINet Applications to WinHTTP”，在线MSDN连接：http://msdn2.microsoft.com/en-us/library/aa384068.aspx。

在这个例程中，通过一个宏的设置来决定是使用WinHttp还是WinINet。代码如下:

#define USE_WINHTTP      //Comment this line to user wininet.

下面来说说实现Http访问的流程（两套API都一样的流程）：

1， 首先我们打开一个Session获得一个HINTERNET session句柄；

2， 然后我们使用这个Session句柄与服务器连接得到一个HINTERNET connect句柄；

3， 然后我们使用这个Connect句柄来打开Http
请求得到一个HINTERNET request句柄；

4， 这时我们就可以使用这个Request句柄来发送数据与读取从服务器返回的数据；

5， 最后依次关闭request，connect，session句柄。

在这个例程中以上各个流程都进行了简单封装，以便对比两套API函数的些许差异。下面让源代码说话，原工程是一个windows控制台工程，你可以很容易通过拷贝代码重建工程。

另：如果你从服务器得到的返回数据是utf8格式的文本数据，你将需要对返回的数据进行转换才能正确显示中文，日文等。仅供参考，转换为ATL CStringW的函数见下：

CStringW GetStringWFromUtf8(const std::string& str)
{
int len = MultiByteToWideChar(CP_UTF8, 0, str.c_str(), int(str.length()), 0, 0);

CStringW buf;
WCHAR*    dd = buf.GetBuffer(len);

len = MultiByteToWideChar(CP_UTF8, 0, str.c_str(), int(str.length()), dd, len);

buf.ReleaseBuffer(len);

return buf;
}

完整代码如下：

#include "stdafx.h"
#include <windows.h>
#include <stdio.h>
#include <stdlib.h>

#define _ATL_CSTRING_EXPLICIT_CONSTRUCTORS
#include <atlbase.h>
#include <atlstr.h>

#define USE_WINHTTP    //Comment this line to user wininet.
#ifdef USE_WINHTTP
#include <winhttp.h>
#pragma comment(lib, "winhttp.lib")
#else
#include <wininet.h>
#pragma comment(lib, "wininet.lib")
#endif
#define BUF_SIZE    (1024)

// CrackedUrl
class CrackedUrl {
int m_scheme;
CStringW m_host;
int m_port;
CStringW m_path;
public:
CrackedUrl(LPCWSTR url)
{
URL_COMPONENTS uc = { 0};
uc.dwStructSize = sizeof(uc);

const DWORD BUF_LEN = 256;

WCHAR host[BUF_LEN];
uc.lpszHostName = host;
uc.dwHostNameLength = BUF_LEN;

WCHAR path[BUF_LEN];
uc.lpszUrlPath = path;
uc.dwUrlPathLength = BUF_LEN;

WCHAR extra[BUF_LEN];
uc.lpszExtraInfo = extra;
uc.dwExtraInfoLength = BUF_LEN;

#ifdef USE_WINHTTP
if (!WinHttpCrackUrl(url, 0, ICU_ESCAPE, &uc)) {
printf("Error:WinHttpCrackUrl failed!\n");
}

#else
if (!InternetCrackUrl(url, 0, ICU_ESCAPE, &uc)) {
printf("Error:InternetCrackUrl failed!\n");
}
#endif
m_scheme = uc.nScheme;
m_host = host;
m_port = uc.nPort;
m_path = path;
}

int GetScheme() const
{
return m_scheme;
}

LPCWSTR GetHostName() const
{
return m_host;
}

int GetPort() const
{
return m_port;
}

LPCWSTR GetPath() const
{
return m_path;
}

static CStringA UrlEncode(const char* p)
{
if (p == 0) {
return CStringA();
}

CStringA buf;

for (;;) {
int ch = (BYTE) (*(p++));
if (ch == '\0') {
break;
}

if (isalnum(ch) || ch == '_' || ch == '-' || ch == '.') {
buf += (char)ch;
}
else if (ch == ' ') {
buf += '+';
}
else {
char c[16];
wsprintfA(c, "%%%02X", ch);
buf += c;
}
}

return buf;
}
};

// CrackedUrl
HINTERNET OpenSession(LPCWSTR userAgent = 0)
{
#ifdef USE_WINHTTP
return WinHttpOpen(userAgent, NULL, NULL, NULL, NULL);;
#else
return InternetOpen(userAgent, INTERNET_OPEN_TYPE_PRECONFIG, NULL, NULL, 0);
#endif
}

HINTERNET Connect(HINTERNET hSession, LPCWSTR serverAddr, int portNo)
{
#ifdef USE_WINHTTP
return WinHttpConnect(hSession, serverAddr, (INTERNET_PORT) portNo, 0);
#else
return InternetConnect(hSession, serverAddr, portNo, NULL, NULL, INTERNET_SERVICE_HTTP, 0, 0);
#endif
}

HINTERNET OpenRequest(HINTERNET hConnect, LPCWSTR verb, LPCWSTR objectName, int scheme)
{
DWORD flags = 0;
#ifdef USE_WINHTTP
if (scheme == INTERNET_SCHEME_HTTPS) {
flags |= WINHTTP_FLAG_SECURE;
}

return WinHttpOpenRequest(hConnect, verb, objectName, NULL, NULL, NULL, flags);

#else
if (scheme == INTERNET_SCHEME_HTTPS) {
flags |= INTERNET_FLAG_SECURE;
}

return HttpOpenRequest(hConnect, verb, objectName, NULL, NULL, NULL, flags, 0);
#endif
}

BOOL AddRequestHeaders(HINTERNET hRequest, LPCWSTR header)
{
SIZE_T len = lstrlenW(header);
#ifdef USE_WINHTTP
return WinHttpAddRequestHeaders(hRequest, header, DWORD(len), WINHTTP_ADDREQ_FLAG_ADD);
#else
return HttpAddRequestHeaders(hRequest, header, DWORD(len), HTTP_ADDREQ_FLAG_ADD);
#endif
}

BOOL SendRequest(HINTERNET hRequest, const void* body, DWORD size)
{
#ifdef USE_WINHTTP
return WinHttpSendRequest(hRequest, 0, 0, const_cast<void*>(body), size, size, 0);
#else
return HttpSendRequest(hRequest, 0, 0, const_cast<void*>(body), size);
#endif
}

BOOL EndRequest(HINTERNET hRequest)
{
#ifdef USE_WINHTTP
return WinHttpReceiveResponse(hRequest, 0);
#else
// if you use HttpSendRequestEx to send request then use HttpEndRequest in here!
return TRUE;
#endif
}

BOOL QueryInfo(HINTERNET hRequest, int queryId, char* szBuf, DWORD* pdwSize)
{
#ifdef USE_WINHTTP
return WinHttpQueryHeaders(hRequest, (DWORD) queryId, 0, szBuf, pdwSize, 0);
#else
return HttpQueryInfo(hRequest, queryId, szBuf, pdwSize, 0);
#endif
}

BOOL ReadData(HINTERNET hRequest, void* buffer, DWORD length, DWORD* cbRead)
{
#ifdef USE_WINHTTP
return WinHttpReadData(hRequest, buffer, length, cbRead);
#else
return InternetReadFile(hRequest, buffer, length, cbRead);
#endif
}

void CloseInternetHandle(HINTERNET hInternet)
{
if (hInternet)
{
#ifdef USE_WINHTTP
WinHttpCloseHandle(hInternet);
#else
InternetCloseHandle(hInternet);
#endif
}
}

int _tmain(int argc, _TCHAR* argv[])
{
HINTERNET hSession = 0;
HINTERNET hConnect = 0;
HINTERNET hRequest = 0;
CStringW strHeader(L"Content-type: application/x-www-form-urlencoded\r\n");

// Test data
CrackedUrl crackedUrl(L"http://www.easy-creator.net/test2/add.asp");
CStringA strPostData("value1=10&value2=14");

// Open session.
hSession = OpenSession(L"HttpPost by l_zhaohui@163.com");
if (hSession == NULL) {
printf("Error:Open session!\n");
return -1;
}

// Connect.
hConnect = Connect(hSession, crackedUrl.GetHostName(), crackedUrl.GetPort());
if (hConnect == NULL) {
printf("Error:Connect failed!\n");
return -1;
}

// Open request.
hRequest = OpenRequest(hConnect, L"POST", crackedUrl.GetPath(), crackedUrl.GetScheme());
if (hRequest == NULL) {
printf("Error:OpenRequest failed!\n");
return -1;
}

// Add request header.
if (!AddRequestHeaders(hRequest, strHeader)) {
printf("Error:AddRequestHeaders failed!\n");
return -1;
}

// Send post data.
if (!SendRequest(hRequest, (const char*)strPostData, strPostData.GetLength())) {
printf("Error:SendRequest failed!\n");
return -1;
}

// End request
if (!EndRequest(hRequest)) {
printf("Error:EndRequest failed!\n");
return -1;
}
char szBuf[BUF_SIZE];
DWORD dwSize = 0;
szBuf[0] = 0;

// Query header info.
#ifdef USE_WINHTTP
int contextLengthId = WINHTTP_QUERY_CONTENT_LENGTH;
int statusCodeId = WINHTTP_QUERY_STATUS_CODE;
int statusTextId = WINHTTP_QUERY_STATUS_TEXT;
#else
int contextLengthId = HTTP_QUERY_CONTENT_LENGTH;
int statusCodeId = HTTP_QUERY_STATUS_CODE;
int statusTextId = HTTP_QUERY_STATUS_TEXT;
#endif
dwSize = BUF_SIZE;
if (QueryInfo(hRequest, contextLengthId, szBuf, &dwSize)) {
szBuf[dwSize] = 0;
printf("Content length:[%s]\n", szBuf);
}

dwSize = BUF_SIZE;
if (QueryInfo(hRequest, statusCodeId, szBuf, &dwSize)) {
szBuf[dwSize] = 0;
printf("Status code:[%s]\n", szBuf);
}

dwSize = BUF_SIZE;
if (QueryInfo(hRequest, statusTextId, szBuf, &dwSize)) {
szBuf[dwSize] = 0;
printf("Status text:[%s]\n", szBuf);
}

// read data.
for (;;) {
dwSize = BUF_SIZE;
if (ReadData(hRequest, szBuf, dwSize, &dwSize) == FALSE) {
break;
}

if (dwSize <= 0) {
break;
}

szBuf[dwSize] = 0;
printf("%s\n", szBuf);    //Output value = value1 + value2
}

CloseInternetHandle(hRequest);
CloseInternetHandle(hConnect);
CloseInternetHandle(hSession);

return 0;
}