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：

// HttpPost.cpp written by l_zhaohui@163.com
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// 2007/11/30
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#include " stdafx.h "
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#include < windows.h >
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#include < stdio.h >
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#include < stdlib.h >
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#define _ATL_CSTRING_EXPLICIT_CONSTRUCTORS
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#include < atlbase.h >
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#include < atlstr.h >
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#define USE_WINHTTP // Comment this line to user wininet.
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#ifdef USE_WINHTTP
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#include < winhttp.h >
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#pragma comment(lib, " winhttp.lib " )
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# else
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#include < wininet.h >
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#pragma comment(lib, " wininet.lib " )
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#endif
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#define BUF_SIZE ( 1024 )
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// CrackedUrl
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class CrackedUrl {
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int m_scheme;
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CStringW m_host;
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int m_port;
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CStringW m_path;
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public:
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CrackedUrl(LPCWSTR url)
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{
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URL_COMPONENTS uc = { 0};
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uc.dwStructSize = sizeof(uc);
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const DWORD BUF_LEN = 256;
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WCHAR host[BUF_LEN];
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uc.lpszHostName = host;
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uc.dwHostNameLength = BUF_LEN;
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WCHAR path[BUF_LEN];
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uc.lpszUrlPath = path;
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uc.dwUrlPathLength = BUF_LEN;
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WCHAR extra[BUF_LEN];
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uc.lpszExtraInfo = extra;
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uc.dwExtraInfoLength = BUF_LEN;
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#ifdef USE_WINHTTP
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if (!WinHttpCrackUrl(url, 0, ICU_ESCAPE, &uc)) {
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printf("Error:WinHttpCrackUrl failed!\n");
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}
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#else
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if (!InternetCrackUrl(url, 0, ICU_ESCAPE, &uc)) {
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printf("Error:InternetCrackUrl failed!\n");
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}
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#endif
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m_scheme = uc.nScheme;
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m_host = host;
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m_port = uc.nPort;
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m_path = path;
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}
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int GetScheme() const
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{
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return m_scheme;
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}
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LPCWSTR GetHostName() const
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{
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return m_host;
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}
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int GetPort() const
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{
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return m_port;
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}
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LPCWSTR GetPath() const
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{
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return m_path;
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}
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static CStringA UrlEncode(const char* p)
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{
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if (p == 0) {
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return CStringA();
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}
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CStringA buf;
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for (;;) {
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int ch = (BYTE) (*(p++));
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if (ch == '\0') {
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break;
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}
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if (isalnum(ch) || ch == '_' || ch == '-' || ch == '.') {
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buf += (char)ch;
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}
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else if (ch == ' ') {
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buf += '+';
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}
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else {
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char c[16];
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wsprintfA(c, "%%%02X", ch);
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buf += c;
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}
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}
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return buf;
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}
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} ;
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// CrackedUrl
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HINTERNET OpenSession(LPCWSTR userAgent = 0 )
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{
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#ifdef USE_WINHTTP
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return WinHttpOpen(userAgent, NULL, NULL, NULL, NULL);;
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#else
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return InternetOpen(userAgent, INTERNET_OPEN_TYPE_PRECONFIG, NULL, NULL, 0);
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#endif
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}
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HINTERNET Connect(HINTERNET hSession, LPCWSTR serverAddr, int portNo)
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{
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#ifdef USE_WINHTTP
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return WinHttpConnect(hSession, serverAddr, (INTERNET_PORT) portNo, 0);
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#else
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return InternetConnect(hSession, serverAddr, portNo, NULL, NULL, INTERNET_SERVICE_HTTP, 0, 0);
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#endif
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}
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HINTERNET OpenRequest(HINTERNET hConnect, LPCWSTR verb, LPCWSTR objectName, int scheme)
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{
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DWORD flags = 0;
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#ifdef USE_WINHTTP
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if (scheme == INTERNET_SCHEME_HTTPS) {
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flags |= WINHTTP_FLAG_SECURE;
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}
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return WinHttpOpenRequest(hConnect, verb, objectName, NULL, NULL, NULL, flags);
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#else
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if (scheme == INTERNET_SCHEME_HTTPS) {
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flags |= INTERNET_FLAG_SECURE;
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}
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return HttpOpenRequest(hConnect, verb, objectName, NULL, NULL, NULL, flags, 0);
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#endif
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}
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BOOL AddRequestHeaders(HINTERNET hRequest, LPCWSTR header)
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{
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SIZE_T len = lstrlenW(header);
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#ifdef USE_WINHTTP
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return WinHttpAddRequestHeaders(hRequest, header, DWORD(len), WINHTTP_ADDREQ_FLAG_ADD);
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#else
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return HttpAddRequestHeaders(hRequest, header, DWORD(len), HTTP_ADDREQ_FLAG_ADD);
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#endif
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}
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BOOL SendRequest(HINTERNET hRequest, const void * body, DWORD size)
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{
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#ifdef USE_WINHTTP
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return WinHttpSendRequest(hRequest, 0, 0, const_cast<void*>(body), size, size, 0);
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#else
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return HttpSendRequest(hRequest, 0, 0, const_cast<void*>(body), size);
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#endif
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}
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BOOL EndRequest(HINTERNET hRequest)
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{
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#ifdef USE_WINHTTP
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return WinHttpReceiveResponse(hRequest, 0);
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#else
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// if you use HttpSendRequestEx to send request then use HttpEndRequest in here!
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return TRUE;
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#endif
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}
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BOOL QueryInfo(HINTERNET hRequest, int queryId, char * szBuf, DWORD * pdwSize)
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{
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#ifdef USE_WINHTTP
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return WinHttpQueryHeaders(hRequest, (DWORD) queryId, 0, szBuf, pdwSize, 0);
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#else
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return HttpQueryInfo(hRequest, queryId, szBuf, pdwSize, 0);
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#endif
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}
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BOOL ReadData(HINTERNET hRequest, void * buffer, DWORD length, DWORD * cbRead)
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{
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#ifdef USE_WINHTTP
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return WinHttpReadData(hRequest, buffer, length, cbRead);
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#else
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return InternetReadFile(hRequest, buffer, length, cbRead);
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#endif
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}
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void CloseInternetHandle(HINTERNET hInternet)
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{
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if (hInternet)
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{
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#ifdef USE_WINHTTP
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WinHttpCloseHandle(hInternet);
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#else
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InternetCloseHandle(hInternet);
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#endif
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}
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}
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int _tmain( int argc, _TCHAR * argv[])
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{
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HINTERNET hSession = 0;
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HINTERNET hConnect = 0;
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HINTERNET hRequest = 0;
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CStringW strHeader(L"Content-type: application/x-www-form-urlencoded\r\n");
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// Test data
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CrackedUrl crackedUrl(L"http://www.easy-creator.net/test2/add.asp");
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CStringA strPostData("value1=10&value2=14");
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// Open session.
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hSession = OpenSession(L"HttpPost by l_zhaohui@163.com");
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if (hSession == NULL) {
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printf("Error:Open session!\n");
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return -1;
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}
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// Connect.
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hConnect = Connect(hSession, crackedUrl.GetHostName(), crackedUrl.GetPort());
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if (hConnect == NULL) {
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printf("Error:Connect failed!\n");
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return -1;
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}
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// Open request.
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hRequest = OpenRequest(hConnect, L"POST", crackedUrl.GetPath(), crackedUrl.GetScheme());
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if (hRequest == NULL) {
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printf("Error:OpenRequest failed!\n");
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return -1;
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}
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// Add request header.
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if (!AddRequestHeaders(hRequest, strHeader)) {
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printf("Error:AddRequestHeaders failed!\n");
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return -1;
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}
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// Send post data.
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if (!SendRequest(hRequest, (const char*)strPostData, strPostData.GetLength())) {
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printf("Error:SendRequest failed!\n");
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return -1;
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}
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// End request
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if (!EndRequest(hRequest)) {
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printf("Error:EndRequest failed!\n");
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return -1;
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}
261

262

char szBuf[BUF_SIZE];
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DWORD dwSize = 0;
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szBuf[0] = 0;
265

266

// Query header info.
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#ifdef USE_WINHTTP
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int contextLengthId = WINHTTP_QUERY_CONTENT_LENGTH;
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int statusCodeId = WINHTTP_QUERY_STATUS_CODE;
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int statusTextId = WINHTTP_QUERY_STATUS_TEXT;
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#else
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int contextLengthId = HTTP_QUERY_CONTENT_LENGTH;
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int statusCodeId = HTTP_QUERY_STATUS_CODE;
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int statusTextId = HTTP_QUERY_STATUS_TEXT;
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#endif
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dwSize = BUF_SIZE;
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if (QueryInfo(hRequest, contextLengthId, szBuf, &dwSize)) {
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szBuf[dwSize] = 0;
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printf("Content length:[%s]\n", szBuf);
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}
281

282

dwSize = BUF_SIZE;
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if (QueryInfo(hRequest, statusCodeId, szBuf, &dwSize)) {
284

szBuf[dwSize] = 0;
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printf("Status code:[%s]\n", szBuf);
286

}
287

288

dwSize = BUF_SIZE;
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if (QueryInfo(hRequest, statusTextId, szBuf, &dwSize)) {
290

szBuf[dwSize] = 0;
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printf("Status text:[%s]\n", szBuf);
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}
293

294

// read data.
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for (;;) {
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dwSize = BUF_SIZE;
297

if (ReadData(hRequest, szBuf, dwSize, &dwSize) == FALSE) {
298

break;
299

}
300

301

if (dwSize <= 0) {
302

break;
303

}
304

305

szBuf[dwSize] = 0;
306

printf("%s\n", szBuf); //Output value = value1 + value2
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}
308

309

CloseInternetHandle(hRequest);
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CloseInternetHandle(hConnect);
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CloseInternetHandle(hSession);
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313

return 0;
314

}
315

=========================================================================================

wininet　api函数使用经验点滴

一.使用HttpSendRequestEx后，如需使用HttpQueryInfo，需先用HttpEndRequest结束Request

二.BOOL HttpQueryInfo(
    IN HINTERNET hHttpRequest,
    IN DWORD dwInfoLevel,
    IN LPVOID lpvBuffer,
    IN LPDWORD lpdwBufferLength,
    IN OUT LPDWORD lpdwIndex,
);
lpdwBufferLength会返回所需的Buffer大小，因此如果多次使用此函数，需要多次对lpdwBufferLength赋值，否则会出现ERROR_INSUFFICIENT_BUFFER错误
示例程序：

hHttpFile=HttpOpenRequest(hConnect,"POST","/avlab/index.php",NULL,NULL,0,INTERNET_FLAG_DONT_CACHE|INTERNET_FLAG_NO_COOKIES|INTERNET_FLAG_KEEP_CONNECTION|INTERNET_FLAG_RELOAD,0);HttpAddRequestHeaders(hHttpFile,szCookie,-1,HTTP_ADDREQ_FLAG_ADD);HttpAddRequestHeaders(hHttpFile,"Content-Type: application/x-www-form-urlencoded",-1,HTTP_ADDREQ_FLAG_ADD);HttpSendRequestEx(hHttpFile,&struInterIn,NULL,NULL,NULL);HttpEndRequest(hHttpFile,NULL,NULL,NULL);nLength=512;//这一句很重要，，因为HttpQueryInfo返回的时候，会改变此值HttpQueryInfo(hHttpFile,HTTP_QUERY_SET_COOKIE,szBuffer,(unsigned long *)&nLength,NULL);

三.使用InternetReadFile一定要记得比较已经读取的字节数,以确定数据是否已经全部读完
如果InternetReadFile未把response的数据读完,后续的request会被response数据淹没,而得不到服务端的及时响应或者无响应.这时候再HttpSendRequest,后续的HttpQueryInfo会不成功

四.字符串操作时,一定要检查返回值,以防后续代码进行非法操作

五.
如果向网页提交带参数的get或者post命令，网站需要处理时间，其返回网址的内容可能还没有更新过，如果需要获取更新后的内容，需要对更新前后的内容进行比较

六.
　HttpSendRequest或者HttpSendRequestEx发送消息后如果未接受到response，则会返回NULL,Error Code被设为12002,即超时错误，可以使用 InternetSetOption(hHttpFile,INTERNET_OPTION_SEND_TIMEOUT,&timeout,sizeof(DWORD)); 设置超时时间

七.
不能太依赖服务器提供的文件大小,因为有的时候服务器并不提供文件大小,此时如果再使用HttpQueryInfo获取大小,则会出错,GetLastError()返回值为12150