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：
1// HttpPost.cpp written by [email protected] 2// 2007/11/30 3#include "stdafx.h" 4#include 5#include 6#include 7 8#define _ATL_CSTRING_EXPLICIT_CONSTRUCTORS 9#include 10#include 11 12#define USE_WINHTTP //Comment this line to user wininet. 13#ifdef USE_WINHTTP 14 #include 15 #pragma comment(lib, "winhttp.lib") 16#else 17 #include 18 #pragma comment(lib, "wininet.lib") 19#endif 20#define BUF_SIZE (1024) 21 22// CrackedUrl 23class CrackedUrl { 24 int m_scheme; 25 CStringW m_host; 26 int m_port; 27 CStringW m_path; 28public: 29 CrackedUrl(LPCWSTR url) 30 { 31 URL_COMPONENTS uc = { 0}; 32 uc.dwStructSize = sizeof(uc); 33 34 const DWORD BUF_LEN = 256; 35 36 WCHAR host[BUF_LEN]; 37 uc.lpszHostName = host; 38 uc.dwHostNameLength = BUF_LEN; 39 40 WCHAR path[BUF_LEN]; 41 uc.lpszUrlPath = path; 42 uc.dwUrlPathLength = BUF_LEN; 43 44 WCHAR extra[BUF_LEN]; 45 uc.lpszExtraInfo = extra; 46 uc.dwExtraInfoLength = BUF_LEN; 47 48#ifdef USE_WINHTTP 49 if (!WinHttpCrackUrl(url, 0, ICU_ESCAPE, &uc)) { 50 printf("Error:WinHttpCrackUrl failed!/n"); 51 } 52 53#else 54 if (!InternetCrackUrl(url, 0, ICU_ESCAPE, &uc)) { 55 printf("Error:InternetCrackUrl failed!/n"); 56 } 57#endif 58 m_scheme = uc.nScheme; 59 m_host = host; 60 m_port = uc.nPort; 61 m_path = path; 62 } 63 64 int GetScheme() const 65 { 66 return m_scheme; 67 } 68 69 LPCWSTR GetHostName() const 70 { 71 return m_host; 72 } 73 74 int GetPort() const 75 { 76 return m_port; 77 } 78 79 LPCWSTR GetPath() const 80 { 81 return m_path; 82 } 83 84 static CStringA UrlEncode(const char* p) 85 { 86 if (p == 0) { 87 return CStringA(); 88 } 89 90 CStringA buf; 91 92 for (;;) { 93 int ch = (BYTE) (*(p++)); 94 if (ch == '/0') { 95 break; 96 } 97 98 if (isalnum(ch) || ch == '_' || ch == '-' || ch == '.') { 99 buf += (char)ch; 100 } 101 else if (ch == ' ') { 102 buf += '+'; 103 } 104 else { 105 char c[16]; 106 wsprintfA(c, "%%%02X", ch); 107 buf += c; 108 } 109 } 110 111 return buf; 112 } 113}; 114 115// CrackedUrl 116HINTERNET OpenSession(LPCWSTR userAgent = 0) 117{ 118#ifdef USE_WINHTTP 119 return WinHttpOpen(userAgent, NULL, NULL, NULL, NULL);; 120#else 121 return InternetOpen(userAgent, INTERNET_OPEN_TYPE_PRECONFIG, NULL, NULL, 0); 122#endif 123} 124 125HINTERNET Connect(HINTERNET hSession, LPCWSTR serverAddr, int portNo) 126{ 127#ifdef USE_WINHTTP 128 return WinHttpConnect(hSession, serverAddr, (INTERNET_PORT) portNo, 0); 129#else 130 return InternetConnect(hSession, serverAddr, portNo, NULL, NULL, INTERNET_SERVICE_HTTP, 0, 0); 131#endif 132} 133 134HINTERNET OpenRequest(HINTERNET hConnect, LPCWSTR verb, LPCWSTR objectName, int scheme) 135{ 136 DWORD flags = 0; 137#ifdef USE_WINHTTP 138 if (scheme == INTERNET_SCHEME_HTTPS) { 139 flags |= WINHTTP_FLAG_SECURE; 140 } 141 142 return WinHttpOpenRequest(hConnect, verb, objectName, NULL, NULL, NULL, flags); 143 144#else 145 if (scheme == INTERNET_SCHEME_HTTPS) { 146 flags |= INTERNET_FLAG_SECURE; 147 } 148 149 return HttpOpenRequest(hConnect, verb, objectName, NULL, NULL, NULL, flags, 0); 150#endif 151} 152 153BOOL AddRequestHeaders(HINTERNET hRequest, LPCWSTR header) 154{ 155 SIZE_T len = lstrlenW(header); 156#ifdef USE_WINHTTP 157 return WinHttpAddRequestHeaders(hRequest, header, DWORD(len), WINHTTP_ADDREQ_FLAG_ADD); 158#else 159 return HttpAddRequestHeaders(hRequest, header, DWORD(len), HTTP_ADDREQ_FLAG_ADD); 160#endif 161} 162 163BOOL SendRequest(HINTERNET hRequest, const void* body, DWORD size) 164{ 165#ifdef USE_WINHTTP 166 return WinHttpSendRequest(hRequest, 0, 0, const_cast(body), size, size, 0); 167#else 168 return HttpSendRequest(hRequest, 0, 0, const_cast(body), size); 169#endif 170} 171 172BOOL EndRequest(HINTERNET hRequest) 173{ 174#ifdef USE_WINHTTP 175 return WinHttpReceiveResponse(hRequest, 0); 176#else 177 // if you use HttpSendRequestEx to send request then use HttpEndRequest in here! 178 return TRUE; 179#endif 180} 181 182BOOL QueryInfo(HINTERNET hRequest, int queryId, char* szBuf, DWORD* pdwSize) 183{ 184#ifdef USE_WINHTTP 185 return WinHttpQueryHeaders(hRequest, (DWORD) queryId, 0, szBuf, pdwSize, 0); 186#else 187 return HttpQueryInfo(hRequest, queryId, szBuf, pdwSize, 0); 188#endif 189} 190 191BOOL ReadData(HINTERNET hRequest, void* buffer, DWORD length, DWORD* cbRead) 192{ 193#ifdef USE_WINHTTP 194 return WinHttpReadData(hRequest, buffer, length, cbRead); 195#else 196 return InternetReadFile(hRequest, buffer, length, cbRead); 197#endif 198} 199 200void CloseInternetHandle(HINTERNET hInternet) 201{ 202 if (hInternet) 203 { 204#ifdef USE_WINHTTP 205 WinHttpCloseHandle(hInternet); 206#else 207 InternetCloseHandle(hInternet); 208#endif 209 } 210} 211 212int _tmain(int argc, _TCHAR* argv[]) 213{ 214 HINTERNET hSession = 0; 215 HINTERNET hConnect = 0; 216 HINTERNET hRequest = 0; 217 CStringW strHeader(L"Content-type: application/x-www-form-urlencoded/r/n"); 218 219 // Test data 220 CrackedUrl crackedUrl(L"http://www.easy-creator.net/test2/add.asp"); 221 CStringA strPostData("value1=10&value2=14"); 222 223 // Open session. 224 hSession = OpenSession(L"HttpPost by [email protected]"); 225 if (hSession == NULL) { 226 printf("Error:Open session!/n"); 227 return -1; 228 } 229 230 // Connect. 231 hConnect = Connect(hSession, crackedUrl.GetHostName(), crackedUrl.GetPort()); 232 if (hConnect == NULL) { 233 printf("Error:Connect failed!/n"); 234 return -1; 235 } 236 237 // Open request. 238 hRequest = OpenRequest(hConnect, L"POST", crackedUrl.GetPath(), crackedUrl.GetScheme()); 239 if (hRequest == NULL) { 240 printf("Error:OpenRequest failed!/n"); 241 return -1; 242 } 243 244 // Add request header. 245 if (!AddRequestHeaders(hRequest, strHeader)) { 246 printf("Error:AddRequestHeaders failed!/n"); 247 return -1; 248 } 249 250 // Send post data. 251 if (!SendRequest(hRequest, (const char*)strPostData, strPostData.GetLength())) { 252 printf("Error:SendRequest failed!/n"); 253 return -1; 254 } 255 256 // End request 257 if (!EndRequest(hRequest)) { 258 printf("Error:EndRequest failed!/n"); 259 return -1; 260 } 261 262 char szBuf[BUF_SIZE]; 263 DWORD dwSize = 0; 264 szBuf[0] = 0; 265 266 // Query header info. 267#ifdef USE_WINHTTP 268 int contextLengthId = WINHTTP_QUERY_CONTENT_LENGTH; 269 int statusCodeId = WINHTTP_QUERY_STATUS_CODE; 270 int statusTextId = WINHTTP_QUERY_STATUS_TEXT; 271#else 272 int contextLengthId = HTTP_QUERY_CONTENT_LENGTH; 273 int statusCodeId = HTTP_QUERY_STATUS_CODE; 274 int statusTextId = HTTP_QUERY_STATUS_TEXT; 275#endif 276 dwSize = BUF_SIZE; 277 if (QueryInfo(hRequest, contextLengthId, szBuf, &dwSize)) { 278 szBuf[dwSize] = 0; 279 printf("Content length:[%s]/n", szBuf); 280 } 281 282 dwSize = BUF_SIZE; 283 if (QueryInfo(hRequest, statusCodeId, szBuf, &dwSize)) { 284 szBuf[dwSize] = 0; 285 printf("Status code:[%s]/n", szBuf); 286 } 287 288 dwSize = BUF_SIZE; 289 if (QueryInfo(hRequest, statusTextId, szBuf, &dwSize)) { 290 szBuf[dwSize] = 0; 291 printf("Status text:[%s]/n", szBuf); 292 } 293 294 // read data. 295 for (;;) { 296 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 307 } 308 309 CloseInternetHandle(hRequest); 310 CloseInternetHandle(hConnect); 311 CloseInternetHandle(hSession); 312 313 return 0; 314}
