这里有一个非常棒的Library用于处理HTTP GET/POST请求： http://www.codeproject.com/KB/library/lyoulhttpclient.aspx

Introduction

This file contains classes which help to interact with a HTTP server. The codes contained in this file depends on the documentation of STLPort 4.6.1 (describing about exception safety).

How to use RyeolHttpClient

In your project, include the following files.

• RyeolException.h
• RyeolException.cpp
• RyeolHttpClient.h
• RyeolHttpClient.cpp
• SafeInt.hpp

In your stdafx.h file, add the following line.

#include "RyeolHttpClient.h"

How to send a request using HTTP GET

CHttpClient supports RequestGet method which sends a request using HTTP GET.

// Retrieves the resource specified by the szUrl using HTTP GET request.
// szUrl            [in] A HTTP URL.
// bUseCache        [in] Specifies whether to use cache.
CHttpResponse * CHttpClient::RequestGet (PCSZ szUrl, BOOL bUseCache = FALSE) throw (Exception &) ;

The following code demonstrates the basic usage of the RequestGet method.

using namespace Ryeol ;

CHttpClient         objHttpReq ;
CHttpResponse *     pobjHttpRes = NULL ;

try {
    // Initialize the User Agent
    objHttpReq.SetInternet (_T ("My User Agent v1.0")) ;

    // Specifies whether to use UTF-8 encoding. (This uses ANSI encoding)
    // Default is FALSE
    objHttpReq.SetUseUtf8 (FALSE) ;

    // Specifies a code page for ANSI strings. (This uses Korean)
    // Default is CP_ACP
    objHttpReq.SetAnsiCodePage (949) ;

    // Add user's custom HTTP headers
    objHttpReq.AddHeader (_T ("Ryeol-Magic"), _T ("My Magic Header")) ;
    objHttpReq.AddHeader (_T ("User-Magic"), _T ("User's Magic Header")) ;

    // Add user's parameters
    objHttpReq.AddParam (_T ("where"), _T ("nexearch")) ;
    objHttpReq.AddParam (_T ("frm"), _T ("t1")) ;
    objHttpReq.AddParam (_T ("query"), _T ("%C3%D6%C1%F6%BF%EC"), CHttpClient::ParamEncodedValue) ;

    // Send a request
    pobjHttpRes = objHttpReq.RequestGet (_T ("http://search.naver.com/search.naver")) ;

    ...     // Place codes to handle the returned CHttpResponse object.

} catch (httpclientexception & e) {
    ...     // Place exception handling codes here.
}

How to send a request using HTTP POST

The HTTP POST method is used in two ways. One is to post simple text, the other is to upload file. To post simple text, CHttpClient provides BeginPost method.

// Starts a new HTTP POST request
// szUrl            [in] A HTTP URL.
// bUseCache        [in] Specifies whether to use cache.
void CHttpClient::BeginPost (PCSZ szUrl, BOOL bUseCache = FALSE) throw (Exception &) ;

The following code demonstrates the basic usage of the BeginPost method.

using namespace Ryeol ;

CHttpClient         objHttpReq ;
CHttpResponse *     pobjHttpRes = NULL ;

try {
    // Initialize the User Agent
    objHttpReq.SetInternet (_T ("My User Agent v1.0")) ;

    // Add user's custom HTTP headers
    objHttpReq.AddHeader (_T ("Ryeol-Magic"), _T ("My Magic Header")) ;
    objHttpReq.AddHeader (_T ("User-Magic"), _T ("User's Magic Header")) ;

    // Add user's parameter
    objHttpReq.AddParam (_T ("st"), _T ("kw")) ;
    objHttpReq.AddParam (_T ("target"), _T ("WinInet")) ;

    // Start a new request
    objHttpReq.BeginPost (_T ("http://www.codeproject.com/info/search.asp")) ;

    // Specifies the number of bytes to send when the Proceed method is called.
    const DWORD     cbProceed = 1024 ;  // 1K

    do {

        ...     // Place codes to report progress information to user.

    } while ( !(pobjHttpRes = objHttpReq.Proceed (cbProceed)) ) ;

    ...     // Place codes to handle the returned CHttpResponse object.

} catch (httpclientexception & e) {
    ...     // Place exception handling codes here.
}

To upload file, CHttpClient provides BeginUpload method.

// Starts a new UPLOAD request
// szUrl            [in] A HTTP URL.
// bUseCache        [in] Specifies whether to use cache.
void CHttpClient::BeginUpload (PCSZ szUrl, BOOL bUseCache = FALSE) throw (Exception &) ;

The following code demonstrates the basic usage of the BeginUpload method.

using namespace Ryeol ;

CHttpClient         objHttpReq ;
CHttpResponse *     pobjHttpRes = NULL ;

try {
    // Initialize the User Agent
    objHttpReq.SetInternet (_T ("My User Agent v1.0")) ;

    // Add user's custom HTTP headers
    objHttpReq.AddHeader (_T ("Ryeol-Magic"), _T ("My Magic Header")) ;
    objHttpReq.AddHeader (_T ("User-Magic"), _T ("User's Magic Header")) ;

    // Add user's parameters
    objHttpReq.AddParam (_T ("nohtml"), _T ("1")) ;
    objHttpReq.AddParam (_T ("title"), _T ("The K-NET photo")) ;
    objHttpReq.AddParam (_T ("content"), _T ("A photo of the K-NET")) ;

    // Specifies a file to upload
    objHttpReq.AddParam (_T ("ufile01"), _T ("D:\\My Photo\\K-NET\\photo1.jpg"), CHttpClient::ParamFile) ;

    // Start a new request
    objHttpReq.BeginUpload (_T ("http://club.hooriza.com/cmd/box.html?clubid=1&boxid=53&action=store&link=")) ;

    // Specifies the number of bytes to send when the Proceed method is called.
    const DWORD     cbProceed = 1024 ;  // 1K

    do {

        ...     // Place codes to report progress information to user.

    } while ( !(pobjHttpRes = objHttpReq.Proceed (cbProceed)) ) ;

    ...     // Place codes to handle the returned CHttpResponse object.

} catch (httpclientexception && e) {
    ...     // Place exception handling codes here.
}

How to handle the returned CHttpResponse object

When you send a request using CHttpClient, all method will return CHttpResponse object. CHttpResponse represents the response returned by a HTTP web server. CHttpResponse provides following methods.

// Returns the number of headers of which name is the szName
DWORD CHttpResponse::GetHeaderCount (PCSZ szName) throw (Exception &) ;

// Returns the header of which name is the szName
PCSZ CHttpResponse::GetHeader (PCSZ szName, DWORD nIdx = 0) throw (Exception &) ;

// Returns the HTTP status code returned by a HTTP server
DWORD CHttpResponse::GetStatus (void) throw (Exception &) ;

// Returns the HTTP status text returned by a HTTP server
PCSZ CHttpResponse::GetStatusText (void) throw (Exception &) ;

// Retrieves the length of the content returned by a HTTP server
BOOL CHttpResponse::GetContentLength (DWORD & cbContLen) throw (Exception &) ;

// Reads the content returned by a HTTP server
DWORD CHttpResponse::ReadContent (BYTE * pbyBuff, DWORD cbBuff) throw (Exception &) ;

The following code demonstrates the basic usage of the CHttpResponse object.

using namespace Ryeol ;

CHttpResponse *     pobjHttpRes = NULL ;

try {
    // Get the CHttpResponse object
    pobjHttpRes = ... ;

    // Reads the HTTP status code
    _tprintf (_T ("%u"), pobjHttpRes->GetStatus ()) ;
    // Reads the HTTP status text
    _tprintf (_T (" %s\n"), pobjHttpRes->GetStatusText ()) ;

    // Reads HTTP headers using an array of header names
    static LPCTSTR      szHeaders[] = 
    { _T ("Server"), _T ("Date"), _T ("X-Powered-By"), _T ("Content-Length"), _T ("Set-Cookie")
    , _T ("Expires"), _T ("Cache-control"), _T ("Connection"), _T ("Transfer-Encoding")
    , _T ("Content-Type") } ;

    LPCTSTR     szHeader ;
    for (size_t i = 0; i < sizeof (szHeaders) / sizeof (LPCTSTR); i++) {
        if ( szHeader = pobjHttpRes->GetHeader (szHeaders[i]) )
            _tprintf (_T ("%s: %s\n"), szHeaders[i], szHeader) ;
        else
            // If the header is not found..
            _tprintf (_T ("'%s' header does not exist..\r\n"), szHeaders[i]) ;
    }

    _tprintf (_T ("\r\n")) ;

    // Checks whether the returned stream is a text
    BOOL        bIsText = FALSE ;
    if ( szHeader = pobjHttpRes->GetHeader (_T ("Content-Type")) )
        bIsText = (0 == ::_tcsncicmp (szHeader, _T ("text/"), 5)) ;

    // Reads the length of the stream
    DWORD       dwContSize ;
    // If the length is not specified
    if ( !pobjHttpRes->GetContentLength (dwContSize) )
        dwContSize = 0 ;

    const DWORD     cbBuff = 1024 * 10 ;
    BYTE            byBuff[cbBuff] ;
    DWORD           dwRead ;
    size_t          cbTotal = 0 ;

    // Reads the data stream returned by the HTTP server.
    while ( dwRead = pobjHttpRes->ReadContent (byBuff, cbBuff - 1) ) {
        cbTotal += dwRead ;

        if ( bIsText ) {
            byBuff[dwRead] = '\0' ;
            printf ("%s", reinterpret_cast<LPCSTR> (byBuff)) ;
        }
    }

    if ( !bIsText )
        _tprintf (_T ("%u bytes skipped..\n"), cbTotal) ;

} catch (httpclientexception & e) {
    ...     // Place exception handling codes here.
}

delete pobjHttpRes ;
pobjHttpRes = NULL ;

How to handle exception

When an error occurred, httpclientexception object is thrown.

class httpclientexception {
public:
    // Returns the last error code. The error codes is defined in RyeolHttpClient.h
    DWORD LastError (void) const throw () ;

    // Returns the last error message.
    LPCTSTR errmsg (void) const throw () ;

    // Returns the last win32 error code retrieved by using ::GetLastError when an error occurred.
    DWORD Win32LastError (void) const throw () ;
} ;

Before throwing an exception, most methods restore their internal states. (all or nothing like transaction) But if you call BeginPost or BeginUpload method, the POST context is automatically canceled. You should write the following try-catch block to handle the exception.

using namespace Ryeol ;

try {

    ...     // Place codes which throw a httpclientexception exception

} catch (httpclientexception & e) {
    _tprintf (_T ("An error has been occured\n")) ;
    _tprintf (_T ("ErrCode: 0x%x\n"), e.LastError ()) ;
    _tprintf (_T ("ErrMsg: %s\n"), e.errmsg ()) ;
    if ( e.Win32LastError () != NO_ERROR ) {
        TCHAR       szErrMsg[512] ;
        GetWinInetErrMsg (szErrMsg, 512, e.Win32LastError ()) ;

        _tprintf (_T ("Win32ErrCode: 0x%x\n"), e.Win32LastError ()) ;
        _tprintf (_T ("Win32ErrMsg: %s\n"), szErrMsg) ;
    }
}

How to show progress information to user

If you call BeginPost or BeginUpload method, you can retrieve progress information using Query method.

// Queries progress information of the current POST context
// objPostStat      [out] A CHttpPostStat object.
void CHttpClient::Query (CHttpPostStat & objPostStat) throw () ;

CHttpPostStat represents progress information of the current POST context. The following code demonstrates the basic usage of the CHttpPostStat object.

using namespace Ryeol ;

CHttpClient         objHttpReq ;
CHttpResponse *     pobjHttpRes = NULL ;
size_t              cbProceed = 1024 ;  // 1k

try {
    ... ;   // Intialize the CHttpClient object

    // Starts a new POST request
    objHttpReq.BeginPost (...) or objHttpReq.BeginUpload (...) ;

    // Displays progress information
    CHttpPostStat       objPostStat ;

    do {
        // Retrieves progress information
        objHttpReq.Query (objPostStat) ;

        _tprintf (_T ("\nPost in progress... %2u/%2u\n")
            , objPostStat.PostedCount ()            // The number of posted parameters
            , objPostStat.TotalCount ()) ;          // The total number of parameters

        _tprintf (_T ("%s: %10u/%10u %10u/%10u %10u/%10u\n")
            , objPostStat.CurrParam ()              // The name of the current parameter
            , objPostStat.CurrParamPostedByte ()    // The number of posted bytes of the current parameter
            , objPostStat.CurrParamTotalByte ()     // The total number of bytes of the current parameter
            , objPostStat.PostedByte ()             // The number of posted bytes of the request
            , objPostStat.TotalByte ()              // The total number of bytes of the request
            , objPostStat.ActualPostedByte ()       // The actual number of posted bytes of the request
            , objPostStat.ActualTotalByte ()) ;     // The actual total number of bytes of the request

        // If the current parameter is a file parameter, displays the file path
        if ( objPostStat.CurrParamIsFile () )
            _tprintf (_T ("-->%s\n")
                , objPostStat.CurrFile ()) ;

        // Sends the number of bytes specified by cbProceed to the server
    } while ( !(pobjHttpRes = objHttpReq.Proceed (cbProceed)) ) ;

    ... ;   // Handles the returned CHttpResponse object

} catch (httpclientexception & e) {
    ...     // Place exception handling codes here.
}