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CHttpConnection Class

  • Artikkel

Manages your connection to an HTTP server.

Syntax

class CHttpConnection : public CInternetConnection

Members

Public Constructors

Name Description
CHttpConnection::CHttpConnection Creates a CHttpConnection object.

Public Methods

Name Description
CHttpConnection::OpenRequest Opens an HTTP request.

Remarks

HTTP is one of three Internet server protocols implemented by the MFC WinInet classes.

The class CHttpConnection contains a constructor and one member function, OpenRequest, that manages connections to a server with an HTTP protocol.

To communicate with an HTTP server, you must first create an instance of CInternetSession, and then create a CHttpConnection object. You never create a CHttpConnection object directly; rather, call CInternetSession::GetHttpConnection, which creates the CHttpConnection object and returns a pointer to it.

To learn more about how CHttpConnection works with the other MFC Internet classes, see the article Internet Programming with WinInet. For more information about connecting to servers using the other two supported Internet protocols, gopher and FTP, see the classes CGopherConnection and CFtpConnection.

Inheritance Hierarchy

CObject

CInternetConnection

CHttpConnection

Requirements

Header: afxinet.h

CHttpConnection::CHttpConnection

This member function is called to construct a CHttpConnection object.

CHttpConnection(
    CInternetSession* pSession,
    HINTERNET hConnected,
    LPCTSTR pstrServer,
    DWORD_PTR dwContext);

CHttpConnection(
    CInternetSession* pSession,
    LPCTSTR pstrServer,
    INTERNET_PORT nPort = INTERNET_INVALID_PORT_NUMBER,
    LPCTSTR pstrUserName = NULL,
    LPCTSTR pstrPassword = NULL,
    DWORD_PTR dwContext = 1);

CHttpConnection(
    CInternetSession* pSession,
    LPCTSTR pstrServer,
    DWORD dwFlags,
    INTERNET_PORT nPort = INTERNET_INVALID_PORT_NUMBER,
    LPCTSTR pstrUserName = NULL,
    LPCTSTR pstrPassword = NULL,
    DWORD_PTR dwContext = 1);

Parameters

pSession
A pointer to a CInternetSession object.

hConnected
A handle to an Internet connection.

pstrServer
A pointer to a string containing the server name.

dwContext
The context identifier for the CInternetConnection object. For more information about dwContext, see the Remarks section.

nPort
The number that identifies the Internet port for this connection.

pstrUserName
Pointer to a null-terminated string that specifies the name of the user to sign in. If NULL, the default is anonymous.

pstrPassword
A pointer to a null-terminated string that specifies the password to use to sign in. If both pstrPassword and pstrUserName are NULL, the default anonymous password is the user's email name. If pstrPassword is NULL or an empty string, but pstrUserName is not NULL, a blank password is used. The following table describes the behavior for the four possible settings of pstrUserName and pstrPassword:

pstrUserName pstrPassword Username sent to FTP server Password sent to FTP server
NULL or " " NULL or " " "anonymous" User's email name
Non-NULL String NULL or " " pstrUserName " "
NULL Non-NULL String ERROR ERROR
Non-NULL String Non-NULL String pstrUserName pstrPassword

dwFlags
Any combination of the INTERNET_FLAG_* flags. See the table in the Remarks section of CHttpConnection::OpenRequest for a description of dwFlags values.

Remarks

You never create a CHttpConnection directly. Rather, you create an object by calling CInternetSession::GetHttpConnection.

CHttpConnection::OpenRequest

Call this member function to open an HTTP connection.

CHttpFile* OpenRequest(
    LPCTSTR pstrVerb,
    LPCTSTR pstrObjectName,
    LPCTSTR pstrReferer = NULL,
    DWORD_PTR dwContext = 1,
    LPCTSTR* ppstrAcceptTypes = NULL,
    LPCTSTR pstrVersion = NULL,
    DWORD dwFlags = INTERNET_FLAG_EXISTING_CONNECT);

CHttpFile* OpenRequest(
    int nVerb,
    LPCTSTR pstrObjectName,
    LPCTSTR pstrReferer = NULL,
    DWORD_PTR dwContext = 1,
    LPCTSTR* ppstrAcceptTypes = NULL,
    LPCTSTR pstrVersion = NULL,
    DWORD dwFlags = INTERNET_FLAG_EXISTING_CONNECT);

Parameters

pstrVerb
A pointer to a string containing the verb to use in the request. If NULL, "GET" is used.

pstrObjectName
A pointer to a string containing the target object of the specified verb. This string is generally a filename, an executable module, or a search specifier.

pstrReferer
A pointer to a string that specifies the address (URL) of the document from which the URL in the request (pstrObjectName) was obtained. If NULL, no HTTP header is specified.

dwContext
The context identifier for the OpenRequest operation. For more information about dwContext, see the Remarks section.

ppstrAcceptTypes
A pointer to a null-terminated array of LPCTSTR pointers to strings indicating content types accepted by the client. If ppstrAcceptTypes is NULL, the servers interpret that the client only accepts documents of type "text/*" (that is, only text documents and not pictures or other binary files). The content type is equivalent to the CGI variable CONTENT_TYPE, which identifies the type of data for queries that have attached information, such as HTTP POST and PUT.

pstrVersion
A pointer to a string defining the HTTP version. If NULL, "HTTP/1.0" is used.

dwFlags
Any combination of the INTERNET_ FLAG_* flags. See the Remarks section for a description of possible dwFlags values.

nVerb
A number associated with the HTTP request type. Can be one of the following:

HTTP request type nVerb value
HTTP_VERB_POST 0
HTTP_VERB_GET 1
HTTP_VERB_HEAD 2
HTTP_VERB_PUT 3
HTTP_VERB_LINK 4
HTTP_VERB_DELETE 5
HTTP_VERB_UNLINK 6

Return Value

A pointer to the CHttpFile object requested.

Remarks

dwFlags can be one of the following:

Internet flag Description
INTERNET_FLAG_RELOAD Forces a download of the requested file, object, or directory listing from the origin server, not from the cache.
INTERNET_FLAG_DONT_CACHE Doesn't add the returned entity to the cache.
INTERNET_FLAG_MAKE_PERSISTENT Adds the returned entity to the cache as a persistent entity. It means that standard cache cleanup, consistency checking, or garbage collection cannot remove this item from the cache.
INTERNET_FLAG_SECURE Uses secure transaction semantics. It translates to using SSL/PCT and is only meaningful in HTTP requests
INTERNET_FLAG_NO_AUTO_REDIRECT Used only with HTTP, specifies that redirections shouldn't be handled automatically in CHttpFile::SendRequest.

Override the dwContext default to set the context identifier to a value of your choosing. The context identifier is associated with this specific operation of the CHttpConnection object created by its CInternetSession object. The value is returned to CInternetSession::OnStatusCallback to provide status on the operation with which it's identified. See the article Internet First Steps: WinInet for more information about the context identifier.

Exceptions may be thrown with this function.

See also

CInternetConnection Class
Hierarchy Chart
CInternetConnection Class
CHttpFile Class