[MFC]建立典型HTTP Client应用程序的步骤

The following table shows the steps you might perform in a typical HTTP client application:

Your goal	Actions you take	Effects
Begin an HTTP session.	Create a CInternetSession object.	Initializes WinInet and connects to server.
Connect to an HTTP server.	Use CInternetSession::GetHttpConnection.	Returns a CHttpConnection object.
Open an HTTP request.	Use CHttpConnection::OpenRequest.	Returns a CHttpFile object.
Send an HTTP request.	Use CHttpFile::AddRequestHeaders and CHttpFile::SendRequest.	Finds the file. Returns FALSE if the file is not found.
Read from the file.	Use CHttpFile.	Reads the specified number of bytes using a buffer you supply.
Handle exceptions.	Use the CInternetException class.	Handles all common Internet exception types.
End the HTTP session.	Dispose of the CInternetSession object.	Automatically cleans up open file handles and connections.