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delphi自学的好教材！特别适合刚刚起步学习delphi的人员！同样对使用者具有参考价值！

	<DT></DT>
	<DD><B>1. </B>Choose Component | Import ActiveX Control from the main menu. The Import
	ActiveX dialog box is displayed.
	<P>
	<DT></DT>
	<DD><B>2. </B>Locate Microsoft Internet Controls (Version 1.<I>x</I>) in the list
	of ActiveX controls (see Figure BD.4). If you have Internet Explorer 3 installed,
	the version number will be 1.0. If you have Internet Explorer 4 installed, the control
	will be listed as version 1.1. Notice that the Class names field shows TWebBrowser
	as the control contained in this file. If you have Internet Explorer 4, the Class
	names field will also show TWebBrowser_V1 (the original WebBrowser control) and TShellFolderViewOC.
	<P>
</DL>

<P><A HREF="javascript:popUp('28672204.gif')"><B>FIGURE BD.4.</B></A><B> </B><I>The
Import ActiveX dialog box.</I></P>

<DL>
	<DT><I></I></DT>
	<P>
	<DT><I></I></DT>
	<DD><B>3. </B>Click Install to install the control (the rest of the fields on this
	dialog box can be left on their default values).
	<P>
	<DT></DT>
	<DD><B>4. </B>The Install dialog box appears asking for a package name. Click on
	the Into new package tab at the top of the dialog and type IE in the File name field.
	(You can type a description if you want, but it's not necessary.) Click OK to create
	the package.
	<P>
	<DT></DT>
	<DD><B>5. </B>A confirmation dialog box appears asking whether you want to build
	and install the package. Click Yes to create the package.
	<P>
</DL>

<P>Delphi builds the package and then displays a dialog box saying that the TWebBrowser
control has been installed. Now you can try out the control:</P>

<DL>
	<DT></DT>
	<DD><B>1. </B>First, choose File | Close All to close all windows, and then create
	a new application.
	<P>
	<DT></DT>
	<DD><B>2. </B>Click the ActiveX tab on the Component palette. Choose the WebBrowser
	control and drop it on your main form. Size the control as desired, but leave room
	on the form for a button.
	<P>
	<DT></DT>
	<DD><B>3. </B>Drop a Button component on the form. Double-click the button to generate
	an OnClick event handler. Type the following code in the event handler (use any URL
	you want):
	<P>
</DL>



<BLOCKQUOTE>
	<PRE>WebBrowser1.Navigate(`http:\\www.turbopower.com', 
  EmptyParam, EmptyParam, EmptyParam, EmptyParam););</PRE>

</BLOCKQUOTE>

<PRE></PRE>

<DL>
	<DT></DT>
	<DD>As you might surmise, the Navigate method loads the document in the Web browser.
	<P>
	<DT></DT>
	<DD><B>4. </B>Click the Run button to run the program.
	<P>
</DL>

<P>When the program runs, click the form's button. The Web page will load and be
displayed in the WebBrowser control.</P>
<P>When you install this control, Delphi creates a unit called SHDocVw_TLB.pas. You
can look at this unit to see what properties and methods are available for TWebBrowser.</P>


<BLOCKQUOTE>
	<P>
<HR>
<strong>TIP:</strong> You can find documentation for the WebBrowser control on Microsoft's
	Web site. Search the Microsoft site for the text Reusing the WebBrowser Control.
	
<HR>


</BLOCKQUOTE>

<P>Notice that you can't redistribute the TWebBrowser control itself without obtaining
a license from Microsoft. However, if you know your users have Internet Explorer
installed on their systems, your application will work because the control is already
installed. You still have to register the control on your user's machine for your
application to run. See &quot;Deploying Internet Applications&quot; later in this
chapter for more information on registering ActiveX controls.</P>
<P>
<H2><A NAME="Heading8"></A>Sending Mail</H2>
<P>There are many reasons you might want to send mail from one of your applications.
The good news is that sending email isn't difficult at all. Maybe you want your program
users to be able to email you with any problems they encounter. In that case, your
application could pop up a form containing a Memo component and a Send button. Your
users can type text in the Memo component, press the Send button, and the message
is emailed to you. You can even go so far as to attach a log file from your application
to diagnose any problems the user is having.</P>
<P>The TNMSMTP control is used for sending mail through an SMTP server. SMTP is an
odd protocol in that it doesn't require authenticated logon to the server (at least
on most SMTP servers). You can simply connect to any mail server, send the email
message, and disconnect. The Host property is used to specify the host name of the
mail server to which you want to connect. Most of the time, you can just use mail
as the host name. Specifying mail tells the TNMSMTP control to connect to your local
mail server, whether it's your ISP's mail server or your company's mail server.</P>
<P>If you want, you can specifically set the mail server name (such as mail.mycompany.com),
but it isn't usually necessary. If you specify an incorrect mail server, you get
an ESockError exception. The Port property is used to specify the port on which to
connect. The default SMTP port is port 25. The Port property defaults to a value
of 25, so you shouldn't have to change this property.</P>
<P>All the pertinent information for the mail message itself is contained in the
PostMessage property. This property is a class that contains properties such as ToAddress,
FromAddress, Subject, Body, and so on. You fill in the appropriate fields of the
PostMessage property and then send the message.</P>
<P>Before you can send a mail message, you need to connect to the SMTP server. This
is done with the Connect method:</P>
<P>
<PRE>SMTP.Host := `mail';
SMTP.Connect;
</PRE>
<P>After you're connected, you can send the email. The OnConnect event handler is
a good place for this code because you know that you are connected to an SMTP server.
For example:</P>
<P>
<PRE>procedure TMainForm.SMTPConnect(Sender: TObject);
begin
  with SMTP.PostMessage do begin
    FromAddress := `[e-mail]';
    ToAddress.Add(`[e-mail]');
    Subject := `Test';
    Body.Add(`This is a test');
  end;
  SMTP.SendMail;
end;
</PRE>
<P>This code sets up the FromAddress, ToAddress, Subject, and Body parameters of
the PostMessage property and then sends the message with the SendMail method. It's
as simple as that. Notice that the ToAddress and Body properties of PostMessage are
TStringLists. The mail message body can contain several lines of text, so it's not
surprising that the Body property is a TStringList. The ToAddress property is also
a TStringList, so you can specify several recipients for the message.</P>


<BLOCKQUOTE>
	<P>
<HR>
<strong>NOTE:</strong> The FromAddress and ToAddress fields are required fields. All other
	fields (even the message body) are optional. 
<HR>


</BLOCKQUOTE>

<P>After you know the message has been sent successfully, you can disconnect from
the SMTP server. The OnSuccess event is generated when the mail has been sent. Your
OnSuccess event handler might be as simple as the following:</P>

<DL>
	<DD>void __fastcall tform1.smtpsuccess(tobject *sender then<BR>
	begin<BR>
	SMTP.Disconnect;<BR>
	end;
</DL>

<PRE></PRE>
<P>You can send several messages per connection, of course. If you have several messages
to send, you don't have to disconnect from the server and reconnect for each message.
Just connect once, send all your messages, and then disconnect from the server.</P>
<P>Your mail message might go through without incident, or it might fail in one way
or another. In either case, you must be prepared to disconnect from the server. The
OnFailure event is generated if the mail message fails to go through, so you can
use that event to disconnect from the server as well as the OnSuccess event. The
book's code, found at http://www.mcp.com/info, contains a simple mail program that
illustrates how to send mail with TNMSMTP.</P>
<P>
<H2><A NAME="Heading9"></A>Deploying Internet Applications</H2>
<P>If your Internet application uses only the VCL Internet components, there is nothing
special to do when you deploy your application unless you are using runtime packages.
If you are using runtime packages, you need to ship INET40.BPL, and if you are using
the page producer components, ship INETDB40.BPL as well.</P>
<P>Deploying an application that uses ActiveX controls, however, requires more work.
ActiveX controls must be registered on the machine on which your application will
run. The easiest way to register ActiveX controls is with a good installation program.
InstallShield Express comes with Delphi Professional and Client/Server versions,
so you should try that program. Another good installation program is Wise Install
from Great Lakes Business Solutions. The better installation programs register, as
part of the installation process, the ActiveX controls that your application uses.</P>
<P>If you don't use a commercial installation program, you have to manually register
any ActiveX controls your application uses. The TREGSVR.EXE utility is used to register
and unregister ActiveX and OCX controls. This utility is in your Delphi 4\Bin directory.
For example, to install the EZ Web Browser application you created earlier today,
you ship the following files:</P>
<P>
<PRE>HTML.OCX
NMOCOD.DLL
NMSCKN.DLL
NWM3VWN.DLL
NMORENU.DLL
WEBBROWS.EXE
</PRE>
<P>After you install all these files, you have to run TREGSVR.EXE on the HTML.OCX
and NMOCOD.DLL files to register them. From the command line, you type</P>
<P>
<PRE>TREGSVR HTML.OCX
</PRE>
<P>Do the same for NMOCOD.DLL. The THTML control is now registered on your user's
machine and your program will run as intended.</P>


<BLOCKQUOTE>
	<P>
<HR>
<strong>NOTE:</strong> If you don't register your ActiveX controls properly, your users
	will see a message box that says, &quot;Class not registered.&quot; when they attempt
	to run your program. Your application will then terminate, leaving your users wondering
	what went wrong. 
<HR>


</BLOCKQUOTE>

<P>To unregister a control, use the /u switch as follows:</P>
<P>
<PRE>TREGSVR /u HTML.OCX
</PRE>
<P>Here again, a good installation program will have an uninstall option that takes
care of this for you.</P>
<P>As you can see, ActiveX controls require a bit of work to install after your application
is built. If you aren't aware of the fact that you need to register the ActiveX controls,
it can lead to confusion for both you and your users. By the way, the files needed
to deploy an application using the THTML control total about 900KB, so using ActiveX
controls can be expensive in terms of disk space. I prefer to use native VCL controls
whenever possible for exactly this reason.</P>
<P>
<H2><A NAME="Heading10"></A>Summary</H2>
<P>Today you learned about the Internet components provided in Delphi. You built
a simple but usable Web browser with the THTML control, and you learned how to send
mail using the TNMSMTP control. Internet programming is big business right now. It
certainly can't hurt to have some Internet programming experience.</P>
<P>
<H2><A NAME="Heading11"></A>Workshop</H2>
<P>The Workshop contains quiz questions to help you solidify your understanding of
the material covered and exercises to provide you with experience in using what you
have learned. You can find the answers to the quiz questions in Appendix A, &quot;Answers
to the Quiz Questions.&quot;</P>
<P>
<H3><A NAME="Heading12"></A>Q&amp;A</H3>

<DL>
	<DT></DT>
	<DD><B>Q What components or controls should I use to create a TCP/IP client/server
	application?</B>
	<P>
	<DT></DT>
	<DD><B>A </B>Use the TClientSocket and TServerSocket components.
	<P>
	<DT></DT>
	<DD><B>Q Can I create Web pages from my database tables?</B>
	<P>
	<DT></DT>
	<DD><B>A </B>Yes. The TQueryTableProducer and TDataSetTableProducer components create
	an HTML document from a database table. You can learn more about these components
	by examining the sample projects in the Delphi 4\Demos\Webserv directory.
	<P>
	<DT></DT>
	<DD><B>Q The TNMSMTP control is for receiving mail and the TNMPOP3 control is for
	retrieving mail. Why are there two controls for email operations?</B>
	<P>
	<DT></DT>
	<DD><B>A </B>There are two controls because there are two separate mail protocols:
	one for sending mail (SMTP) and one for retrieving mail (POP3).
	<P>
	<DT></DT>
	<DD><B>Q When were most of the Internet protocols (SMTP, POP3, FTP, UDP, and so on)
	defined?</B>
	<P>
	<DT></DT>
	<DD><B>A </B>You might be surprised to learn that many protocols used in Internet
	programming have been around for 20 years or more even though the Internet is much
	younger than that. The Internet protocols were originally designed for the UNIX platform.
	<P>
</DL>

<H3><A NAME="Heading13"></A>Quiz</H3>

<DL>
	<DT></DT>
	<DD><B>1. </B>What control do you use to display Web pages?
	<P>
	<DT></DT>
	<DD><B>2. </B>What control do you use to connect to newsgroups?
	<P>
	<DT></DT>
	<DD><B>3. </B>What is the name of the method used to display an HTML document with
	the THTML control?
	<P>
	<DT></DT>
	<DD><B>4. </B>What event is generated when an HTML document has completed loading?
	<P>
	<DT></DT>
	<DD><B>5. </B>What control do you use to send email messages?
	<P>
	<DT></DT>
	<DD><B>6. </B>What control do you use to retrieve email messages?
	<P>
	<DT></DT>
	<DD><B>7. </B>What is the name of the method used to send mail with the TNMSMTP control?
	<P>
	<DT></DT>
	<DD><B>8. </B>Can you freely distribute the Internet Explorer ActiveX control?
	<P>
	<DT></DT>
	<DD><B>9. </B>What is the name of the utility used to register ActiveX controls?
	<P>
	<DT></DT>
	<DD><B>10. </B>What company provides the bulk of the Internet controls that come
	with Delphi?
	<P>
</DL>

<H2><A NAME="Heading14"></A>Exercises</H2>

<DL>
	<DT></DT>
	<DD><B>1. </B>Write an application for sending email. The application's main form
	should have fields for the <I>from</I> address, the <I>to</I> address, the mail subject,
	and the message text.
	<P>
	<DT></DT>
	<DD><B>2. </B>Add Forward and Back buttons to the EZ Web Browser application and
	make them operational.
	<P>
	<DT></DT>
	<DD><B>3. Extra Credit:</B> Add animation to the EZ Web Browser application so that
	the user can tell when the browser is loading a document.
</DL>

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