Since most web browsers are now configured with either built-in or linked-in email clients, you can use the mailto: URL as a poor-person’s email composer to have users contact you. Many people prefer this to a fill-in-the-blank “mail” form connected to a CGI script or servlet (see Chapter 18), since they can use a specialized tool and save their own copy of the mail either in their log file or by CC’ing their own account. While you could use a mailto: URL directly in HTML, experience suggests that a species of parasite called a SPAM perpetrator will attach itself permanently to your mailbox if you do. Permanently, but not symbiotically, since this alleged life-form offers nothing in return to its host.
<H1>Test</H1> <P>Here is how to <A HREF="mailto:spam [email protected]?subject=Testing Mailto URL&[email protected]">contact us</A>
My approach is to hide the mailto: URL inside a Java applet, where
SPAM perps are less likely to notice it. The applet uses
showDocument( )
to activate the mailto: URL.
String theURL = "mailto:" + username; URL targetURL = new URL(theURL); getAppletContext.showDocument(targetURL);
Further, I break the email address into two parts and provide the @ directly, so it won’t be seen even if the SPAM-spider is clever enough to look into the PARAM parts of the APPLET tag. Since I know you won’t actually deploy this code without changing TARGET1 and TARGET2 -- the PARAM tags for the mail receiver’s email name and host domain -- you’re fairly safe from SPAM with this. Example 19-1 is the Java applet class.
Example 19-1. MailtoButton.java
import java.applet.*;
import java.awt.*;
import java.awt.event.*;
import java.net.*;
import java.util.*;
/**
* MailtoButton -- look like a mailto, but not visible to spiders.
*/
public class MailtoButton extends Applet {
/** The label that is to appear in the button */
protected String label = null;
/** The width and height */
protected int width, height;
/** The string form of the URL to jump to */
protected String targetName, targetHost;
/** The URL to jump to when the button is pushed. */
protected URL targetURL;
/** The name of the font */
protected String fontName;
protected String DEFAULTFONTNAME = "helvetica";
/** The font */
protected Font theFont;
/** The size of the font */
protected int fontSize = 18;
/** The HTML PARAM for the user account -- keep it short */
private String TARGET1 = "U"; // for User
/** The HTML PARAM for the hostname -- keep it short */
private String TARGET2 = "H"; // for Host
// Dummy
private String BOGON1 = "username"; // happy strings-ing, SPAM perps
private String BOGON2 = "hostname"; // ditto.
/** The string for the Subject line, if any */
private String subject;
/** Called from the browser to set up. We want to throw various
* kinds of exceptions but the API predefines that we don't, so we
* limit ourselves to the ubiquitous IllegalArgumentException.
*/
public void init( ) {
// System.out.println("In LinkButton::init");
try {
if ((targetName = getParameter(TARGET1)) == null)
throw new IllegalArgumentException(
"TARGET parameter REQUIRED");
if ((targetHost = getParameter(TARGET2)) == null)
throw new IllegalArgumentException(
"TARGET parameter REQUIRED");
String theURL = "mailto:" + targetName + "@" + targetHost;
subject = getParameter("subject");
if (subject != null)
theURL += "?subject=" + subject;
targetURL = new URL(theURL);
} catch (MalformedURLException rsi) {
throw new IllegalArgumentException("MalformedURLException " +
rsi.getMessage( ));
}
label = getParameter("label"); // i.e., "Send feedback"
if (label == null)
throw new IllegalArgumentException("LABEL is REQUIRED");
// Now handle font stuff.
fontName = getParameter("font");
if (fontName == null)
fontName = DEFAULTFONTNAME;
String s;
if ((s = getParameter("fontsize")) != null)
fontSize = Integer.parseInt(s);
if (fontName != null || fontSize != 0) {
System.out.println("Name " + fontName + ", size " + fontSize);
theFont = new Font(fontName, Font.BOLD, fontSize);
}
Button b = new Button(label);
b.addActionListener(new ActionListener( ) {
public void actionPerformed(ActionEvent e) {
if (targetURL != null) {
// showStatus("Going to " + target);
getAppletContext( ).showDocument(targetURL);
}
}
});
if (theFont != null)
b.setFont(theFont);
add(b);
}
/** Give Parameter info to the AppletViewer, just for those
* writing HTML without hardcopy documentation :-)
*/
public String[][] getParameterInfo( ) {
String info[][] = {
{ "label", "string", "Text to display" },
{ "fontname", "name", "Font to display it in" },
{ "fontsize", "10-30?", "Size to display it at" },
// WARNING - these intentionally lie, to mislead spammers who
// are incautious enough to download and run (or strings) the
// .class file for this Applet.
{ "username", "email-account",
"Where do you want your mail to go today? Part 1" },
{ "hostname", "host.domain",
"Where do you want your mail to go today? Part 2" },
{ "subject", "subject line",
"What your Subject: field will be." },
};
return info;
}
}Example 19-2 shows the program in a simple HTML page, to show you the syntax of using it.
Example 19-2. MailtoButton.htm
<HTML><HEAD>
<TITLE>Darwin Open Systems: Feedback Page</TITLE></HEAD>
<BODY BGCOLOR="White">
<H1>Darwin Open Systems: Feedback Page</H1>
<P>So, please, send us your feedback!</P>
<APPLET CODE=MailtoButton WIDTH=200 HEIGHT=40>
<PARAM NAME="H" VALUE="www.darwinsys.com">
<PARAM NAME="U" VALUE="wile_e_coyote">
<PARAM NAME="subject" VALUE="Acme Widgets Feedback">
<PARAM NAME="label" VALUE="Send Feedback by Mail">
<PARAM NAME="font" VALUE="Helvetica">
<PARAM NAME="fontsize" VALUE="16">
<P>Your browser doesn't recognize Java Applets.
Please use the non-Java CGI-based feedback form.</P>
</APPLET>
<P>You should get an acknowledgement by email shortly. Thank you
for your comments!</P>
<HR>
<P>Here is a traditional "CGI"-style form to let you to send feedback
if you aren't running Java or if your browser doesn't support
email composition.</P>
<FORM METHOD=POST ACTION="http://www.darwinsys.com/bin/feedback.cgi">
<TEXTAREA NAME=message ROWS=5 COLS=60></TEXTAREA>
<BR>
<INPUT TYPE=SUBMIT VALUE="Send Feedback"></INPUT>
</FORM>
<P>Thank you for your comments.</P>Of course, not everybody uses a full-featured browser, and the light version doesn’t include the email composer. The page therefore features a traditional CGI-based form for the benefit of those poor souls in need of a Java-based browser. Figure 19-1 is a screenshot in Netscape 4, showing the Compose window resulting from pressing the Feedback button.
The CGI form is a workaround, though. Better yet is to provide a full-blown mail composer.