ЭЛЕКТРОННАЯ БИБЛИОТЕКА КОАПП |
Сборники Художественной, Технической, Справочной, Английской, Нормативной, Исторической, и др. литературы. |
19.8. Redirecting to a Different LocationProblemYou need to tell the client's browser to look elsewhere for a page. SolutionInstead of a normal header, just issue a location redirect and exit. Don't forget the extra newline at the end of the header. $url = "http://www.perl.com/CPAN/"; print "Location: $url\n\n"; exit; DiscussionSometimes your CGI program doesn't need to generate the document on its own. It only needs to tell the client at the other end to fetch a different document instead. In that case, the HTTP header needs to include this directive as a The direct and literal solution given above is usually sufficient. But if you already have the CGI module loaded, use the Example 19.4: oreobounce#!/usr/bin/perl -w # oreobounce - set a cookie and redirect the browser use CGI qw(:cgi); $oreo = cookie( -NAME => 'filling', -VALUE => "vanilla crиme", -EXPIRES => '+3M', # M for month, m for minute -DOMAIN => '.perl.com'); $whither = "http://somewhere.perl.com/nonesuch.html"; print redirect( -URL => $whither, -COOKIE => $oreo); That would produce:
Example 19.5 is a complete program that looks at the client browser name and redirects it to a page in Eric Raymond's Jargon File that talks about the user's browser. It's also a nice example of a different approach to building a switch statement in Perl. Example 19.5: os_snipe#!/usr/bin/perl # os_snipe - redirect to a Jargon File entry about current OS $dir = 'http://www.wins.uva.nl/%7Emes/jargon'; for ($ENV{HTTP_USER_AGENT}) { $page = /Mac/ && 'm/Macintrash.html' || /Win(dows )?NT/ && 'e/evilandrude.html' || /Win|MSIE|WebTV/ && 'm/MicroslothWindows.html' || /Linux/ && 'l/Linux.html' || /HP-UX/ && 'h/HP-SUX.html' || /SunOS/ && 's/ScumOS.html' || 'a/AppendixB.html'; } print "Location: $dir/$page\n\n"; The os_snipe program shows a good use of dynamic redirection, because you don't always send every user to the same place. If you did, it would usually make more sense to arrange for a static redirect line in the server's configuration file, since that would be easier on the web server than running a CGI script for each redirection. Telling the client's browser that you don't plan to produce any output is not the same as redirecting nowhere: use CGI qw(:standard); print header( -STATUS => '204 No response' ); That produces this:
Use this, for instance, when the user will submit a form request but you don't want their page to change or even update. It may seem silly to provide a content type and then no content, but that's what the module does. If you were hand-coding this, it wouldn't be required. #!/bin/sh cat <<EOCAT Status: 204 No response EOCAT See AlsoThe documentation for the standard CGI module |