一 CGI.pm中的方法（routines）调用
1. CGI.pm实现了两种使用方法，分别是面向对象的方式和传统的perlmodule方法的方式。
面向对象的方式：
#!/usr/local/bin/perl -w
use CGI; # load CGI routines
$q = CGI->new; # create new CGI object
print $q->header, # create the HTTP header
$q->start_html('hello world'), # start the HTML
$q->h1('hello world'), # level 1 header
$q->end_html; # end the HTML
传统的module方法的方式：
#!/usr/local/bin/perl
use CGI qw/:standard/; # load standard CGI routines
print header, # create the HTTP header
start_html('hello world'), # start the HTML
h1('hello world'), # level 1 header
end_html; # end the HTML
2. CGI.pm中的方法。
CGI.pm中的方法，通常有很多的参数，所以一般我们使用命名参数的方式来调用，例如：
print $q->header(-type=>'image/gif',-expires=>'+3d');
命名参数的值可以为scalar或array reference类型，例如：
$q->param(-name=>'veggie',-value=>'tomato');
$q->param(-name=>'veggie',-value=>['tomato','tomahto','potato','potahto']);
3. CGI.pm中的html元素（html shortcuts）方法
所有的html的元素（例如h1，br等）在CGI.pm中都有对应的方法，这些方法根据需要动态的生成，且都包含2个参数，第一个参数为hash类型，对应html元素的属性，第二个参数的string类型，对应html元素的内容。例如html中的h1对应的方法为h1( )：
Code Generated HTML
---- --------------
h1() <h1>
h1('some','contents'); <h1>some contents</h1>
h1({-align=>left}); <h1 align="LEFT">
h1({-align=>left},'contents'); <h1 align="LEFT">contents</h1>
有时你想自己处理元素的开始和结尾，则可以使用start_tag_name和end_tag_name,例如
print start_h1,'Level 1 Header',end_h1;
有的时候start和end方法没有被自动生成，需要显示的指定，例如：
use CGI qw/:standard *table start_ul/;
用来自动生成start_table,end_table,start_ul和end_ul方法。
另一个实例：
print a({-href=>'fred.html',-target=>'_new'}, "Open a new frame");
<a href="fred.html",target="_new">Open a new frame</a>
二 CGI.pm中获取cgi的参数
@names = $query->param #get all params
@values = $query->param('foo'); #get param foo as list
$value = $query->param('foo'); #get param foo as scalar
param()获取参数的结果可以为scalar或array类型，例如当参数的结果来自多选的scrollinglist的时候就为array类型。如果参数的值在querystring中没有给定（"name1=&name2="），param()将返回emptystring。如果参数在querystring中根本不存在，则param()则返回undef或emptylist。当参数为多个值时querystring中写法为var1=value1&var1=value2&var1=value3.
三 header and start_html
1. header指定html的header，例如
print header; # 返回默认的type：text/html
print header('image/gif'); #设定type为：image/gif
print header('text/html','204 No response');
$cookie1 = $q->cookie(-name=>'riddle_name', -value=>"The Sphynx's Question");
$cookie2 = $q->cookie(-name=>'answers', -value=>\%answers);
print header(-type=>'image/gif',
-nph=>1,
-status=>'402 Payment required',
-expires=>'+3d',
-cookie => [$cookie1,$cookie2] ,
-charset=>'utf-7',
-attachment=>'foo.gif',
-Cost=>'$2.00');
其中-type,-status,-expires,-cookie为可以设别的参数，其他的命名参数都被转化为html header属性。
-expires的值可以为：
+30s 30 seconds from now
+10m ten minutes from now
+1h one hour from now
-1d yesterday (i.e. "ASAP!")
now immediately
+3M in three months
+10y in ten years time
Thursday, 25-Apr-1999 00:40:33 GMT at the indicated time & date
2. start_html 创建页面的顶层元素<html><header</header><body>
例如：
print start_html(-title=>'Secrets of the Pyramids',
-author=>'fred@jbxue.org',
-base=>'true',
-target=>'_blank',
-meta=>{'keywords'=>'pharaoh secret mummy',
'copyright'=>'copyright 1996 King Tut'},
-style=>{'src'=>'/styles/style1.css'},
-BGCOLOR=>'blue');
或者：
print start_html(-head=>[
Link({-rel=>'shortcut icon',href=>'favicon.ico'}),
meta({-http_equiv => 'Content-Type',-content=> 'text/html'})
]
);
在header中加入javascript的例子：
$query = CGI->new;
print header;
$JSCRIPT=<<END;
// Ask a silly question
function riddle_me_this() {
var r = prompt("What walks on four legs in the morning, " +
"two legs in the afternoon, " +
"and three legs in the evening?");
response(r);
}
// Get a silly answer
function response(answer) {
if (answer == "man")
alert("Right you are!");
else
alert("Wrong! Guess again.");
}
END
print start_html(-title=>'The Riddle of the Sphinx',
-script=>$JSCRIPT);
print $q->start_html(-title=>'The Riddle of the Sphinx',
-script=>{-type=>'JAVASCRIPT',
-src=>'/javascript/sphinx.js'}
);
print $q->start_html(-title=>'The Riddle of the Sphinx',
-script=>[
{ -type => 'text/javascript',
-src => '/javascript/utilities10.js'
},
{ -type => 'text/javascript',
-src => '/javascript/utilities11.js'
},
{ -type => 'text/jscript',
-src => '/javascript/utilities12.js'
},
{ -type => 'text/ecmascript',
-src => '/javascript/utilities219.js'
}
]
);
在header中使用css的例子：
use CGI qw/:standard :html3/;
#here's a stylesheet incorporated directly into the page
$newStyle=<<END;
<!--
P.Tip {
margin-right: 50pt;
margin-left: 50pt;
color: red;
}
P.Alert {
font-size: 30pt;
font-family: sans-serif;
color: red;
}
-->
END
print header();
print start_html( -title=>'CGI with Style',
-style=>{-src=>'http://www.zzvips.com/style/st1.css',
-code=>$newStyle}
);
print h1('CGI with Style'),
p({-class=>'Tip'},
"Better read the cascading style sheet spec before playing with this!"),
span({-style=>'color: magenta'},
"Look Mom, no hands!",
p(),
"Whooo wee!"
);
print end_html;
四 url
$full_url = url(); # http://your.host.com/path/to/script.cgi
$full_url = url(-full=>1); # http://your.host.com/path/to/script.cgi
$relative_url = url(-relative=>1); #script.cgi
$absolute_url = url(-absolute=>1); #path/to/script.cgi
$url_with_path = url(-path_info=>1);
$url_with_path_and_query = url(-path_info=>1,-query=>1);
$netloc = url(-base => 1); #http://your.host.com
五 CGI.pm中的html元素方法的特殊用法
如果元素的第二个参数为list类型，则会被分解，例如：
print ul(
li({-type=>'disc'},['Sneezy','Doc','Sleepy','Happy'])
);
相当于：
<ul>
<li type="disc">Sneezy</li>
<li type="disc">Doc</li>
<li type="disc">Sleepy</li>
<li type="disc">Happy</li>
</ul>
例如table可以写为：
print table({-border=>undef},
caption('When Should You Eat Your Vegetables?'),
Tr({-align=>'CENTER',-valign=>'TOP'},
[
th(['Vegetable', 'Breakfast','Lunch','Dinner']),
td(['Tomatoes' , 'no', 'yes', 'yes']),
td(['Broccoli' , 'no', 'no', 'yes']),
td(['Onions' , 'yes','yes', 'yes'])
]
)
);
六 CGI.pm中非标准的html元素方法
print comment('here is my comment'); #generates an HTML comment (<!-- comment -->)
因为与perl方法冲突，所以大写的:
Select
Tr
Link
Delete
Accept
Sub
其他特殊的html元素方法：start_html(), end_html(), start_form(), end_form(), start_multipart_form() and all the fill-out form tags。
七 CGI.pm中的form相关
1 start_form 和start_multipart_form
print start_form(-method=>$method,
-action=>$action,
-enctype=>$encoding);
<... various form stuff ...>
print end_form;
-or-
print start_form($method,$action,$encoding);
<... various form stuff ...>
print end_form;
如果没有指定method，action，enctype，默认地为：
method: POST
action: this script
enctype: application/x-www-form-urlencoded for non-XHTML
multipart/form-data for XHTML, see multipart/form-data below.
当使用start_form的时候，enctype为application/x-www-form-urlencoded，如果需要新式的xhtml，则需要使用start_multipart_form,此时enctype为multipart/form-data。
更多内容请参考：cgi man page http://search.cpan.org/~markstos/CGI.pm-3.60/lib/CGI.pm