HTTP協議是一種無狀態協議，這意味著你對網站的每一個請求都是獨立的，而且因此無法通過它自身保存數據。但這種簡單性也是它在互聯網早期就廣泛傳播的原因之一。
不過，它仍然有一種方法能讓你用cookies的形式來保存請求之間的信息。這種方法使你能夠更有效率的進行會話管理和維持數據。
有兩種處理cookies的方式—服務端(php,asp等)和客戶端(javascript).在這個教程中，我們將學習到以php和javascript這兩種方式如何去創建cookies。
Cookies and php
setting cookies
在php中創建cookie你需要用到setcookie這個方法。它需要些參數(除了第一個參數是必需的，其它參數都是可選的)
復制代碼 代碼如下:
setcookie(
'pageVisits', //cookie名字，必需的
$visited, //cookie的值
time()+7*24*60*60, //過期時間,設置為一個星期
'/', //cookie可用的文件路徑
'demo.tutorialzine.com' //cookie綁定的域名
)
如果過期時間設置為0(默認設置也是0)，那麼當浏覽器重啟時cookie將會丟失。
參數'/'表示你域名下所有文件路徑cookie都可以用(當然你也可以為它設置單一的文件路徑,例：'/admin/')。
你還可以傳給個這個函數別兩個額外的參數，這裡沒有給出。它們被規定為boolean類型的。
第一個參數表示cookie僅在一個安全的HTTPS連接才運轉,而第二個參數表示不能使用javascript操作cookie。
對大多數人來說，你只需要第四個參數，剩下的就忽略了。
reading cookies
用php讀取cookie就簡單多了。所有的傳給腳本的cookies都在$_COOKIE這個超級全局數組裡。
在我們的例子裡，可以用下面的代碼來讀取cookies:
復制代碼 代碼如下:
$visits = (int)$_COOKIE['pageVisits']+1;
echo "You visited this site: ".$visits." times";
值得注意的地方是,當下一個頁面加載好時，也可以用$_COOKIE來取得你用setcookie方法設置的cookies,
你應該意識到了什麼。
deleting cookies
為了刪除cookies，僅僅需要用setcookie函數為cookies設置一個已經過去時間做為過期就行了。
復制代碼 代碼如下:
setcookie(
'pageVisits',
$visited,
time()-7*24*60*60, //設置為前一個星期，cookie將會被刪除
'/',
'demo.tutorialzine.com'
)
Cookies and jQuery
在jquery中使用cookies，你需要一個插件Cookie plugin.
Setting cookies
用Cookie plug-in設置cookies是很直觀的:
復制代碼 代碼如下:
$(document).ready(function(){
// Setting a kittens cookie, it will be lost on browser restart:
$.cookie("kittens","Seven Kittens");
// Setting demoCookie (as seen in the demonstration):
$.cookie("demoCookie",text,{expires: 7, path: '/', domain: 'demo.tutorialzine.com'});
// "text" is a variable holding the string to be saved
});
Reading cookies
讀取cookie甚至更簡單，只需要調用$.cookie()方法，給它一個cookie-name就可以了,這個方法會返回cookie的值:
復制代碼 代碼如下:
$(document).ready(function(){
// Getting the kittens cookie:
var str = $.cookie("kittens");
// str now contains "Seven Kittens"
});
Deleting cookies
刪除cookie，只需要在次使得$.cookie()方法,把第二個參數設置為null就可以了。
復制代碼 代碼如下:
$(document).ready(function(){
// Deleting the kittens cookie:
var str = $.cookie("kittens",null);
// No more kittens
});
完整例子：
demo.php
復制代碼 代碼如下:
<?php
// Always set cookies before any data or HTML are printed to the page
$visited = (int)$_COOKIE['pageVisits'] + 1;
setcookie( 'pageVisits', // Name of the cookie, required
$visited, // The value of the cookie
time()+7*24*60*60, // Expiration time, set for a week in the future
'/', // Folder path, the cookie will be available for all scripts in every folder of the site
'demo.tutorialzine.com'); // Domain to which the cookie will be locked
?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>MicroTut: Getting And Setting Cookies With jQuery & PHP | Tutorialzine demo</title>
<link rel="stylesheet" type="text/css" href="styles.css" mce_href="styles.css" />
<mce:script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.4.2/jquery.min.js" mce_src="http://ajax.googleapis.com/ajax/libs/jquery/1.4.2/jquery.min.js"></mce:script>
<mce:script type="text/javascript" src="jquery.cookie.js" mce_src="jquery.cookie.js"></mce:script>
<mce:script type="text/javascript"><!--
$(document).ready(function(){
var cookie = $.cookie('demoCookie');
// If the cookie has been set in a previous page load, show it in the div directly:
if(cookie) $('.jq-text').text(cookie).show();
$('.fields a').click(function(e){
var text = $('#inputBox').val();
// Setting a cookie with a seven day validity:
$.cookie('demoCookie',text,{expires: 7, path: '/', domain: 'demo.tutorialzine.com'});
$('.jq-text').text(text).slideDown('slow');
e.preventDefault();
});
$('#form1').submit(function(e){ e.preventDefault(); })
})
// --></mce:script>
</head>
<body>
<h1>MicroTut: Getting And Setting Cookies With jQuery & PHP</h1>
<h2>Go Back <a href="http://tutorialzine.com/2010/03/microtut-getting-setting-cookies-jquery-php/" mce_href="http://tutorialzine.com/2010/03/microtut-getting-setting-cookies-jquery-php/">To The Tutorial »</a></h2>
<div class="section">
<div class="counter"><?php echo $visited?></div>
<p>The number above indicates how many times you've visited this page (PHP cookie). Reload to test.</p>
</div>
<div class="section">
<div class="jq-text"></div>
<form action="" method="get" id="form1">
<div class="fields">
<input type="text" id="inputBox" />
<a href="">Save</a>
</div>
</form>
<p>Write some text in the field above and click Save. It will be saved between page reloads with a jQuery cookie.</p>
</div>
</body>
</html>
jquery.cookie.js
復制代碼 代碼如下:
/**
* Cookie plugin
*
* Copyright (c) 2006 Klaus Hartl (stilbuero.de)
* Dual licensed under the MIT and GPL licenses:
* http://www.opensource.org/licenses/mit-license.php
* http://www.gnu.org/licenses/gpl.html
*
*/
/**
* Create a cookie with the given name and value and other optional parameters.
*
* @example $.cookie('the_cookie', 'the_value');
* @desc Set the value of a cookie.
* @example $.cookie('the_cookie', 'the_value', { expires: 7, path: '/', domain: 'jquery.com', secure: true });
* @desc Create a cookie with all available options.
* @example $.cookie('the_cookie', 'the_value');
* @desc Create a session cookie.
* @example $.cookie('the_cookie', null);
* @desc Delete a cookie by passing null as value. Keep in mind that you have to use the same path and domain
* used when the cookie was set.
*
* @param String name The name of the cookie.
* @param String value The value of the cookie.
* @param Object options An object literal containing key/value pairs to provide optional cookie attributes.
* @option Number|Date expires Either an integer specifying the expiration date from now on in days or a Date object.
* If a negative value is specified (e.g. a date in the past), the cookie will be deleted.
* If set to null or omitted, the cookie will be a session cookie and will not be retained
* when the the browser exits.
* @option String path The value of the path atribute of the cookie (default: path of page that created the cookie).
* @option String domain The value of the domain attribute of the cookie (default: domain of page that created the cookie).
* @option Boolean secure If true, the secure attribute of the cookie will be set and the cookie transmission will
* require a secure protocol (like HTTPS).
* @type undefined
*
* @name $.cookie
* @cat Plugins/Cookie
* @author Klaus Hartl/[email protected]
*/
/**
* Get the value of a cookie with the given name.
*
* @example $.cookie('the_cookie');
* @desc Get the value of a cookie.
*
* @param String name The name of the cookie.
* @return The value of the cookie.
* @type String
*
* @name $.cookie
* @cat Plugins/Cookie
* @author Klaus Hartl/[email protected]
*/
jQuery.cookie = function(name, value, options) {
if (typeof value != 'undefined') { // name and value given, set cookie
options = options || {};
if (value === null) {
value = '';
options.expires = -1;
}
var expires = '';
if (options.expires && (typeof options.expires == 'number' || options.expires.toUTCString)) {
var date;
if (typeof options.expires == 'number') {
date = new Date();
date.setTime(date.getTime() + (options.expires * 24 * 60 * 60 * 1000));
} else {
date = options.expires;
}
expires = '; expires=' + date.toUTCString(); // use expires attribute, max-age is not supported by IE
}
// CAUTION: Needed to parenthesize options.path and options.domain
// in the following expressions, otherwise they evaluate to undefined
// in the packed version for some reason...
var path = options.path ? '; path=' + (options.path) : '';
var domain = options.domain ? '; domain=' + (options.domain) : '';
var secure = options.secure ? '; secure' : '';
document.cookie = [name, '=', encodeURIComponent(value), expires, path, domain, secure].join('');
} else { // only name given, get cookie
var cookieValue = null;
if (document.cookie && document.cookie != '') {
var cookies = document.cookie.split(';');
for (var i = 0; i < cookies.length; i++) {
var cookie = jQuery.trim(cookies[i]);
// Does this cookie string begin with the name we want?
if (cookie.substring(0, name.length + 1) == (name + '=')) {
cookieValue = decodeURIComponent(cookie.substring(name.length + 1));
break;
}
}
}
return cookieValue;
}
};
styles.css
復制代碼 代碼如下:
*{
margin:0;
padding:0;
}
body{
/* Setting default text color, background and a font stack */
color:#555555;
font-size:0.825em;
background: #fcfcfc;
font-family:Arial, Helvetica, sans-serif;
}
.section{
margin:0 auto 60px;
text-align:center;
width:600px;
}
.counter{
color:#79CEF1;
font-size:180px;
}
.jq-text{
display:none;
color:#79CEF1;
font-size:80px;
}
p{
font-size:11px;
padding:0 200px;
}
form{
margin-bottom:15px;
}
input[type=text]{
border:1px solid #BBBBBB;
color:#444444;
font-family:Arial,Verdana,Helvetica,sans-serif;
font-size:14px;
letter-spacing:1px;
padding:2px 4px;
}
/* The styles below are only necessary for the styling of the demo page: */
h1{
background:#F4F4F4;
border-bottom:1px solid #EEEEEE;
font-size:20px;
font-weight:normal;
margin-bottom:15px;
padding:15px;
text-align:center;
}
h2 {
font-size:12px;
font-weight:normal;
padding-right:40px;
position:relative;
right:0;
text-align:right;
text-transform:uppercase;
top:-48px;
}
a, a:visited {
color:#0196e3;
text-decoration:none;
outline:none;
}
a:hover{
text-decoration:underline;
}
.clear{
clear:both;
}
h1,h2,p.tutInfo{
font-family:"Myriad Pro",Arial,Helvetica,sans-serif;
}
結束語:
關於cookie的使用，你需要注意的是不要把一些敏感信息(例如用戶名、密碼)保存在cookies中，
為因當每一個頁面加載時cookies都會和headers一樣傳遞到頁面，很容易被不法份子截取到。
但是，只要有適當的預防措施，你就可以用這個簡單的技術實現大量的互動。
