jQuery
HTTP协议是一种无状态协议，这意味着你对网站的每一个请求都是独立的，而且因此无法通过它自身保存数据。但这种简单性也是它在互联网早期就广泛传播的原因之一。
不过，它仍然有一种方法能让你用cookies的形式来保存请求之间的信息。这种方法使你能够更有效率的进行会话管理和维持数据。
有两种处理cookies的方式—服务端(php,asp等)和客户端(javascript).在这个教程中，我们将学习到以php和javascript这两种方式如何去创建cookies。
Cookies and php
setting cookies
在php中创建cookie你需要用到setcookie这个方法。它需要些参数(除了第一个参数是必需的，其它参数都是可选的)
代码如下:
setcookie(
'pageVisits', //cookie名字，必需的
$visited, //cookie的值
time()+7*24*60*60, //过期时间,设置为一个星期
'/', //cookie可用的文件路径
'demo.tutorialzine.com' //cookie绑定的域名
)
如果过期时间设置为0(默认设置也是0)，那么当浏览器重启时cookie将会丢失。
参数'/'表示你域名下所有文件路径cookie都可以用(当然你也可以为它设置单一的文件路径,例：'/admin/')。
你还可以传给个这个函数别两个额外的参数，这里没有给出。它们被规定为boolean类型的。
第一个参数表示cookie仅在一个安全的HTTPS连接才运转,而第二个参数表示不能使用javascript操作cookie。
对大多数人来说，你只需要第四个参数，剩下的就忽略了。
reading cookies
用php读取cookie就简单多了。所有的传给脚本的cookies都在$_COOKIE这个超级全局数组里。
在我们的例子里，可以用下面的代码来读取cookies:
代码如下:
$visits = (int)$_COOKIE['pageVisits']+1;
echo "You visited this site: ".$visits." times";
值得注意的地方是,当下一个页面加载好时，也可以用$_COOKIE来取得你用setcookie方法设置的cookies,
你应该意识到了什么。
deleting cookies
为了删除cookies，仅仅需要用setcookie函数为cookies设置一个已经过去时间做为过期就行了。
代码如下:
setcookie(
'pageVisits',
$visited,
time()-7*24*60*60, //设置为前一个星期，cookie将会被删除
'/',
'demo.tutorialzine.com'
)
Cookies and jQuery
在jquery中使用cookies，你需要一个插件Cookie plugin.
Setting cookies
用Cookie plug-in设置cookies是很直观的:
代码如下:
$(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):
$.cookie("demoCookie",text,{expires: 7, path: '/', domain: 'demo.tutorialzine.com'});
// "text" is a variable holding the string to be saved
});
Reading cookies
读取cookie甚至更简单，只需要调用$.cookie()方法，给它一个cookie-name就可以了,这个方法会返回cookie的值:
代码如下:
$(document).ready(function(){
// Getting the kittens cookie:
var str = $.cookie("kittens");
// str now contains "Seven Kittens"
});
Deleting cookies
删除cookie，只需要在次使得$.cookie()方法,把第二个参数设置为null就可以了。
代码如下:
$(document).ready(function(){
// Deleting the kittens cookie:
var str = $.cookie("kittens",null);
// No more kittens
});
完整例子：
demo.php
代码如下:
// 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
?>
MicroTut: Getting And Setting Cookies With jQuery & PHP | Tutorialzine demoMicroTut: Getting And Setting Cookies With jQuery & PHP
Go Back To The Tutorial »
The number above indicates how many times you've visited this page (PHP cookie). Reload to test.
Write some text in the field above and click Save. It will be saved between page reloads with a jQuery cookie.
jquery.cookie.js
代码如下:
/**
* 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/klaus.hartl@stilbuero.de
*/
/**
* 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/klaus.hartl@stilbuero.de
*/
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
代码如下:
*{
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;
}
结束语:
关于cookie的使用，你需要注意的是不要把一些敏感信息(例如用户名、密码)保存在cookies中，
为因当每一个页面加载时cookies都会和headers一样传递到页面，很容易被不法份子截取到。
但是，只要有适当的预防措施，你就可以用这个简单的技术实现大量的互动。
