在每一个 PHP 文档中访问一个唯一的会话标识符只是会话功能的开始。当一个会话启动后，我们可以在超全局变量 $_SESSION 中存储任意多个变量，然后在任何支持会话的页面上访问它们。
下面程序向超全局变量 $_SESSION 添加了两个变量：
复制代码 代码如下:
<?php
session_start ();
$_SESSION [ "product1" ] = "Sonic Screwdriver" ;
$_SESSION [ "product2" ] = "HAL 2000" ;
echo "The products have been registered." ;
?>
在用户移动到一个新的页面之前，上面程序的神奇之处不会体现出来。下面的程序创建了一个单独的 PHP 脚本，这个脚本访问存储在超全局变量 $_SESSION 中的变量。
复制代码 代码如下:
<?php
session_start ();
echo "Your chosen products are:" ;
echo "<ul>" ;
echo "<li>" . $_SESSION [ "product1" ]. "</li>" ;
echo "<li>" . $_SESSION [ "product2" ]. "</li>" ;
echo "</ul>" ;
?>
下列程序清单创建一个表单，它允许一个用户来选择多个产品。我们可以使用会话变量来创建一个基本的购物车。
arraysession.php:
复制代码 代码如下:
<?php
session_start ();
?>
<html>
<head>
<title> Storing an array with a session </title>
</head>
<body>
<h1> Product Choice Page </h1>
<?php
if ( isset ( $_POST [ "form_products" ])){
if (! empty ( $_SESSION [ "products" ])){
$products = array_unique (
array_merge ( unserialize ( $_SESSION [ "products" ]),
$_POST [ "form_produces" ]));
}
else
{
$_SESSION [ "products" ] = serialize ( $_POST [ "form_products" ]);
}
echo "<p>Your products have been registered!</p>" ;
}
?>
<form method = "POST" action = " <?php echo $_SERVER [ "PHP_SELF" ]; ?> " >
<p><strong> Select some products: </strong><br>
<select name = "form_product[]" multiple = "multiple" size = "3" >
<option value = "Sonic Screwdriver" > Sonic Screwdriver </option>
<option value = "Hal 2000" > Hal 2000 </option>
<option value = "Tardis" > Tardis </option>
<option value = "ORAC" > ORAC </option>
<option value = "Transporter bracelet" > Transporter bracelet </option>
</select>
<p><input type = "submit" value = "choose" /></p>
</form>
<p><a href = "session1.php" > go to content page </a></p>
</body>
</html>
session1.php:
复制代码 代码如下:
<?php
/*
* Created on 2011-1-19
*
* To change the template for this generated file go to
* Window - Preferences - PHPeclipse - PHP - Code Templates
*/
session_start ();
?>
<html>
<head>
<title> Accessing session variables </title>
</head>
<body>
<h1> Content Page </h1>
<?php
if ( isset ( $_SESSION [ "products" ])){
echo "<strong>Your cart:</strong><ol>" ;
foreach ( unserialize ( $_SESSION [ "products" ]) as $p ){
echo "<li>" . $p . "</li>" ;
}
echo "</ol>" ;
}
?>
<p><a href = "arraysession.php" > return to product choice page </a></p>
</body>
</html>
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7.销毁会话和重置变量
8.在一个带有注册用户的环境中使用会话