PHP防止刷新重复提交页面的示例代码

if (isset($_POST['action']) && $_POST['action'] == 'submitted') { 
session_start(); 
if (isset($_SESSION['submit_time']) && $_SESSION['submit_time']==0){ 
print '<pre>'; 
print_r($_POST); 
print '<a href="'. $_SERVER['PHP_SELF'] .'">Please try again</a>'; 
print '</pre>'; 
$_SESSION['submit_time']=1; 
echo $_SESSION['submit_time']; 
unset($_SESSION['submit_time']);
} else { 
print '<pre>'; 
print_r($_POST); 
echo "However you have submitted"; 
print '</pre>'; 
} 
} else { 
session_start() or dir("session is not started"); 
$_SESSION['submit_time']= 0; 
// isset($_SESSION['submit_time']) or die ("session var is not created"); 
// echo $_SESSION['submit_time']; 
?> 
<form action="<?php echo $_SERVER['PHP_SELF']; ?>" method="POST"> 
Name: <input type="text" name="personal[name]"><br> 
Email: <input type="text" name="personal[email]"><br> 
Beer: <br> 
<select multiple name="beer[]"> 
<option value="warthog">Warthog</option> 
<option value="guinness">Guinness</option> 
</select><br> 
<input type="hidden" name="action" value="submitted"> 
<input type="submit" name="submit" value="submit me!"> 
</form> 
<?php 
} 
?>