PHP simply uses token to prevent repeated submission of forms

<?php
/*
* PHP简单利用token防止表单重复提交
* 此处理方法纯粹是为了给初学者参考
*/
session_start();
function set_token() {
$_SESSION[&#39;token&#39;] = md5(microtime(true));
}
function valid_token() {
$return = $_REQUEST[&#39;token&#39;] === $_SESSION[&#39;token&#39;] ? true : false;
set_token();
return $return;
}
//如果token为空则生成一个token
if(!isset($_SESSION[&#39;token&#39;]) || $_SESSION[&#39;token&#39;]==&#39;&#39;) {
set_token();
}
if(isset($_POST[&#39;test&#39;])){
if(!valid_token()){
echo "token error";
}else{
echo &#39;成功提交，Value:&#39;.$_POST[&#39;test&#39;];
}
}
?>
<form method="post" action="">
<input type="hidden" name="token" value="<?php echo $_SESSION[&#39;token&#39;]?>">
<input type="text" name="test" value="Default">
<input type="submit" value="提交" />
</form>