php中使用__autoload()自动加载未定义类的实现代码

<?php
/**
* 自动加载相关类库文件
*/
function __autoload($classname){
if(substr($classname,-6)=="action"){
include app_path.'controllers/'.$classname.'.class.php';
}elseif(substr($classname, -5)=="model"){
include app_path.'models/'.$classname.'.class.php';
}elseif($classname=="smarty"){
include system_path.'smarty/smarty.class.php';
}else{
include app_path.'common/'.$classname.'.class.php';
}
}
?>

<?php
function __autoload($class_name) {
$path = str_replace('_', directory_separator, $class_name);
require_once $path.'.php';
}
?>