解析php类的注册与自动加载

工程目录如下：1、将需要注册的类放在一个数组中
复制代码 代码如下:
<?php
final class Utils {
    private function __construct() {
    }
    public static function getClasses($pre_path = "/") {
        $classes = array(
                "DBConfig" => $pre_path."DBConfig/DBConfig.php",
                "User" => $pre_path."Model/User.php",
                "Dao" => $pre_path."Dao/Dao.php",
                "UserDao" => $pre_path."Dao/UserDao.php",
                "UserMapper" => $pre_path."Mapping/UserMapper.php",
        );
        return $classes;
    }
}
?>

2、注册数组
注意：步骤1中的类的路径都是相对于init.php而言的，不是相对于Utils而言的，这是因为我们通过init.php里的自动加载函数spl_autoload_register来require类的
复制代码 代码如下:
<?php
require_once "/Utils/Utils.php";
final class Init {    /**
     * System config.
     */
    public function init() {
        // error reporting - all errors for development (ensure you have
        // display_errors = On in your php.ini file)
        error_reporting ( E_ALL | E_STRICT );
        mb_internal_encoding ( "UTF-8" );
        //registe classes
        spl_autoload_register ( array ($this,"loadClass" ) );
    }    /**
     * Class loader.
     */
    public function loadClass($name) {
        $classes = Utils::getClasses ();
        if (! array_key_exists ( $name, $classes )) {
            die ( "Class "" . $name . "" not found." );
        }
        require_once $classes [$name];
    }
}
$init = new Init ();
$init->init ();
?>

3、本例中在使用处test.php里require init.php
复制代码 代码如下:
<?php
require_once "Init.php";
$dao = new UserDao();
$result = $dao->findByName("zcl");
?>