代码：
a. 入口文件：index.php
<?php
namespace Index;
use auto\say;
use auto\mycolor\color;
function my_autoload($name){
$name = str_replace('\\',DIRECTORY_SEPARATOR,$name);
require $name.'.class.php';
}
spl_autoload_register(__NAMESPACE__.'\\my_autoload');
$say = new say();
$say->hello();
$color = new color();
$color->test();
b. auto/say.class.php：
<?php
namespace auto;
class say{
public function hello(){
echo "hello";
}
}
c. auto/mycolor/color.class.php：
<?php
namespace auto\mycolor;
class color{
public function test(){
echo "blue";
}
}