代理模式

$proxy = new \IMooc\Proxy();
$proxy->getUserName($id);
$proxy->setUserName($id, $name);

<?php
namespace IMooc;

interface IUserProxy
{
    function getUserName($id);
    function setUserName($id, $name);
}

<?php
namespace IMooc;

class Proxy implements IUserProxy
{

    function getUserName($id)
    {
        $db = Factory::createDatabase(‘slave‘);
        $db->query("select name from user where id = $id limit 1");
    }

    function setUserName($id, $name)
    {
        $db = Factory::createDatabase(‘master‘);
        $db->query("update user set name = $name where id = $id limit 1");
    }
}