依赖注入学习-01

<?php

/*
    无Di容器的写法

    class example {
        private $_db;
        function getList(){
            $this->_db->query("......");//这里具体sql语句就省略不写了
        }
        //从外部注入db连接
        function setDb($connection){
            $this->_db = $connection;
        }
    }
    //调用
    $example = new example();
    $example->setDb(Factory::getDb());//注入db连接
    $example->getList();

    class Factory {
        public static function getExample(){
            $example = new example();
            $example->setDb(Factory::getDb());//注入db连接
            $example->setFile(Factory::getFile());//注入文件处理类
            $example->setImage(Factory::getImage());//注入Image处理类
            return $expample;
        }
    }
    实例化example时变为
    $example=Factory::getExample();
    $example->getList();
*/

header("Content-Type:text/html;charset=utf-8");

class Di{
    private $_factory;
    public function set($id,$value){
        $this->_factory[$id] = $value;
    }

    public function get($id){
        $value = $this->_factory[$id];
        return $value();
    }
}

class User{
    private $_username;
    function __construct($username="") {
        $this->_username = $username;
    }
    function getUserName(){
        return $this->_username;//$this->_username = $username;
    }
}

$di = new Di();
$di->set("zhangsan",function(){
    return new User(‘张三‘);
}); //$this->_factory[‘zhangsan‘] = new User(‘张三‘);

$di->set("lisi",function(){
   return new User("李四");
}); //$this->_factory[‘lisi‘] = new User(‘李四‘);

echo $di->get("zhangsan")->getUserName();// $value = $this->_factory[‘zhangsan‘] = new User(‘张三‘)->getUserName();
echo $di->get("lisi")->getUserName();// $value = $this->_factory[‘lisi‘] = new User(‘李四‘)->getUserName();

/* $data = new User(‘张三‘);
echo $data->getUserName(); */