PHP 依賴注入

一般調用一個類裏面的方法須要如何操做：

$class = new class();
$class->fun()

依賴注入模式用來減小程序間的耦合

依賴注入共有三種模式：

setter 方法注入

着重說下setter方法注入並結合ArrayAccess

/**
 * Class Di
 * @property People
 */
class Di implements ArrayAccess
{
    /**
     * 單例
     * @var null
     */
    protected static $instance = null;

    /**
     * 註冊的服務
     * @var array
     */
    protected $data = array();

    public function __construct()
    {
        echo '__construct'. "\n";
    }

    public function onConstruct(){
        echo 'onConstruct'. "\n";
    }

    public static function one(){
        if (self::$instance == null) {
            self::$instance = new Di();
            self::$instance->onConstruct();
        }
        return self::$instance;
    }

    public function get($name, $default = NULL) {
        if (!empty($default)) {
            return $default;
        }

        return $this->data[$name];
    }

    public function set($name, $value) {
        $this->data[$name] = $value;
    }

    public function __get($name)
    {
        return $this->get($name);
    }

    public function __set($name, $value)
    {
        $this->set($name, $value);
    }


    /** ArrayAccess數組訪問接口 **/

    public function offsetSet($offset, $value) {
        $this->set($offset, $value);
    }

    public function offsetGet($offset) {
        return $this->get($offset, NULL);
    }

    public function offsetUnset($offset) {
        unset($this->data[$offset]);
    }

    public function offsetExists($offset) {
        return isset($this->data[$offset]);
    }

}

class People {

    protected $name = '測試';
    public function getName(){
        return $this->name;
    }

}

class Email {

    public function sendEmail($email){
        return '郵件發送成功！';
    }

}

$di = Di::one();
/** @var get set 方式訪問 people */
$di->people = new People();
$people = $di->people;
echo $di->people->getName();

/** 經過數組的方式訪問 **/
$di['Email'] = new Email();
echo $di['Email']->sendEmail('33@qq.com');

Phalapi也是經過該方式實現依賴注入
依賴注入至關於一個註冊中心，經過魔術方法__set __get進行賦值和取之操做，$di->email
implements ArrayAccess 能夠實現經過數組的方式進行操做$di['Email']

構造方法注入

經過__construct出入類

class a
{
    public function test() {
        echo 'test';
    }
}

class c
{
    protected $s;
    public function __construct($a)
    {
        $this->s = $a;
    }

    public function test(){
        $this->s->test();
    }
}

$a = new a();
$c = new c($a);
$c->test();

接口注入

interface sql{

    public function connect();
    public function query();
}


class mysql implements sql {

    public function connect()
    {
        echo '鏈接mysql成功'. "\n";
    }

    public function query()
    {
        // TODO: Implement query() method.
    }
}

class sqlServe implements sql {

    public function connect()
    {
        echo '鏈接sqlServe成功'. "\n";
    }

    public function query()
    {
        // TODO: Implement query() method.
    }
}

class Demo{

    public $sql;

    public function __construct(sql $sql)
    {
        $this->sql = $sql;

    }
}

$mysql = new mysql();
$sqlServe = new sqlServe();

(new Demo($mysql))->sql->connect();