PHP设计模式学习

1.抽象类abstract
抽象函数：
abstract public function trick($whatever);
包含至少一个抽象函数的类就是抽象类，它其中也可以包含具体函数：

<?php
 abstract class OneTrickAbstract
 {
     public $storeHere;
     abstract public function trick($whatever);
 }
?>

抽象类的子类必须实现父类的抽象方法：

<?php
include_once('OneTrickAbstract.php');
class OneTrickConcrete extends OneTrickAbstract
{
    public function trick($whatever)
    {
        $this->storeHere="An abstract property";
        return $whatever . $this->storeHere;
    }
}
$worker=new OneTrickConcrete();
echo $worker->trick("From an abstract origin...");

PHP不支持多重继承，但是支持使用Trait以实现同样的功能（没展开讲）。

2.接口interface
接口与抽象类中都包含有抽象函数，但是接口中不能包含变量和具体方法（一般用I开头的标示符）：

<?php
interface IMethodHolder
{
    public function getInfo($info);
    public function sendInfo($info);
    public function calculate($first,$second);
}
?>

接口的实现必须使用implements关键字：

<?php
include_once('IMethodHolder.php');
class ImplementAlpha implements IMethodHolder
{
    public function getInfo($info)
    {
        echo "This is NEWS! " . $info . "<br/>";
    }
    public function sendInfo($info)
    {
        return $info;
    }
    public function calculate($first,$second)
    {
     $calulated = $first * $second;
     return $calulated;
    }
    public function useMethods()
    {
        $this->getInfo("The sky is falling...");
        echo $this->sendInfo("Vote for Senator Snort!") . "<br/>";
        echo "You make $" . $this->calculate(20,15) . " in your part-time 
         job<br/>";
    }
}
$worker=new ImplementAlpha();
$worker->useMethods();
?>

接口中不能有变量，但是可以有常量：

<?php
interface IConnectInfo
{
    const HOST ="localhost";
    const UNAME ="phpWorker";
    const DBNAME = "dpPatt";
    const PW ="easyWay";
    function testConnection();
}
?>

在使用中，双冒号：
$server=IConnectInfo::HOST;
3.类型提示type hinting
看代码：

Interface
//IProduct.php
<?php
interface IProduct
{
    function apples();
    function oranges();
}
?>
FruitStore Implementation
//FruitStore.php
<?php
include_once('IProduct.php');
class FruitStore implements IProduct
{
    public function apples()
    {
        return "FruitStore sez--We have apples. <br/>";
    }
    public function oranges()
    {
        return "FruitStore sez--We have no citrus fruit.<br/>";
    }
}
?>
CitrusStore Implementation
//CitrusStore.php
<?php
include_once('IProduct.php');
class CitrusStore implements IProduct
{
    public function apples()
    {
        return "CitrusStore sez--We do not sell apples. <br/>";
    }
    public function oranges()
    {
        return "CitrusStore sez--We have citrus fruit.<br/>";
    }
}
?>
Object with type hinting
//UseProducts.php
<?php
include_once('FruitStore.php');
include_once('CitrusStore.php');
class UseProducts
{
    public function __construct()
    {
        $appleSauce=new FruitStore();
        $orangeJuice=new CitrusStore();
        $this->doInterface($appleSauce);
        $this->doInterface($orangeJuice);
    }
    //IProduct is type hint in doInterface()
    function doInterface(IProduct $product)
    {
        echo $product->apples();
        echo $product->oranges();
    }
}
$worker=new UseProducts();
?>