php使用接口与组合模拟多继承

通过组合模拟多重继承。

在PHP中不支持多重继承，如果我们向使用多个类的方法而实现代码重用有什么办法么?

那就是组合。在一个类中去将另外一个类设置成属性。

下面的例子，模拟了多重继承。

接口实例

写一个概念性的例子。 我们设计一个在线销售系统，用户部分设计如下： 将用户分为，NormalUser, VipUser, InnerUser 三种。要求根据用户的不同折扣计算用户购买产品的价格。并要求为以后扩展和维护预留空间。

代码如下:
interface User
{
public function getName();
public function setName($_name);
public function getDiscount();
}
abstract class AbstractUser implements User
{
private $name = "";
protected $discount = 0;
protected $grade = "";
function __construct($_name) {
$this->setName($_name);
}
function getName() {
return $this->name;
}
function setName($_name) {
$this->name = $_name;
}
function getDiscount() {
return $this->discount;
}
function getGrade() {
return $this->grade;
}
}
class NormalUser extends AbstractUser
{
protected $discount = 1.0;
protected $grade = "Normal";
}
class VipUser extends AbstractUser
{
protected $discount = 0.8;
protected $grade = "VipUser";
}
class InnerUser extends AbstractUser
{
protected $discount = 0.7;
protected $grade = "InnerUser";
}
interface Product
{
function getProductName();
function getProductPrice();
}
interface Book extends Product
{
function getAuthor();
}
class BookOnline implements Book
{
private $productName;
protected $productPrice;
protected $Author;
function __construct($_bookName) {
$this->productName = $_bookName;
}
function getProductName() {
return $this->productName;
}
function getProductPrice() {
$this->productPrice = 100;
return $this->productPrice;
}
public function getAuthor() {
$this->Author = "chenfei";
return $this->Author;
}
}
class Productsettle
{
public static function finalPrice(User $_user, Product $_product, $number) {
$price = $_user->getDiscount() * $_product->getProductPrice() * $number;
return $price;
}
}
$number = 10;
$book = new BookOnline("设计模式");
$user = new NormalUser("tom");
$price = Productsettle::finalPrice($user, $book, $number);
$str = "您好，尊敬的" . $user->getName() . "
";
$str .= "您的级别是" . $user->getGrade() . "
";
$str .= "您的折扣是" . $user->getDiscount() . "
";
$str .= "您的价格是" . $price;
echo $str;
?>