PHP中关键字interface和implements详解

<?php
//简单定义实现接口
interface UserInterface{ //定义user接口
 function getname();
}
interface TeacherInterface{ //定义teacher接口
 function getLengthofService();
}
class User implements UserInterface{ //实现user接口
 private $name="nostop";
 public function getName(){
  return $this->name;
 }
}
class Teacher implements TeacherInterface{ //实现teacher接口
 private $age=23;
 public function getLengthofService(){
  return $this->age;
 }
}
$user=new User();
echo $user->getName().'<br />';//nostop
$teacher=new Teacher();
echo $teacher->getLengthofService().'<br />';//23
//继承类实现接口
class GraduResultudent extends User implements TeacherInterface{ //继承User类 实现接口
 private $teacher;
 public function __construct(){  //定义构造函数
  $this->teacher=new Teacher(); //实例化Teacher对象
 }
 public function getLengthOfService(){ //实现TeacherInterface接口的方法
  return $this->teacher->getLengthOfService();
 }
}

class Result{
 public static function getUserName(UserInterface $_user){ //注意：这里面的类型变成接口类型
  echo "Name is ".$_user->getName().'<br />';
 }
 public static function getLengthOfService(TeacherInterface $_teacher){ //注意：这里面的类型变成接口类型
  echo "age is ".$_teacher->getLengthOfService();
 }
}

$object=new GraduResultudent();
Result::getUserName($object); //Name is nostop
Result::getLengthOfService($object); //age is 23
echo "<br />";
//接口实现用户的折扣
interface People{ //定义接口
 function getUserType();
 function getCount();
}

class VipUser implements People{ //实现接口
 //用户折卡系数
 private $discount=0.8;
 function getUserType(){
  return "VIP用户";
 }
 function getCount(){
  return $this->discount;  
 }
}

$vip=new VipUser(); //实现化对象
echo $vip->getUserType().'商品价格：'.$vip->getCount()*100; //VIP用户商品价格：80

class Goods{
 var $price=100;
 var $member;
 function run(People $member){ //注意：这里面的参数类型是接口类型
  $this->member=$member;
  $discount=$this->member->getCount();
  $usertype=$this->member->getUserType();
  echo $usertype."商品价格：".$this->price*$discount;
 }
}
$display=new Goods();
$display->run(new VipUser);//VIP用户商品价格：80

?>