PHP のインターフェイス、抽象クラス、およびインターフェイスと抽象クラスの違いの詳細な説明

<?php
# 接口
interface Human{
    const TEST_CONST = "test const"; // 定义常量
    // public $v; // error，不能定义变量
    // static $count; // error，不能定义变量
    public function speak();
    public function walk();
    public function run();
}
     
# 抽象类
abstract class Father implements Human{
     
    public function construct(){
        echo "father init n";
    }
     
    abstract public function walk(); // 抽象方法
     
    public function speak(){
        echo "father speak skill n";
    }
     
    public function run(){
        echo "father run skill n";
    }
}
     
# 非抽象类
class Mother implements Human{
     
    public function construct(){
        echo "mother init n";
    }
     
    # 这里必须实现walk方法
    public function walk(){
        echo "mother walk skill n"; 
    } 
     
    public function speak(){
        echo "mother speak skill n";
    }
     
    public function run(){
        echo "mother run skill n";
    }
}
     
class Son extends Father{
     
    public function walk(){
        echo "son walk skill. n";
    }
     
    public function speak($name = &#39;&#39;){
        echo "son: ". $name ." speak skill. n";
    }
     
    # 访问控制必须和父类中一样（或者更为宽松）
    protected function sport(){
        echo "son sport skill. n";
    }
     
    final public function notTeach(){
        echo &#39;son has not to teach skill&#39;;
    }
}
     
class Daughter extends Mother{
     
    public function run($name = &#39;&#39;){
        echo "daughter run skill. n";
    }
     
}
     
final class GrandChild extends Son{
         
    # 访问控制必须和父类中一样（或者更为宽松）
    public function sport(){
        echo "GrandChild sport skill. n";
    }
     
    # Cannot override final method Son::notTeach()
    // public function notTeach(){} // error
}
     
#  Class Orphan may not inherit from final class (GrandChild)
// class Orphan extends GrandChild{}  // error
     
$son = new Son();
$son->speak("Suly");
     
$daughter = new Daughter();
$daughter->run(&#39;Lily&#39;);
     
$grandChild = new GrandChild();
$grandChild->sport();