装饰设计模式1

/**
 * 装饰设计模式
 * 为一个对象动态的添加一些功能
 * 原类和装饰类共同实现一个接口，装饰类持有类的对象，
 * 并在实现接口方法时调用该对象对该接口的实现方法，同时添加新的功能
 */
public class Decorator implements Sourceable {

    private User user;

    public Decorator(User user){
        super();
        this.user = user;
    }

    @Override
    public void method() {
        System.out.println("This will run before method.");
        user.method();
        System.out.println("This will run after method.");
    }
}

public interface Sourceable {
    void method();
}

public class User implements Sourceable {
    @Override
    public void method() {
        System.out.println("The method() in User.");
    }
}

public class Test {
    public static void main(String[] args) {
        User user = new User();
        Sourceable decorator = new Decorator(user);
        decorator.method();
    }
}