装饰模式就是给一个对象增加一些新的功能,而且是动态的,要求装饰对象和被装饰对象实现同一个接口,装饰对象持有被装饰对象的实例
package Decorator;
public interface Sourceable {
public void method();
}
package Decorator;
public class Source implements Sourceable {
@Override
public void method() {
System.out.println("This is Oringal method");
}
}
package Decorator;
public class Decorator implements Sourceable{
private Sourceable source;
public Decorator(Sourceable source){
super();
this.source = source;
}
@Override
public void method() {
System.out.println("before decorator");
source.method();
System.out.println("after decorator");
}
}
package Decorator;
public class DecoratorTest {
public static void main(String[] args) {
Sourceable source = new Source();
Sourceable sourceable = new Decorator(source);
sourceable.method();
}
}
结果:
before decorator
This is Oringal method
after decorator
装饰器模式的应用场景:
1、需要扩展一个类的功能。
2、动态的为一个对象增加功能,而且还能动态撤销。(继承不能做到这一点,继承的功能是静态的,不能动态增删。)