装饰模式

２、Decorator ^{_{(recognizeable by creational methods taking an instance of same abstract/interface type which adds additional behaviour)}}

^{_{--装饰模式（为一个对象动态的加上一系列的动作，而不需要因为这些动作的不同而产生大量的继承类）}}

例如：

public BufferedInputStream(InputStream in, int size) {
        super(in);
        if (size <= 0) {
            throw new IllegalArgumentException("Buffer size <= 0");
        }
        buf = new byte[size];
    }