牛仔褲的夏天

我對(duì)decorate模式的理解：
1-首先要有一個(gè)Interface，提供一個(gè)通用的方法；
2-其次有n多個(gè)class來實(shí)現(xiàn)這個(gè)接口中的方法，這些實(shí)現(xiàn)方法在功能上應(yīng)該是并列的，但不是必須的，從而可以根據(jù)需要decorate那個(gè)需要被修飾的初始對(duì)象。
3-最后這些class都有一個(gè)帶有Interface作為參數(shù)的構(gòu)造方法和一個(gè)Interface的屬性，這樣在構(gòu)造的時(shí)候就可以取得那個(gè)需要修飾的對(duì)象的實(shí)例，然后在實(shí)現(xiàn)Interface的方法里面，首先實(shí)現(xiàn)修飾對(duì)象實(shí)例的修飾方法，然后再進(jìn)行自己的decorate方法。

根據(jù)這個(gè)想法來畫一張畫：

package ?test;

public ? interface ?Painting? {
???? public ? void ?paint();
}

class ?SunPainting? implements ?Painting? {
????Painting?painting? = ? null ;

???? public ?SunPainting()? {
????}

???? public ?SunPainting(Painting?painting)? {
???????? this .painting? = ?painting;
????}

???? public ? void ?paint()? {
???????? if ?(painting? != ? null )? {
????????????painting.paint();
????????}
????????System.out.println( " 畫了一個(gè)太陽 " );
????}
}

class ?CloudPainting? implements ?Painting? {
????Painting?painting? = ? null ;

???? public ?CloudPainting()? {
????}

???? public ?CloudPainting(Painting?painting)? {
???????? this .painting? = ?painting;
????}

???? public ? void ?paint()? {
???????? if ?(painting? != ? null )? {
????????????painting.paint();
????????}
????????System.out.println( " 畫了一朵白云 " );
????}
}

class ?LawnPainting? implements ?Painting? {
????Painting?painting? = ? null ;

???? public ?LawnPainting()? {
????}

???? public ?LawnPainting(Painting?painting)? {
???????? this .painting? = ?painting;
????}

???? public ? void ?paint()? {
???????? if ?(painting? != ? null )? {
????????????painting.paint();
????????}
????????System.out.println( " 畫了一片草地 " );
????}
}

再寫段測(cè)試畫畫的代碼:

package ?test;

public ? class ?TestPainting? {
???? public ? static ? void ?main(String[]?args) {
???????? new ?SunPainting( new ?CloudPainting( new ?LawnPainting())).paint();
????}
}

測(cè)試結(jié)果:

畫了一片草地
畫了一朵白云
畫了一個(gè)太陽

?最后有個(gè)問題：為什么不直接定義一個(gè)畫畫的類，然后把這些該怎么畫的事情分別通過方法來實(shí)現(xiàn)呢？ 那么什么情況下使用decorate模式更為合適呢？