java generator

很多朋友都想知道java generator是什么？下面就一起來了解一下吧~

java generator就是將泛型應用于接口，接口必須有返回類型為泛型T的next()方法，是一種專門負責創建對象的類。在很多設計模式都會用到（比如工廠方法模式），類似于Iterable對象中使用使用next()不斷獲得下一個值，這里泛型接口中的next()方法返回創建對象。

2、實現一個CommonGenerator通用生成器

實現一個通用生成器，通過next不斷返回一個對象的實例

interface Generator

1?/**2??*?Generator泛型接口?
3??*?@author?Jian4??*?@param?5??*/6?public?interface?Generator?{7?????T?next();8?}

CommonGenerator：

1?/**?2??*?CommonGenerator繼承Generator泛型接口，實現通過next不斷返回實例?3??*?@author?Jian?4??*?@param??5??*/?6?public?class?CommonGenerator?implements?Generator{?7?????private?Class?type;?8?????/**?9??????*?CommonGenerator?Constructor10??????*?@param?type11??????*/12?????public??CommonGenerator(Class?type)?{13?????????this.type?=?type;14?????}15?????/**16??????*?next()不斷返回xxx.class的對象17??????*/18?????@Override19?????public?T?next()?{20?????????try?{21?????????????//傳入class返回對象22?????????????return?type.newInstance();23?????????}?catch?(Exception?e)?{24?????????????throw?new?RuntimeException(e);25?????????}26?????}27?????/**28??????*?@param?type?傳入創建類xxx.class29??????*?@return?CommonGenerator實例30??????*/31?????public?static??Generator?create(Class?type){32?????????return?new?CommonGenerator(type);33?????}34?}

TestObject：
1?/**?2??*?測試類：統計返回測試類的引用實例的數目?3??*?@author?Jian?4??*?5??*/?6?public?class?TestObject?{?7?????private?static?long?counter=?0;//統計計數器?8?????public?String?toString()?{?9?????????//注意:這里return中不能用this，否則會出現遞歸10?????????return?"TestObject?"?+?(counter++);11?????}12?}

MainClass：

1?public?class?MainClass?{2?????public?static?void?main(String[]?args)?{3?????????Generator?generator?=?new?CommonGenerator<>(TestObject.class);4?????????for(int?i=0;i<3;i++)?{5?????????????//generator.next()返回對象，輸出調用toString方法6?????????????System.out.println(generator.next());7?????????}8?????}9?}

輸出：

TestObject?0TestObject?1TestObject?2

以上就是小編今天的分享希望可以幫到大家。