ShapeFactory 有一个 Circle 的 HashMap,其中键名为 Circle 对象的颜色。无论何时接收到请求,都会创建一个特定颜色的圆。ShapeFactory 检查它的 HashMap 中的 circle 对象,如果找到 Circle 对象,则返回该对象,否则将创建一个存储在 hashmap 中以备后续使用的新对象,并把该对象返回到客户端。
FlyWeightPatternDemo,我们的演示类使用 ShapeFactory 来获取 Shape 对象。它将向 ShapeFactory 传递信息(red / green / blue/ black / white),以便获取它所需对象的颜色。
步骤 1
创建一个接口。
Shape.java
public interface Shape {
void draw ( ) ;
}
步骤 2
创建实现接口的实体类。
Circle.java
public class Circle implements Shape {
private String color ;
private int x ;
private int y ;
private int radius ;
public Circle ( String color ) {
this . color = color ;
}
public void setX ( int x ) {
this . x = x ;
}
public void setY ( int y ) {
this . y = y ;
}
public void setRadius ( int radius ) {
this . radius = radius ;
}
@ Override
public void draw ( ) {
System . out . println ( " Circle: Draw() [Color : " + color
+ " , x : " + x + " , y : " + y + " , radius : " + radius ) ;
}
}
步骤 3
创建一个工厂,生成基于给定信息的实体类的对象。
ShapeFactory.java
import java . util . HashMap ;
public class ShapeFactory {
private static final HashMap < String , Shape > circleMap = new HashMap <> ( ) ;
public static Shape getCircle ( String color ) {
Circle circle = ( Circle ) circleMap . get ( color ) ;
if ( circle == null ) {
circle = new Circle ( color ) ;
circleMap . put ( color , circle ) ;
System . out . println ( " Creating circle of color : " + color ) ;
}
return circle ;
}
}
步骤 4
使用该工厂,通过传递颜色信息来获取实体类的对象。
FlyweightPatternDemo.java
public class FlyweightPatternDemo {
private static final String colors [ ] =
{ " Red " , " Green " , " Blue " , " White " , " Black " } ;
public static void main ( String [ ] args ) {
for ( int i = 0 ; i < 20 ; ++ i ) {
Circle circle =
( Circle ) ShapeFactory . getCircle ( getRandomColor ( ) ) ;
circle . setX ( getRandomX ( ) ) ;
circle . setY ( getRandomY ( ) ) ;
circle . setRadius ( 100 ) ;
circle . draw ( ) ;
}
}
private static String getRandomColor ( ) {
return colors [ ( int ) ( Math . random ( ) * colors . length ) ] ;
}
private static int getRandomX ( ) {
return ( int ) ( Math . random ( ) * 100 ) ;
}
private static int getRandomY ( ) {
return ( int ) ( Math . random ( ) * 100 ) ;
}
}
步骤 5
执行程序,输出结果:
Creating circle of color : Black
Circle: Draw() [Color : Black, x : 36, y :71, radius :100
Creating circle of color : Green
Circle: Draw() [Color : Green, x : 27, y :27, radius :100
Creating circle of color : White
Circle: Draw() [Color : White, x : 64, y :10, radius :100
Creating circle of color : Red
Circle: Draw() [Color : Red, x : 15, y :44, radius :100
Circle: Draw() [Color : Green, x : 19, y :10, radius :100
Circle: Draw() [Color : Green, x : 94, y :32, radius :100
Circle: Draw() [Color : White, x : 69, y :98, radius :100
Creating circle of color : Blue
Circle: Draw() [Color : Blue, x : 13, y :4, radius :100
Circle: Draw() [Color : Green, x : 21, y :21, radius :100
Circle: Draw() [Color : Blue, x : 55, y :86, radius :100
Circle: Draw() [Color : White, x : 90, y :70, radius :100
Circle: Draw() [Color : Green, x : 78, y :3, radius :100
Circle: Draw() [Color : Green, x : 64, y :89, radius :100
Circle: Draw() [Color : Blue, x : 3, y :91, radius :100
Circle: Draw() [Color : Blue, x : 62, y :82, radius :100
Circle: Draw() [Color : Green, x : 97, y :61, radius :100
Circle: Draw() [Color : Green, x : 86, y :12, radius :100
Circle: Draw() [Color : Green, x : 38, y :93, radius :100
Circle: Draw() [Color : Red, x : 76, y :82, radius :100
Circle: Draw() [Color : Blue, x : 95, y :82, radius :100