享元模式

/**
 * 享元模式:简单点说就是使用了缓存的方式,用map或list来存已经创建的对象,获取的时候直接从map或者list中获取就行了,获取不到再new出来,然后再存进去;
 * 用到的地方有各种常量池,Short在jdk中-128到127的值是缓存在一个数组中,这里使用一个Map简单模拟下缓存模式
 *
 *
 */
public class ShapeFactory {

    private static Map<String,Shape> map=new HashMap<>();

    public static Shape getShape(String shapeName){
        Shape shape = map.get(shapeName);
        if(null==shape){
            shape = new Shape();
            map.put(shapeName,shape);
        }

        return shape;
    }
}
public class Shape {
    private String name;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }
}
public class Test {
    public static void main(String[] args) {
        Shape circle1 = ShapeFactory.getShape("circle");//获取圆形
        Shape circle2 = ShapeFactory.getShape("circle");//获取圆形
        System.out.println(circle1==circle2);//true

    }
}