设计模式之生成实例_Prototype复制模式_通过复制生成实例

柔光的暖阳◎ 2024-04-17 05:45 39阅读 0赞

## 前言 ##

#### [博主github][github] ####

#### [博主个人博客http://blog.healerjean.com][http_blog.healerjean.com] ####

## 1、业务场景 ##

\*\*当创建对象的代价比较大的时候，采用这种模式, \*\*

#### 实现方式、 容器,clone ####

## 2、实例代码1 ##

### 2.1、被复制的抽象对象 ###

@Data
    @ToString
    public abstract class Shape implements Cloneable { 
    
        public  String id;
        public  String type;
    
        abstract void draw();
    
        @Override
        public Object clone() { 
            Object clone = null;
            try { 
                clone = super.clone();
            } catch (CloneNotSupportedException e) { 
                e.printStackTrace();
            }
            return clone;
        }
    }

### 2.2、子类 ###

#### 2.2.1、`Rectangle` extends Shape ####

@Data
    @ToString
    public class Rectangle extends Shape { 
    
        private String pectangleName ;
    
        public Rectangle(){ 
            type = "Rectangle";
        }
    
        @Override
        public void draw() { 
            System.out.println(id+":"+type+":"+pectangleName);
        }
    }

#### 2.2.2、`Square` extends Shape ####

@Data
    @ToString
    public class Square extends Shape { 
    
        private String squareName ;
    
        public Square(){ 
            type = "Square";
        }
    
        @Override
        public void draw() { 
            System.out.println(id+":"+type+":"+squareName);
        }
    }

### 2.3、创建和复制的类`ShapeCache` ###

public class ShapeCache { 
    
        private static Map<String, Shape> shapeMap   = new HashMap<>();
    
        /** * 通过map和拷贝 获取全新对象 */
        public static Shape getByType(String shapeId) { 
            Shape cachedShape = shapeMap.get(shapeId);
            return (Shape) cachedShape.clone();
        }
    
        /** * 创建原型 */
        public static void create(Shape shape) { 
            shapeMap.put(shape.getType(),shape);
        }
    }

### 2.4、测试 ###

public class Main { 
    
            public static void main(String[] args) { 
    
                Rectangle rectangle = new Rectangle();
                rectangle.setType("rectangle");
                rectangle.setId("1");
                rectangle.setPectangleName("rectangleName");
                ShapeCache.create(rectangle);
                Square square = new Square();
                square.setType("square");
                square.setId("2");
                square.setSquareName("squareName");
                ShapeCache.create(square);
    
                rectangle = (Rectangle)ShapeCache.getByType("rectangle") ;
                rectangle.draw();
                square =    (Square)ShapeCache.getByType("square") ;
                square.draw();
    
            }
        
        
                // 1:rectangle:rectangleName
                // 2:square:squareName
    }

## 3、总结： ##

`ShapeCache`用于创建和克隆 clone 复制实例对象

![ContactAuthor][]

[github]: https://github.com/HealerJean
[http_blog.healerjean.com]: http://HealerJean.github.io
[ContactAuthor]: https://image.dandelioncloud.cn/pgy_files/images/2024/04/11/4bd807f80e7a48dfbbfd095ef6a06de1.png