设计模式-原型模式（克隆、Clone、Prototype）

原型模式（克隆、Clone、Prototype）是一种创建型设计模式，使你能够复制已有对象，而又无需使代码依赖它们所属的类。

问题

譬如美国研制了一种特效药，而且还在专利保护器内，而印度制药公司看中了，并且开始模仿，如果他不研究药里面的成分，只是照着药片的样子颜色复制出来肯定不可以，而且他还需要研究药里面每一份的组成和计量比率。这样的你就把药里面的每一个元素一个一个的分析和验证了一遍。就像我们开发中你必须新建一个属于相同类的对象。然后，你必须遍历原始对象的所有成员变量，并将成员变量值复制到新对象中。

原型模式结构

上代码：

public abstract class Shape {public int x;public int y;public String color;public Shape() {}public Shape(Shape target) {if (target != null) {this.x = target.x;this.y = target.y;this.color = target.color;}}public abstract Shape clone();@Overridepublic boolean equals(Object object2) {if (!(object2 instanceof Shape)) return false;Shape shape2 = (Shape) object2;return shape2.x == x && shape2.y == y && Objects.equals(shape2.color, color);}
}

public class Circle extends Shape {public int radius;public Circle() {}public Circle(Circle target) {super(target);if (target != null) {this.radius = target.radius;}}@Overridepublic Shape clone() {return new Circle(this);}@Overridepublic boolean equals(Object object2) {if (!(object2 instanceof Circle) || !super.equals(object2)) return false;Circle shape2 = (Circle) object2;return shape2.radius == radius;}
}

public class Rectangle extends Shape {public int width;public int height;public Rectangle() {}public Rectangle(Rectangle target) {super(target);if (target != null) {this.width = target.width;this.height = target.height;}}@Overridepublic Shape clone() {return new Rectangle(this);}@Overridepublic boolean equals(Object object2) {if (!(object2 instanceof Rectangle) || !super.equals(object2)) return false;Rectangle shape2 = (Rectangle) object2;return shape2.width == width && shape2.height == height;}
}

测试

public class Demo {public static void main(String[] args) {List<Shape> shapes = new ArrayList<>();List<Shape> shapesCopy = new ArrayList<>();Circle circle = new Circle();circle.x = 10;circle.y = 20;circle.radius = 15;circle.color = "red";shapes.add(circle);Circle anotherCircle = (Circle) circle.clone();shapes.add(anotherCircle);Rectangle rectangle = new Rectangle();rectangle.width = 10;rectangle.height = 20;rectangle.color = "blue";shapes.add(rectangle);cloneAndCompare(shapes, shapesCopy);}private static void cloneAndCompare(List<Shape> shapes, List<Shape> shapesCopy) {for (Shape shape : shapes) {shapesCopy.add(shape.clone());}for (int i = 0; i < shapes.size(); i++) {if (shapes.get(i) != shapesCopy.get(i)) {System.out.println(i + ": Shapes are different objects (yay!)");if (shapes.get(i).equals(shapesCopy.get(i))) {System.out.println(i + ": And they are identical (yay!)");} else {System.out.println(i + ": But they are not identical (booo!)");}} else {System.out.println(i + ": Shape objects are the same (booo!)");}}}
}

0: Shapes are different objects (yay!)
0: And they are identical (yay!)
1: Shapes are different objects (yay!)
1: And they are identical (yay!)
2: Shapes are different objects (yay!)
2: And they are identical (yay!)

原型模式优缺点