Java实现(05)——原型模式(Prototype Pattern)

原型模式通过给出一个原型对象来指明所创建的对象的类型，然后用复制这个原型对象的办法创建出更多同类型的对象。



public abstract class Shape implements Cloneable {
private String id;
protected String type;
abstract void draw();
public String getType() {
return type;
}
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
public Object clone() {
Object clone = null;
try {
clone = super.clone();
} catch (CloneNotSupportedException e) {
e.printStackTrace();
}
return clone;
}
}

public class Rectangle extends Shape {

public Rectangle() {
type = "Rectangle";
}
@Override
void draw() {
System.out.println("Inside Rectangle::draw() method.");
}
}

public class Square extends Shape {
public Square() {
type = "Square";
}

@Override
void draw() {
System.out.println("Inside Square::draw() method.");
}
}

public class Circle extends Shape {
public Circle() {
type = "Circle";
}
@Override
void draw() {
System.out.println("Inside Circle::draw() method.");
}
}

import java.util.Hashtable;

/**
* Created by wang on 16-12-6.
*/
public class ShapeCache {
private static Hashtable<String, Shape> shapeMap = new  Hashtable<String, Shape>();
public static Shape getShape(String shapeId) {
Shape cachedShape = shapeMap.get(shapeId);
return (Shape) cachedShape.clone();
}
public static void loadCache() {
Circle circle = new Circle();
circle.setId("1");
shapeMap.put(circle.getId(), circle);

Square square = new Square();
square.setId("2");
shapeMap.put(square.getId(), square);

Rectangle rectangle = new Rectangle();
rectangle.setId("3");
shapeMap.put(rectangle.getId(), rectangle);
}
}

public class Demo {
public static void main(String[] args) {
ShapeCache.loadCache();
Shape clonedShape = (Shape) ShapeCache.getShape("1");
System.out.println("Shape: " + clonedShape.getType());
Shape clonedShape2 = (Shape) ShapeCache.getShape("2");
System.out.println("Shape: " + clonedShape2.getType());
Shape clonedShape3 = (Shape) ShapeCache.getShape("3");
System.out.println("Shape: " + clonedShape3.getType());
}
}

输出：
Shape: Circle

Shape: Square

Shape: Rectangle