package com.interview.design.pattern.creational;
import java.util.Hashtable;
/**
* Created_By: stefanie
* Date: 14-12-2
* Time: 下午10:55
*
* This pattern involves implementing a prototype interface which tells to create a clone of the current object.
* This pattern is used when creation of object directly is costly.
* For example, a object is to be created after a costly database operation. We can cache the object,
* returns its clone on next request and update the database as as and when needed thus reducing database calls.
*/
public class PrototypePattern {
/**
* A prototype class Shape which implements Cloneable
*/
static 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;
}
}
/**
* Three sub-class of Shape
*/
static class Rectangle extends Shape {
public Rectangle(){
type = "Rectangle";
}
@Override
public void draw() {
System.out.println("Inside Rectangle::draw() method.");
}
}
static class Square extends Shape {
public Square(){
type = "Square";
}
@Override
public void draw() {
System.out.println("Inside Square::draw() method.");
}
}
static class Circle extends Shape {
public Circle(){
type = "Circle";
}
@Override
public void draw() {
System.out.println("Inside Circle::draw() method.");
}
}
/**
* The abstract factory to create Shape using clone
*/
static 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();
}
// assume for each shape run database query and create shape
// shapeMap.put(shapeKey, shape);
// for example, we are adding three shapes
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 static void main(String[] args) {
ShapeCache.loadCache();
Shape clonedShape = ShapeCache.getShape("1");
System.out.println("Shape : " + clonedShape.getType());
Shape clonedShape2 = ShapeCache.getShape("2");
System.out.println("Shape : " + clonedShape2.getType());
Shape clonedShape3 = ShapeCache.getShape("3");
System.out.println("Shape : " + clonedShape3.getType());
}
}