软件设计模式(Design pattern),又称设计模式,是一套被反复使用、多数人知晓的、经过分类编目的、代码设计经验的总结。使用设计模式是为了可重用代码、让代码更容易被他人理解、保证代码可靠性、程序的重用性。
汇总目录链接:【玩转23种Java设计模式】学习目录汇总整理
将一个对象作为原型,通过对其进行复制而克隆出多个和原型类似的新实例。 这种模式是实现了一个原型接口,该接口用于创建当前对象的克隆。当直接创建对象的代价比较大时,则采用这种模式。
实现了Cloneable接口的抽象类。
public abstract class Shape implements Cloneable {
private String id;
protected String type;
abstract void buy();
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 Apple extends Shape {
public Apple(){
type = "Apple";
}
@Override
public void buy() {
System.out.println("buy() method: Apple");
}
}
public class Banana extends Shape {
public Banana(){
type = "Banana";
}
@Override
public void buy() {
System.out.println("buy() method: Banana");
}
}
public class Orange extends Shape {
public Orange(){
type = "Orange";
}
@Override
public void buy() {
System.out.println("buy() method: Orange");
}
}
public class ShapeCache {
private static HashMap<String, Shape> shapeMap = new HashMap<String, Shape>();
public static Shape getShape(String shapeId) {
Shape cachedShape = shapeMap.get(shapeId);
return (Shape) cachedShape.clone();
}
// 对每种水果都运行数据库查询,并创建该水果。shapeMap.put(shapeKey, shape);
public static void loadCache() {
Apple apple = new Apple();
apple.setId("1");
shapeMap.put(apple.getId(),apple);
Banana banana = new Banana();
banana.setId("2");
shapeMap.put(banana.getId(),banana);
Orange orange = new Orange();
orange.setId("3");
shapeMap.put(orange.getId(),orange);
}
}
public class Main {
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());
}
}
控制台输出:
Shape : Apple
Shape : Banana
Shape : Orange