一个对象的状态依赖于它的内部状态,且在不同的状态下对象有着不同的行为。
UML架构图如下:
实现状态转化常用有两种方式,统一由环境类负责切换状态;以及由具体状态类负责状态转化。本示例使用前者。
package com.kkk.pattern.state; /** * 游戏角色,充当环境类Context. * Created by z3jjlzt on 2018/2/25. */ public class Player { //持有所有状态 private Blood currentBlood, dead, lowBlood, normalBlood, highBlood; //生命值,状态受到生命值影响. private int hp = 600; public Player() { dead = new Dead(); lowBlood = new LowBlood(); normalBlood = new NormalBlood(); highBlood = new HighBlood(); currentBlood = normalBlood; } public void heal(int blood) { if (hp <= 0) { System.out.printf("已经阵亡,无法治疗!!"); } hp += blood; checkState(); } public void hurt(int blood) { if (hp <= 0) { System.out.printf("已经阵亡,无法选中!"); } hp = hp - blood >= 0 ? hp - blood : 0; checkState(); } private void checkState() { if (hp <= 0) { currentBlood = dead; } else if (hp <= 100) { currentBlood = lowBlood; } else if (hp < 600) { currentBlood = normalBlood; } else { currentBlood = highBlood; } currentBlood.report(); System.out.println(hp); } } /** * Created by z3jjlzt on 2018/2/25. */ public class Dead extends Blood { @Override void report() { System.out.println("GG!!!"); } } /** * Created by z3jjlzt on 2018/2/25. */ public abstract class Blood { abstract void report(); } /** * Created by z3jjlzt on 2018/2/25. */ public class LowBlood extends Blood{ @Override void report() { System.out.println("血线过低,无法参加战斗!!"); } } /** * Created by z3jjlzt on 2018/2/25. */ public class NormalBlood extends Blood{ @Override void report() { System.out.println("血线健康,可以参加战斗!!"); } } /** * Created by z3jjlzt on 2018/2/25. */ public class HighBlood extends Blood { @Override void report() { System.out.println("战斗力爆棚,请求1v5!!!"); } } /** * Created by z3jjlzt on 2018/2/25. */ public class Client { public static void main(String[] args) { Player player = new Player(); player.hurt(300); player.hurt(201); player.heal(200); player.heal(200); player.hurt(1200); } } 输出结果: 血线健康,可以参加战斗!! 300 血线过低,无法参加战斗!! 99 血线健康,可以参加战斗!! 299 血线健康,可以参加战斗!! 499 GG!!! 0