Strategy Pattern(策略模式)

  public class Simulator {
      /**
       * @param args
       */
      public static void main(String[] args) {
          // TODO Auto-generated method stub
          Character sprite = new Sprite();//使用多型建立
          Character normalman = new NormalMan();//同上
          Character samuri = new Samuri();//同上
          Character monsterboss = new MonsterBoss();//同上
          //executeAttack 是 Character 類別的方法,方法內容為 ab 呼叫 attack 方法
               //而各 ab 是在每個建構子中建立不同的 ab
          sprite.executeAttack();
          normalman.executeAttack();
          samuri.executeAttack();
          monsterboss.executeAttack();
               //動態改變 ab
          monsterboss.setAttackBehavior(new AttackBySword());
          monsterboss.executeAttack();
          monsterboss.setAttackBehavior(new AttackByMagic());
          monsterboss.executeAttack();
      }
  }

    
  public abstract class Character {
   
      AttackBehavior ab;//(攻擊行為)常變動的部分封裝成類別,宣告為介面型態可以動態改變
      public void executeAttack(){
          ab.attack();
      }
      public void setAttackBehavior(AttackBehavior ab){
          this.ab = ab;
      }
  }
   
  class NormalMan extends Character{
      public NormalMan(){
          ab = new AttackByHand();
      }
  }
   
  class Sprite extends Character{
      public Sprite(){
          ab = new AttackByMagic();
      }
  }
   
  class Samuri extends Character{
      public Samuri(){
          ab = new AttackBySword();
      }
  }
   
  class MonsterBoss extends Character{
      public MonsterBoss(){
          ab = new AttackByHand();
      }
  }

   
  public interface AttackBehavior {
      public void attack();
  }
   
  class AttackByHand implements AttackBehavior{
      public void attack(){
          System.out.println("AttackByHand");
      }
  }
   
  class AttackBySword implements AttackBehavior{
      public void attack(){
          System.out.println("AttackBySword");
      }
  }
   
  class AttackByMagic implements AttackBehavior{
      public void attack(){
          System.out.println("AttackByMagic");
      }
  }