Strategy Pattern(策略模式)

   1:   

   2:  public class Simulator {

   3:   

   4:      /**

   5:       * @param args

   6:       */

   7:      public static void main(String[] args) {

   8:          // TODO Auto-generated method stub

   9:          

  10:          Character sprite = new Sprite();//使用多型建立

  11:          Character normalman = new NormalMan();//同上

  12:          Character samuri = new Samuri();//同上

  13:          Character monsterboss = new MonsterBoss();//同上

  14:          //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

  15:          sprite.executeAttack();

  16:          normalman.executeAttack();

  17:          samuri.executeAttack();

  18:          

  19:          monsterboss.executeAttack();

               //動態改變 ab

  20:          monsterboss.setAttackBehavior(new AttackBySword());

  21:          monsterboss.executeAttack();

  22:          monsterboss.setAttackBehavior(new AttackByMagic());

  23:          monsterboss.executeAttack();

  24:      }

  25:   

  26:  }

   1:   

   2:  public abstract class Character {

   3:   

   4:      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

   5:      

   6:      public void executeAttack(){

   7:          ab.attack();

   8:      }

   9:      

  10:      public void setAttackBehavior(AttackBehavior ab){

  11:          this.ab = ab; 

  12:      }

  13:  }

  14:   

  15:  class NormalMan extends Character{

  16:      

  17:      public NormalMan(){

  18:          ab = new AttackByHand();

  19:      }

  20:  }

  21:   

  22:  class Sprite extends Character{

  23:      

  24:      public Sprite(){

  25:          ab = new AttackByMagic();

  26:      }

  27:  }

  28:   

  29:  class Samuri extends Character{

  30:      

  31:      public Samuri(){

  32:          ab = new AttackBySword();

  33:      }

  34:  }

  35:   

  36:  class MonsterBoss extends Character{

  37:      public MonsterBoss(){

  38:          ab = new AttackByHand();

  39:      }

  40:  }

   1:   

   2:  public interface AttackBehavior {

   3:      

   4:      public void attack();

   5:  }

   6:   

   7:  class AttackByHand implements AttackBehavior{

   8:      

   9:      public void attack(){

  10:          System.out.println("AttackByHand");

  11:      }

  12:  }

  13:   

  14:  class AttackBySword implements AttackBehavior{

  15:      

  16:      public void attack(){

  17:          System.out.println("AttackBySword");

  18:      }

  19:  }

  20:   

  21:  class AttackByMagic implements AttackBehavior{

  22:      

  23:      public void attack(){

  24:          System.out.println("AttackByMagic");

  25:      }

  26:  }

   1:  AttackByMagic

   2:  AttackByHand

   3:  AttackBySword

   4:  AttackByHand

   5:  AttackBySword

   6:  AttackByMagic