设计模式 - 模板模式

在模板模式中，抽象类公开定义好的方法/模板来执行其方法。其子类可以根据需要覆盖方法实现，但调用方式必须与抽象类定义的方式相同。此模式属于行为模式类别。

实现

我们将创建一个Game抽象类，定义具有模板方法的操作，并将模板方法设置为final，以便无法覆盖。Cricket和Football是扩展Game并覆盖其方法的具体类。

TemplatePatternDemo，我们的演示类，将使用Game来演示模板模式的使用。

步骤1

创建一个具有最终模板方法的抽象类。

Game.java

public abstract class Game {
   abstract void initialize();
   abstract void startPlay();
   abstract void endPlay();

   //template method
   public final void play(){

      //initialize the game
      initialize();

      //start game
      startPlay();

      //end game
      endPlay();
   }
}

步骤2

创建扩展上述类的具体类。

Cricket.java

public class Cricket extends Game {

   @Override
   void endPlay() {
      System.out.println("Cricket Game Finished!");
   }

   @Override
   void initialize() {
      System.out.println("Cricket Game Initialized! Start playing.");
   }

   @Override
   void startPlay() {
      System.out.println("Cricket Game Started. Enjoy the game!");
   }
}

Football.java

public class Football extends Game {

   @Override
   void endPlay() {
      System.out.println("Football Game Finished!");
   }

   @Override
   void initialize() {
      System.out.println("Football Game Initialized! Start playing.");
   }

   @Override
   void startPlay() {
      System.out.println("Football Game Started. Enjoy the game!");
   }
}

步骤3

使用Game的模板方法play()来演示定义好的游戏玩法。

TemplatePatternDemo.java

public class TemplatePatternDemo {
   public static void main(String[] args) {

      Game game = new Cricket();
      game.play();
      System.out.println();
      game = new Football();
      game.play();		
   }
}

步骤4

验证输出。

Cricket Game Initialized! Start playing.
Cricket Game Started. Enjoy the game!
Cricket Game Finished!

Football Game Initialized! Start playing.
Football Game Started. Enjoy the game!
Football Game Finished!