在模板方法模式中,一个抽象类定义模板方法,然后以本身不可覆盖的方法中调用这些模板方法。实现类继承这个抽象类,覆盖原来需要重新定义业务逻辑的模板方法。这个模式属于行为型模式之一,也是比较常用的设计模式之一。
实例实现,定义一个抽象类Game,分别定义其继承类Cricket和Football。UML类图如下所示:
定义游戏类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();
}
}
具体实现类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!");
}
}
具体实现类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!");
}
}
测试类,测试运行结果。
public class TemplatePatternDemo {
public static void main(String[] args) {
Game game = new Cricket();
game.play();
System.out.println();
game = new Football();
game.play();
}
}
运行结果:
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!
是不是觉得这里例子挺简单的,这个模式确实很简单。