java设计模式 --模板方法

1.什么是模板方法？

模板方法模型是一种行为设计模型。模板方法是一个定义在父类的方法，在模板方法中会调用多个定义在父类别的其他方法，而这些方法有可能只是抽象方法并没有实现，模板方法仅决定这些抽象方法的执行顺序，这些抽象方法的实作由子类别负责，并且子类不允许覆写模板方法。

2.举例

/**
  * An abstract class that is common to several games in
  * which players play against the others, but only one is
  * playing at a given time.
  */
 
 abstract class Game {
 
     private int playersCount;
 
     abstract void initializeGame();
 
     abstract void makePlay(int player);
 
     abstract boolean endOfGame();
 
     abstract void printWinner();
 
     /* A template method : */
     final void playOneGame(int playersCount) {
         this.playersCount = playersCount;
         initializeGame();
         int j = 0;
         while (!endOfGame()){
             makePlay(j);
             j = (j + 1) % playersCount;
         }
         printWinner();
     }
 }

//Now we can extend this class in order to implement actual games:

 class Monopoly extends Game {
 
     /* Implementation of necessary concrete methods */
 
     void initializeGame() {
         // ...
     }
 
     void makePlay(int player) {
         // ...
     }
 
     boolean endOfGame() {
         // ...
     }
 
     void printWinner() {
         // ...
     }
  
     /* Specific declarations for the Monopoly game. */
 
     // ...
 
 }

 class Chess extends Game {
 
     /* Implementation of necessary concrete methods */
 
     void initializeGame() {
         // ...
     }
 
     void makePlay(int player) {
         // ...
     }
 
     boolean endOfGame() {
         // ...
     }
 
     void printWinner() {
         // ...
     }
  
     /* Specific declarations for the chess game. */
 
     // ...
 
 }

 public class Player {
     public static void main(String[] args) {
         Game chessGame = new Chess();
         chessGame.initializeGame();
         chessGame.playOneGame(1); //call template method
     }
 }