策略模式

一个类的行为或其算法可以在运行期更改。众多算法相似的时候，使用if else引发过于复杂难以维护。

策略接口：

1 public interface Strategy {
2 
3     int operation(int a, int b);
4 }

不同的策略：

 1 public class OperationAdd implements Strategy {
 2 
 3     @Override
 4     public int operation(int a, int b) {
 5         return a + b;
 6     }
 7 }
 8 
 9 public class OperationSub implements Strategy {
10 
11     @Override
12     public int operation(int a, int b) {
13         return a - b;
14     }
15 }

持有策略的上下文：

 1 public class Context {
 2 
 3     private Strategy strategy;
 4 
 5     public Context(Strategy strategy) {
 6         this.strategy = strategy;
 7     }
 8 
 9     public int executeStrategy(int a, int b) {
10         return strategy.operation(a, b);
11     }
12 }

测试类：

 1 public class Main {
 2 
 3     public static void main(String[] args) {
 4         Context context = new Context(new OperationAdd());
 5         System.out.println(context.executeStrategy(1, 2));
 6 
 7         context = new Context(new OperationSub());
 8         System.out.println(context.executeStrategy(5, 3));
 9     }
10 }

 

posted @ 2019-03-13 11:19  Over_Watch  阅读(114)  评论(0)  编辑  收藏  举报