设计模式_策略方法

Posted 2021-02-15 tjc1996

模式：行为型模式
在策略模式中，我们常见各种策略对象和一个行为随着策略对象改变而改变的 context 对象。策略对象改变 context 对象执行算法。
策略模式主要是用来封装一组互相替换的算法，可以根据需要动态地替换 Context 使用的算法。

? 代码实现

public interface Strategy{
    public int operation();
}

public class OperationSubstract implements Strategy{
   @Override
   public int doOperation(int num1, int num2) {
      return num1 - num2;
   }
}

public class OperationMultiply implements Strategy{
   @Override
   public int doOperation(int num1, int num2) {
      return num1 * num2;
   }
}

public class Context {
   private Strategy strategy;
 
   public Context(Strategy strategy){
      this.strategy = strategy;
   }
 
   public int executeStrategy(int num1, int num2){
      return strategy.doOperation(num1, num2);
   }
}

public class StrategyPatternDemo {
   public static void main(String[] args) {
      Context context = new Context(new OperationAdd());    
      System.out.println("10 + 5 = " + context.executeStrategy(10, 5));
 
      context = new Context(new OperationSubstract());      
      System.out.println("10 - 5 = " + context.executeStrategy(10, 5));
 
      context = new Context(new OperationMultiply());    
      System.out.println("10 * 5 = " + context.executeStrategy(10, 5));
   }
}