设计模式-策略模式

public class 策略模式 {
    public static void main(String[] args)
    {
        Strategy add=new ConcreteStrategyA();
        Strategy sub=new ConcreteStrategyB();
        Strategy multiply=new ConcreteStrategyC();
        OperationContext context=new OperationContext(add);
        context.Operation(4,5);
        context=new OperationContext(sub);
        context.Operation(4,5);
        context=new OperationContext(multiply);
        context.Operation(4,5);
    }
}
class OperationContext{
    Strategy strategy;
    public OperationContext(Strategy strategy)
    {
        this.strategy=strategy;
    }
    public void Operation(int a,int b){
        strategy.TwoNumberOperation(a,b);
    }
}
interface Strategy{
    public void TwoNumberOperation(int a,int b);
}
class ConcreteStrategyA implements Strategy{
    @Override
    public void TwoNumberOperation(int a,int b)
    {
        System.out.println(a+b);
    }
}
class ConcreteStrategyB implements Strategy{
    @Override
    public void TwoNumberOperation(int a,int b)
    {
        System.out.println(a-b);
    }
}
class ConcreteStrategyC implements Strategy{
    @Override
    public void TwoNumberOperation(int a,int b)
    {
        System.out.println(a*b);
    }
}