策略模式

定义

策略模式（Strategy），它定义了算法家族，分别封装起来，让他们之间可以相互替换，此模式让算法得变化，不会影响到使用算法得用户。

 代码实现如下：

public abstract class Strategy {
    //算法方法
    public abstract void algorithInterface();
}

public class ConcreteStrategyA extends Strategy {

    @Override
    public void algorithInterface() {
        System.out.println("A实现");

    }

}

public class ConcreteStrategyB extends Strategy {

    @Override
    public void algorithInterface() {
        System.out.println("B实现");
        
    }

}

public class ConcreteStrategyC extends Strategy {

    @Override
    public void algorithInterface() {
        System.out.println("C实现");
    }

}

public class Context {
    Strategy strategy;

    public Context(Strategy strategy) {
        this.strategy = strategy;
    }
    
    public void contextInterface(){
        strategy.algorithInterface();
    }
}

public class TestStrategy {
    public static void main(String[] args) {
        Context context;
        context = new Context(new ConcreteStrategyA());
        context.contextInterface();
        context = new Context(new ConcreteStrategyB());
        context.contextInterface();
        context = new Context(new ConcreteStrategyC());
        context.contextInterface();
    }
}

A实现
B实现
C实现