/**
 * 这样做有一个致命的缺点，一旦出行的方式要增加，
 * 我们就不得不增加新的else if语句，而这违反了面向对象的原则之一，
 * 对修改封闭。而这时候，策略模式则可以完美的解决这一切。
 */
public static void testNormol() {TravelStrategy walk=new TravelStrategy(TravelStrategy.Strategy.WALK);
    walk.travel();

    TravelStrategy plane=new TravelStrategy(TravelStrategy.Strategy.PLANE);
    plane.travel();

    TravelStrategy subway=new TravelStrategy(TravelStrategy.Strategy.SUBWAY);
    subway.travel();
}

public class TravelStrategy {enum Strategy{WALK,PLANE,SUBWAY
    }private Strategy strategy;
    public TravelStrategy(Strategy strategy){this.strategy=strategy;
    }public void travel(){if(strategy==Strategy.WALK){print("walk");
        }else if(strategy==Strategy.PLANE){print("plane");
        }else if(strategy==Strategy.SUBWAY){print("subway");
        }}public void print(String str){System.out.println("出行旅游的方式为："+str);
    }}

/**
 * 可以看到，应用了策略模式后，如果我们想增加新的出行方式，
 * 完全不必要修改现有的类，我们只需要实现策略接口即可，
 * 这就是面向对象中的对扩展开放准则。
 * 假设现在我们增加了一种自行车出行的方式。只需新增一个类即可。
 */
public static void testStrategy(){TravelContext travelContext=new TravelContext();
    travelContext.setStrategy(new PlaneStrategy());
    travelContext.travel();
    travelContext.setStrategy(new WalkStrategy());
    travelContext.travel();
    travelContext.setStrategy(new SubwayStrategy());
    travelContext.travel();
}

/**
 * Created by Administrator on 2017/9/15.
 */

public interface Strategy {void travel();

}

/**
 * Created by Administrator on 2017/9/15.
 */

public class PlaneStrategy implements Strategy {@Override
    public void travel() {Log.d("PlaneStrategy","travel");
    }
}

/**
 * Created by Administrator on 2017/9/15.
 */

public class SubwayStrategy implements Strategy {@Override
    public void travel() {Log.d("SubwayStrategy","travel");
    }
}

/**
 * Created by Administrator on 2017/9/15.
 */

public class WalkStrategy implements Strategy{@Override
    public void travel() {Log.d("WalkStrategy","travel");
    }
}

public class TravelContext {Strategy strategy;

    public Strategy getStrategy() {return strategy;
    }public void setStrategy(Strategy strategy) {this.strategy = strategy;
    }public void travel() {if (strategy != null) {strategy.travel();
        }}}