策略模式

[louzhedong]

策略模式

定义一组算法，将每个算法都封装起来，并且使它们之间可以互换

优点：

算法可以自由切换

避免使用多重条件判断

扩展性良好

缺点：

策略类数量增多

所有的策略类都需要对外暴露

实现

Java

/**
 * 策略接口
 **/
public interface Strategy {
     void doSomething();
}

/**
 * 具体策略类
 **/
public class ConcreteStrategy implements Strategy {
    @Override
    public void doSomething() {

    }
}

/**
 * 执行类
 **/
public class Context {
    private Strategy strategy = null;

    public Context(Strategy _strategy) {
        this.strategy = _strategy;
    }

    public void doAnything() {
        this.strategy.doSomething();
    }
}

/**
 * 场景类
 **/
public class Client {
    public static void main(String[] args) {
        Strategy strategy = new ConcreteStrategy();

        Context context = new Context(strategy);

        context.doAnything();
    }
}

JavaScript

var strategies = {
  "S": function (salary) {
    return salary * 4;
  },
  "A": function (salary) {
    return salary * 3;
  },
  "B": function (salary) {
    return salary * 2;
  }
}

var calculateBonus = function (level, salary) {
  return strategies[level][salary];
}