Java设计模式之策略模式

Java设计模式之策略模式

首先定义一个策略接口

public interface IStrategy {
    //定义具体策略必须具有的方法
    public void doSomething();
}

定义子类实现接口

public class ConcreteStrategy1 implements IStrategy{
    public void doSomething(){
        System.out.println("this is a concreteStrategy");
    }
}

public class ConcreteStrategy2 implements IStrategy{
    @Override
    public void doSomething() {
        System.out.println("This is concreteStrategy2");
    }
}

定义全局上下文

public class Context {
    private IStrategy strategy;
    public Context(IStrategy strategy){
        this.strategy = strategy;
    }
    public void doSomething(){
        this.strategy.doSomething();
    }
}

定义一个枚举类

public enum StrategyMan {
    Strategy1("com.strategy.ConcreteStrategy1"),
    Strategy2("com.strategy.ConcreteStrategy2");
    String value = "";
    private StrategyMan(String value){
        this.value = value;
    }
    public String getValue(){
        return this.value;
    }
}

定义一个策略工厂

public class StrategyFactory {
    public static IStrategy getStrategy(StrategyMan strategyman){
        IStrategy strategy = null;
        try {
            strategy = (IStrategy) Class.forName(strategyman.getValue()).newInstance();
        } catch (Exception) {
            e.printStackTrace();
        }
        return strategy;
    }
}

public class StrategyFacade {
    public void doSomething(String str){
        StrategyMan sMan = StrategyMan.valueOf(str);
        IStrategy strategy = StrategyFactory.getStrategy(sMan);
        Context context = new Context(strategy);
        context.doSomething();
    }
}

public class Client {

    public static void main(String[] args) {
        StrategyFacade sFacade = new StrategyFacade();
        sFacade.doSomething("Strategy1");
    }
}

总结：

• 首先定义一个策略接口；
• 然后让一些子类实现这个接口，每一种策略就是一个子类；
• 然后再定义一个枚举类来创建所需要的子类，再通过工厂的方式来生产策略类。