Java设计模式之策略模式详解和示例

public interface Strategy {
    /**
     * 人类怎么吃饭的
     */
   public void eat();
}

public class Context {
    private Strategy strategy;
    public Context(){
    }
    public Context(Strategy strategy){
        this.strategy = strategy;
    }
    public void  setStrategy(Strategy strategy){
        this.strategy = strategy;
    }
    public void eat(){
        strategy.eat();
    }
}

 
 /**
 * 美国人 吃饭
 */
@Component
public class StrategyImplOne implements Strategy{
    @Override
    public void eat() {
        System.out.println("美国人用刀叉吃饭");
    }
}

/**
 * 中国人 吃饭
 */
@Component
public class StrategyImplTwo implements Strategy{
    @Override
    public void eat() {
        System.out.println("中国人用筷子吃饭");
    }
}

public class MainTest {
    public  static  void test(){
        Context context = new Context();
        context.setStrategy(new StrategyImplOne());
        context.eat();
        context.setStrategy(new StrategyImplTwo());
        context.eat();
    }
    public static void main(String[] args) {
        test();
    }
}

public enum ManType {
    AMERICAN(1,"American",StrategyImplOne.class),
    CHINESE(1,"Chinese",StrategyImplTwo.class)
    ;
    private Integer code;
    private String type;
    private Class classModel;
    // 定义一个Map 开始的时候就把这信息存储到这里面
    private static HashMap<String,Class> map = new HashMap<>(16);
    static {
        for ( ManType manType:ManType.values()) {
            map.put(manType.getType(),manType.getClassModel());
        }
    }
    ManType(Integer code, String type, Class classModel) {
        this.code = code;
        this.type = type;
        this.classModel = classModel;
    }
    public Integer getCode() {
        return code;
    }
    public String getType() {
        return type;
    }
    public Class getClassModel() {
        return classModel;
    }
    // 这个方法根据type获取指定的类 通过反射来 创建对象
    public static Class getManType(String type){
        return map.get(type);
    }
}

public class MainTest {
    public   void test(String manType){
        Context context = new Context();
        try {
            Strategy strategy = (Strategy) (ManType.getManType(manType).newInstance());
            context.setStrategy(strategy);
            context.eat();
        } catch (InstantiationException e) {
            e.printStackTrace();
        } catch (IllegalAccessException e) {
            e.printStackTrace();
        }
    }
    public static void main(String[] args) {
        new MainTest().test("American");
    }
}