spring策略模式

public interface Strategy {


    /**
     * 调用策略方法
     * @param strategyParam 执行策略方案参数
     * @return 业务处理返回结果封装实体
     */
    AjaxResult invokeStrategy(StrategyParam strategyParam);

    /**
     * 获取当前对象对应枚举
     * @return 策略枚举
     */
    StrategyEnum getStrategyEnum();
}

/**
 * @author YUFEI
 * @Date 2022/9/19 9:11
 * @Version 1.0
 */
@Service(value = "strategyA")
@BusinessStrategy
public class StrategyA implements Strategy {
    @Override
    public AjaxResult invokeStrategy(StrategyParam strategyParam) {

        System.out.println("正在执行StrategyA......");
        return null;
    }

    @Override
    public StrategyEnum getStrategyEnum() {
        return StrategyEnum.STRATEGY_A;
    }
}

@Service(value = "strategyB")
@BusinessStrategy
public class StrategyB implements Strategy {

    @Override
    public AjaxResult invokeStrategy(StrategyParam strategyParam) {

        System.out.println("正在执行StrategyB......");
        return null;
    }

    @Override
    public StrategyEnum getStrategyEnum() {
        return StrategyEnum.STRATEGY_B;
    }
}

@Component
public class StrategyContext {

    public static Map strategyMap = new ConcurrentHashMap<>(16);

    /**
     * 执行策略上下文
     * @param strategyParam 策略参数
     * @return 业务处理返回封装实体
     */
    public AjaxResult invokeContext(StrategyParam strategyParam){

        if (strategyParam == null){
            throw new IllegalArgumentException("执行策略参数不能为空");
        }

        // 获取策略参数中枚举实例
        StrategyEnum strategyEnum = strategyParam.getStrategyEnum();

        // 通过枚举实例Get对应策略类
        Strategy strategy = strategyMap.get(strategyEnum);
         if(strategy==null){
             throw new IllegalArgumentException("策略实现类不存在");
         }
        // 执行策略方案
        return strategy.invokeStrategy(strategyParam);
    }
}

import com.cdkj.common.enums.StrategyEnum;
import com.cdkj.framework.annotation.BusinessStrategy;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.BeansException;
import org.springframework.beans.factory.config.BeanPostProcessor;
import org.springframework.stereotype.Component;

/**
 * 策略类管理器
 * @author ChenErGao
 */
@Component
public class StrategyManage implements BeanPostProcessor {
    private final static Logger log = LoggerFactory.getLogger(StrategyManage.class);
    @Override
    public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException {

        // 一定要将Bean实例返回
        return bean;
    }

    @Override
    public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {

        // 判断Bean是否被自定义注解标示
        if (bean instanceof Strategy && bean.getClass().isAnnotationPresent(BusinessStrategy.class)){

            // 将策略类强转为顶层策略接口
            Strategy strategy = (Strategy) bean;

            StrategyEnum strategyEnum= strategy.getStrategyEnum();
            if(strategyEnum==null){
                log.warn("######[StrategyManage]#################");
            }
            // 将策略类添加到策略Map中
            StrategyContext.strategyMap.put(strategy.getStrategyEnum(), strategy);
        }

        // 一定要把Bean实例返回
        return bean;
    }
}

/**
 * @author YUFEI
 * @Date 2022/9/19 9:11
 * @Version 1.0
 */
public class StrategyParam {
    StrategyEnum strategyEnum;

    public StrategyEnum getStrategyEnum() {
        return strategyEnum;
    }

    public void setStrategyEnum(StrategyEnum strategyEnum) {
        this.strategyEnum = strategyEnum;
    }
}