spring boot 中自定义注解，并通过注解反射获取类实例

深碍√TFBOYSˉ_ 2022-06-02 09:58 1229阅读 0赞

package com.eg.egsc.scp.accesscontrolcomponent.mq.iotmq;
    
    import org.slf4j.Logger;
    import org.slf4j.LoggerFactory;
    import org.springframework.amqp.core.Message;
    import org.springframework.amqp.rabbit.annotation.RabbitListener;
    import org.springframework.stereotype.Component;
    
    import com.alibaba.fastjson.JSONObject;
    import com.eg.egsc.scp.accesscontrolcomponent.SpringUtils;
    import com.eg.egsc.scp.accesscontrolcomponent.handler.AbstractMessageHandler;
    import com.eg.egsc.scp.accesscontrolcomponent.util.AnnoManageUtils;
    
    @Component
    public class ReceiverListenerIotbus {
      protected final Logger logger = LoggerFactory.getLogger(this.getClass());
    
      @RabbitListener(queues = "MSG_OUTBOUND_APP8075", containerFactory = "iotbusFactory")
      public void processMap(Message message) {
        String busMsg = new String(message.getBody());
        logger.info("recevie form gateway：{}", busMsg);
        JSONObject jsonObject = JSONObject.parseObject(busMsg);
        // 如果上传的事件类型不包含事件id,则不处理业务逻辑
        if (!jsonObject.containsKey("eventTypeID")) {
          return;
        }
        Integer eventTypeId = jsonObject.getInteger("eventTypeID");
        String beanName = AnnoManageUtils.getBeanNameByEventType(eventTypeId);
        // 接收的事件类型找不到对应的业务处理，不进行业务处理
        if (null == beanName) {
          return;
        }
        try {
          AbstractMessageHandler messageHandler = (AbstractMessageHandler) SpringUtils.getBean(beanName);
          // 注入对应的类进行业务处理
          messageHandler.doProcess(message);
        } catch (Exception e) {
          logger.error("接收mq信息出错{}",e);
        }
      }
    
    }

自定义注解

@Retention(RetentionPolicy.RUNTIME)
    @Documented
    public @interface Handler {
      String[] value() default "";
    }

public final class AnnoManageUtils {
      public static Map<Integer, String> map = new ConcurrentHashMap<Integer, String>();
    
      static {
        //反射工具包，指明扫描路径
        Reflections reflections = new Reflections("com.eg.egsc.scp.accesscontrolcomponent.handler");
        //获取带Handler注解的类
        Set<Class<?>> classList = reflections.getTypesAnnotatedWith(Handler.class);
        for (Class classes : classList) {
          Handler t = (Handler) classes.getAnnotation(Handler.class);
          String[] valueList = t.value();
          //获取注解的值并循环
          for (String value : valueList) {
            //注解值为key，类名为value
            map.put(Integer.valueOf(value), CommonUtils.normalizeFirstWord(classes.getSimpleName()));
          }
        }
      }
    
      //通过eventTypeId，也就是注解的值获取相应处理Handler的类名
      public static String getBeanNameByEventType(Integer eventTypeId) {
        return map.get(eventTypeId);
      }
    }

AnnoManageUtils通过Reflections反射工具包，获得所有添加handler注解的类。并存储在ConcurrentHashMap中，key为注解handler的值。这样就可以通过handler的值获取到handler注解的类名。再通过类名获取类注入到容器中的bean。

package com.eg.egsc.scp.accesscontrolcomponent;
    
    import org.springframework.context.ApplicationContext;
    import org.springframework.context.ApplicationContextAware;
    import org.springframework.stereotype.Component;
    
    @Component
    public class SpringUtils implements ApplicationContextAware {
      private static ApplicationContext applicationContext = null;
    
      @Override
      public void setApplicationContext(ApplicationContext applicationContext) {
        if (SpringUtils.applicationContext == null) {
          SpringUtils.applicationContext = applicationContext;
        }
      }
    
      // 获取applicationContext
      public static ApplicationContext getApplicationContext() {
        return applicationContext;
      }
    
      // 通过name获取 Bean.
      public static Object getBean(String name) {
        return getApplicationContext().getBean(name);
    
      }
    
      // 通过class获取Bean.
      public static <T> T getBean(Class<T> clazz) {
        return getApplicationContext().getBean(clazz);
      }
    
      // 通过name,以及Clazz返回指定的Bean
      public static <T> T getBean(String name, Class<T> clazz) {
        return getApplicationContext().getBean(name, clazz);
      }
    }