SpringBoot切换不同的实现时，出现nullPointer问题

约定不等于承诺〃 2023-02-22 05:08 7阅读 0赞

1，有时候算法需要迭代，相同的接口需要多个实现，自己可以随意切换，接口类：

package com.xxx.shortvideo.manager;
    
    
    
    public interface VideoRecommendedManger {
    
      FeedVideoByUserDTO getVideoByUser(FeedVideoByUserReq req);
    
    }

2, 针对接口有两个实现

![20200701181312978.png][]

3，通过配置config类来实现

package com.xxxx.shortvideo.config;
    
    import com.xxxx.shortvideo.enums.BizTypeEnum;
    import com.xxxx.shortvideo.manager.VideoRecommendedManger;
    import com.xxxx.shortvideo.manager.impl.VideoRecHotWordMangerImpl;
    import com.xxxx.shortvideo.manager.impl.VideoRecommendedMangerImpl;
    import com.google.common.collect.Maps;
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.context.ApplicationContext;
    import org.springframework.context.annotation.Bean;
    import org.springframework.context.annotation.Configuration;
    
    import java.util.Map;
    
    
    @Configuration
    public class ShortVideoFillServiceConfig {
    	
    	@Autowired
    	ApplicationContext applicationContext;
    	
    	@Bean
    	Map<String, VideoRecommendedManger> shortVideoRecServiceMap() {
    		Map<String, VideoRecommendedManger> shortVideoRecServiceMap = Maps.newHashMap();
    
    		shortVideoRecServiceMap.put(BizTypeEnum.SHORT_VIDEO_DEFAULT.getPrefix(), applicationContext.getBean(VideoRecommendedMangerImpl.class));
    		shortVideoRecServiceMap.put(BizTypeEnum.SHORT_VIDEO_HOT_WORD.getPrefix(), applicationContext.getBean(VideoRecHotWordMangerImpl.class));
    
    		return shortVideoRecServiceMap;
    	}
    
    }

4,调用具体的实现

import javax.annotation.Resource;
    import java.util.Map;
    
    @RestController
    @RequestMapping("/facade/shortvideo")
    @Slf4j
    public class FeedVideoController {
    
        @Resource
        Map<String, VideoRecommendedManger> shortVideoRecServiceMap;
    
        //根据用户，获取video的list
        @RequestMapping(value = "/recommend", method = RequestMethod.POST)
        @PermissionCheck(skipAop=true)
        @ResponseBody
        public Res<FeedVideoByUserDTO> getVideoListByUserReq(@RequestBody FeedVideoByUserReq req) {
    
            try {
                FeedVideoByUserDTO videoByUser = null;
    
                if((BizTypeEnum.SHORT_VIDEO_HOT_WORD.getPrefix()).equals(req.getFlowTo())) {
                    videoByUser = shortVideoRecServiceMap.get(BizTypeEnum.SHORT_VIDEO_HOT_WORD.getPrefix()).getVideoByUser(req);
                }else {
                    videoByUser = shortVideoRecServiceMap.get(BizTypeEnum.SHORT_VIDEO_DEFAULT.getPrefix()).getVideoByUser(req);
                }
                log.info(String.format("用户推荐视频调用成功，返回：[%s]", JSON.toJSONString(videoByUser)));
                return Res.wrapSuccessfulResult(videoByUser);
            } catch (Exception e) {
                e.printStackTrace();
            }
            return Res.wrapErrorResult(-1, "系统异常！");
    
        }
    
    }

**5，注意事项：**

5.1 如果 Map<String, HotelRecommendedManger>  hotelRecServiceMap为String 类型：则需要 @Resource修饰

5.2如果 Map<Integer, HotelRecommendedManger>  hotelRecServiceMap为Integer类型：则需要 @Autowire修饰

[20200701181312978.png]: https://img-blog.csdnimg.cn/20200701181312978.png