java8 lambda Stream 将分组后的对象所有字段相加得到一个对象

梦里梦外; 2023-07-21 11:20 5阅读 0赞

*  数据结构

现有多个对象，存储每个租户的视频/音频/图片大小，对象结构如下

public class TBucketSize  {
        private Long tenantId;
        private Long imgSize;
        private Long audioSize;
        private Long videoSize;
    }

租户数据如下：

TBucketSize tBucketSize1=new TBucketSize();
            tBucketSize1.setTenantId(1L);
            tBucketSize1.setAudioSize(1L);
            tBucketSize1.setVideoSize(0L);
            tBucketSize1.setImgSize(0L);
    
            TBucketSize tBucketSize2=new TBucketSize();
            tBucketSize2.setTenantId(1L);
            tBucketSize2.setVideoSize(1L);
            tBucketSize2.setAudioSize(1L);
            tBucketSize2.setImgSize(2L);
    
            TBucketSize tBucketSize3=new TBucketSize();
            tBucketSize3.setTenantId(2L);
            tBucketSize3.setImgSize(1L);
            tBucketSize3.setAudioSize(0L);
            tBucketSize3.setVideoSize(0L);
    
            TBucketSize tBucketSize4=new TBucketSize();
            tBucketSize4.setTenantId(2L);
            tBucketSize4.setImgSize(1L);
            tBucketSize4.setAudioSize(3L);
            tBucketSize4.setVideoSize(1L);
            List<TBucketSize> bucketSizes=        Arrays.asList(tBucketSize1,tBucketSize2,tBucketSize3,tBucketSize4);

*  需求

要求统计每个租户 视频/音频/图片用量

*  java stream lambda计算写法：

bucketSizes.stream().collect(Collectors.toMap(TBucketSize::getTenantId, Function.identity(), (u1, u2) -> {
                u1.setImgSize(u1.getImgSize() + u2.getImgSize());
                u1.setVideoSize(u1.getVideoSize() + u2.getVideoSize());
                u1.setAudioSize(u1.getAudioSize() + u2.getAudioSize());
                return u1;
            })).forEach((k, v) -> System.out.println(k+"-->"+ JSON.toJSON(v)));

*  输出结果

1-->{"audioSize":2,"imgSize":2,"isDelete":0,"videoSize":1,"tenantId":1}
    2-->{"audioSize":3,"imgSize":2,"isDelete":0,"videoSize":1,"tenantId":2}