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

Posted 2022-12-05 赵侠客

• 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