jdk8 stream的分组功能list.stream().collect(Collectors.groupingBy(对象Vo::分组标志字段))
list.stream().collect(Collectors.groupingBy(对象Vo::分组标志字段));业务场景:表结构大概这个样子:前端返回样式{1:[{key:value,key:value,…},{key:value,key:value,…},…],2:[{key:value,key:value,…},{key:value,key:value,…},…],}SQL写起来的话gr