Java8流操作

1. 双层Map+一层List

代码片

        // 开始分组Map<String, Map<Object, List<ProjectGeographyVO>>> collect4 = vos.stream()//  注释了下行没用市级项目,只有区// .filter(data -> String.valueOf(data.getCode()).length() == 6).collect(Collectors.groupingBy(entry -> entry.getCode().substring(0, 4),Collectors.groupingBy(ProjectGeographyVO::getCode)));

Json结构

{"3701": {"3701": [],"370116": [{"code": "3701","x": "117.114015649688620","y": "36.651616059305010"},{}]},"3702": {"3702": [],"370202": [],"370203": []}
}