Java实现多字段分组，多字段求和（下）

妖狐艹你老母 2021-09-07 06:18 887阅读 0赞

# 一 需求 #

分组的多个字段有：员工ID、员工编码、员工名称、考勤配置ID、考勤配置名称。

统计的多个字段有：总条数、总的工作小时数、实际的小时数。

通过分组字段求算统计字段。

# 二 代码 #

import lombok.Data;
    import org.springframework.beans.BeanUtils;
    
    import java.util.ArrayList;
    import java.util.List;
    import java.util.Map;
    import java.util.stream.Collectors;
    
    /**
    * @className: AttendanceStatisticByDayDTO
    * @description: 包含 分组字段 和 统计字段
    * @date: 2021/3/14
    * @author: cakin
    */
    @Data
    class AttendanceStatisticByDayDTO {
        // 分组字段开始
        /**
         * 员工ID
         */
        private String userId;
        /**
         * 员工编码
         */
        private String userCode;
        /**
         * 员工名称
         */
        private String userName;
        /**
         * 考勤配置ID
         */
        private String attendanceTypeId;
        /**
         * 考勤配置名称
         */
        private String attendanceTypeName;
        // 分组字段结束
    
        // 统计字段开始
        /**
         * 应上时长
         */
        private Double workDueHour;
        /**
         * 实上时长
         */
        private Double workRealHour;
        /**
         * 统计次数
         */
        private Long statisticTimes;
        // 统计字段结束
    }
    
    /**
    * @className: ComputeGroupByDTO
    * @description: 统计字段
    * @date: 2021/3/14
    * @author: cakin
    */
    @Data
    class ComputeGroupByDTO {
        /**
         * 总条数
         */
        private Long totalCount;
    
        /**
         * 总的工作小时数
         */
        private Double dueHourSum;
    
        /**
         * 真实的小时数
         */
        private Double realHourSum;
    }
    
    /**
    * @ClassName: GroupSumManyToMany
    * @Description: 多字段分组，多字段求和  参考：https://blog.csdn.net/qq_38428623/article/details/103754446
    * @Date: 2021/3/14
    * @Author: cakin
    */
    public class GroupSumManyToMany {
        /**
         * 功能描述：得到分组字段
         *
         * @param attendanceStatisticByDayDTO 考勤统计
         * @return 返回分组的KEY
         */
        private static AttendanceStatisticByDayDTO fetchGroupKey(final AttendanceStatisticByDayDTO attendanceStatisticByDayDTO) {
            final AttendanceStatisticByDayDTO statisticByDay = new AttendanceStatisticByDayDTO();
            statisticByDay.setUserId(attendanceStatisticByDayDTO.getUserId()); // 员工ID
            statisticByDay.setUserCode(attendanceStatisticByDayDTO.getUserCode()); // 员工编码
            statisticByDay.setUserName(attendanceStatisticByDayDTO.getUserName()); // 员工名称
            statisticByDay.setAttendanceTypeId(attendanceStatisticByDayDTO.getAttendanceTypeId()); // 考勤配置ID
            statisticByDay.setAttendanceTypeName(attendanceStatisticByDayDTO.getAttendanceTypeName()); // 考勤配置名称
            return statisticByDay;
        }
    
        /**
         * 功能描述：测试多字段分组，多字段求和
         *
         * @param args 命令行
         * @author cakin
         * @date 2021/3/14
         */
        public static void main(final String[] args) {
            final List<AttendanceStatisticByDayDTO> attendanceStatisticByDayDTOS = new ArrayList<>();
            // 初始化数据
            for (long i = 0; i < 100; i++) {
                final AttendanceStatisticByDayDTO attendanceStatisticByDayDTO = new AttendanceStatisticByDayDTO();
                attendanceStatisticByDayDTO.setUserId("" + (i % 5));
                attendanceStatisticByDayDTO.setUserCode("" + (i % 5));
                attendanceStatisticByDayDTO.setUserName("" + (i % 5));
                attendanceStatisticByDayDTO.setWorkDueHour((double) (i % 5));
                attendanceStatisticByDayDTO.setWorkRealHour((double) (i % 5));
                attendanceStatisticByDayDTO.setStatisticTimes(i);
                attendanceStatisticByDayDTO.setAttendanceTypeId("" + (i % 5));
                attendanceStatisticByDayDTO.setAttendanceTypeName("" + (i % 5));
                attendanceStatisticByDayDTOS.add(attendanceStatisticByDayDTO);
            }
    
            /**
             * 获取分组结果
             * 分组字段:员工ID、员工编码、员工名称、考勤配置ID、考勤配置名称,通过 fetchGroupKey 获取
             * 统计字段：通过 collectingAndThen 的第2个参数定义统计方式
             */
            final Map<AttendanceStatisticByDayDTO, ComputeGroupByDTO> groupByMap =
                    attendanceStatisticByDayDTOS
                            .stream()
                            .collect(Collectors.groupingBy(n -> fetchGroupKey(n), Collectors.collectingAndThen(Collectors.toList(), m -> {
                                // totalCount 采用计数方式
                                final long totalCount = m.stream().count();
                                // dueHourSum 采用求和方式
                                final Double dueHourSum = m.stream().mapToDouble(AttendanceStatisticByDayDTO::getWorkDueHour).sum();
                                // realHourSum 采用求和方式
                                final Double realHourSum = m.stream().mapToDouble(AttendanceStatisticByDayDTO::getWorkDueHour).sum();
                                final ComputeGroupByDTO computeGroupBy = new ComputeGroupByDTO();
                                computeGroupBy.setTotalCount(totalCount); // 计数
                                computeGroupBy.setDueHourSum(dueHourSum); // 求和
                                computeGroupBy.setRealHourSum(realHourSum); // 求和
                                return computeGroupBy;
                            })));
            System.out.println("===============结果大小===============================");
            System.out.println("groupByMap=" + groupByMap.size());
    
            List<AttendanceStatisticByDayDTO> list = new ArrayList<>();
            System.out.println("===============中间结果===============================");
            groupByMap.forEach((k, v) -> {
                System.out.println(k);
                System.out.println(v);
                AttendanceStatisticByDayDTO attendanceStatisticByDayDTO = new AttendanceStatisticByDayDTO();
                BeanUtils.copyProperties(k, attendanceStatisticByDayDTO);
                attendanceStatisticByDayDTO.setStatisticTimes(v.getTotalCount());
                attendanceStatisticByDayDTO.setWorkDueHour(v.getDueHourSum());
                attendanceStatisticByDayDTO.setWorkRealHour(v.getRealHourSum());
                list.add(attendanceStatisticByDayDTO);
            });
    
            System.out.println("===============最终结果===============================");
            for (AttendanceStatisticByDayDTO attendanceStatisticByDayDTO : list) {
                System.out.println(attendanceStatisticByDayDTO);
            }
        }
    }

# 三 测试 #

===============结果大小===============================
    groupByMap=5
    ===============中间结果===============================
    AttendanceStatisticByDayDTO(userId=2, userCode=2, userName=2, attendanceTypeId=2, attendanceTypeName=2, workDueHour=null, workRealHour=null, statisticTimes=null)
    ComputeGroupByDTO(totalCount=20, dueHourSum=40.0, realHourSum=40.0)
    AttendanceStatisticByDayDTO(userId=4, userCode=4, userName=4, attendanceTypeId=4, attendanceTypeName=4, workDueHour=null, workRealHour=null, statisticTimes=null)
    ComputeGroupByDTO(totalCount=20, dueHourSum=80.0, realHourSum=80.0)
    AttendanceStatisticByDayDTO(userId=0, userCode=0, userName=0, attendanceTypeId=0, attendanceTypeName=0, workDueHour=null, workRealHour=null, statisticTimes=null)
    ComputeGroupByDTO(totalCount=20, dueHourSum=0.0, realHourSum=0.0)
    AttendanceStatisticByDayDTO(userId=3, userCode=3, userName=3, attendanceTypeId=3, attendanceTypeName=3, workDueHour=null, workRealHour=null, statisticTimes=null)
    ComputeGroupByDTO(totalCount=20, dueHourSum=60.0, realHourSum=60.0)
    AttendanceStatisticByDayDTO(userId=1, userCode=1, userName=1, attendanceTypeId=1, attendanceTypeName=1, workDueHour=null, workRealHour=null, statisticTimes=null)
    ComputeGroupByDTO(totalCount=20, dueHourSum=20.0, realHourSum=20.0)
    ===============最终结果===============================
    AttendanceStatisticByDayDTO(userId=2, userCode=2, userName=2, attendanceTypeId=2, attendanceTypeName=2, workDueHour=40.0, workRealHour=40.0, statisticTimes=20)
    AttendanceStatisticByDayDTO(userId=4, userCode=4, userName=4, attendanceTypeId=4, attendanceTypeName=4, workDueHour=80.0, workRealHour=80.0, statisticTimes=20)
    AttendanceStatisticByDayDTO(userId=0, userCode=0, userName=0, attendanceTypeId=0, attendanceTypeName=0, workDueHour=0.0, workRealHour=0.0, statisticTimes=20)
    AttendanceStatisticByDayDTO(userId=3, userCode=3, userName=3, attendanceTypeId=3, attendanceTypeName=3, workDueHour=60.0, workRealHour=60.0, statisticTimes=20)
    AttendanceStatisticByDayDTO(userId=1, userCode=1, userName=1, attendanceTypeId=1, attendanceTypeName=1, workDueHour=20.0, workRealHour=20.0, statisticTimes=20)