enum和Collection.stream()你这样用过么

用过么"/>

enum和Collection.stream()你这样用过么

最近在做一个数据图表展示的功能，显示订单近七天或者近半月的数量和金额。可以理解成下图所示的样子：

我是用枚举和集合的stream方法实现的数据初始化和组装，枚举用来动态初始化时间范围，集合的stream方法来将初始化的数据转换成map，以日期为key，然后查询数据库的数据组装到map中，组转完后返回数据即可。我觉得这个方法不错，特此记录一下。
流程如下：

模拟代码如下：

/*** 订单汇总测试*/
public class TransinfoSum {public static void main(String[] args) {// 模拟传参，前端传递显示近七天还是近半月，和枚举呼应int code = 1;// 初始化，根据code初始化日期范围List<Transinfo> transinfoList = new ArrayList<Transinfo>();for (int t=0; t<TimeTypeEnum.getTimeTypeEnum(code).getNum(); t++) {// 从当前日期往前减ttransinfoList.add(new Transinfo(DateUtils.dateTime(DateUtils.addDays(new Date(), -t))));}// list转mapMap<String, Transinfo> transinfoMap = transinfoList.stream().collect(Collectors.toMap(Transinfo::getDate, transinfo -> transinfo));// 模拟数据库数据List<Transinfo> transinfoListFromDB = new ArrayList<Transinfo>();// 开始组装数据for (Transinfo transinfo : transinfoListFromDB) {String date = transinfo.getDate();transinfoMap.get(date).setNum(transinfo.getNum());transinfoMap.get(date).setAmount(transinfo.getAmount());}// 返回数据即可}
}

初始化后的数据是这样的：

Transinfo{date='2023-11-03', num=0, amount=0}
Transinfo{date='2023-11-02', num=0, amount=0}
Transinfo{date='2023-11-01', num=0, amount=0}
Transinfo{date='2023-10-31', num=0, amount=0}
Transinfo{date='2023-10-30', num=0, amount=0}
Transinfo{date='2023-10-29', num=0, amount=0}
Transinfo{date='2023-10-28', num=0, amount=0}

全部代码如下：

/*** 枚举类，定义时间类型*/
public enum TimeTypeEnum {WEEK(1, "近七天", 7),FIFTEEN(2, "近半月", 15),MONTH(3, "近一月", 30);private int code;private String msg;private int num;TimeTypeEnum(int code, String msg, int num) {this.code = code;this.msg = msg;this.num = num;}public int getCode() {return code;}public String getMsg() {return msg;}public int getNum() {return num;}public static TimeTypeEnum getTimeTypeEnum(int code) {for (TimeTypeEnum timeTypeEnum : TimeTypeEnum.values()) {if (code == timeTypeEnum.getCode()) {return timeTypeEnum;}}return null;}
}

/*** 订单汇总*/
public class Transinfo {public Transinfo(){}public Transinfo(String date){this.date = date;this.num = 0;this.amount = BigDecimal.ZERO;}private String date;private Integer num;private BigDecimal amount;public String getDate() {return date;}public void setDate(String date) {this.date = date;}public Integer getNum() {return num;}public void setNum(Integer num) {this.num = num;}public BigDecimal getAmount() {return amount;}public void setAmount(BigDecimal amount) {this.amount = amount;}@Overridepublic String toString() {return "Transinfo{" +"date='" + date + '\'' +", num=" + num +", amount=" + amount +'}';}
}

/*** 订单汇总测试*/
public class TransinfoSum {public static void main(String[] args) {// 模拟传参int code = 1;// 初始化List<Transinfo> transinfoList = new ArrayList<Transinfo>();for (int t=0; t<TimeTypeEnum.getTimeTypeEnum(code).getNum(); t++) {transinfoList.add(new Transinfo(DateUtils.dateTime(DateUtils.addDays(new Date(), -t))));}// list转mapMap<String, Transinfo> transinfoMap = transinfoList.stream().collect(Collectors.toMap(Transinfo::getDate, transinfo -> transinfo));// 模拟数据库数据List<Transinfo> transinfoListFromDB = new ArrayList<Transinfo>();// 开始组装数据for (Transinfo transinfo : transinfoListFromDB) {String date = transinfo.getDate();transinfoMap.get(date).setNum(transinfo.getNum());transinfoMap.get(date).setAmount(transinfo.getAmount());}// 返回数据即可}
}

package com.exammon.utils;import java.lang.management.ManagementFactory;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.time.LocalDate;
import java.time.LocalDateTime;
import java.time.LocalTime;
import java.time.ZoneId;
import java.time.ZonedDateTime;
import java.util.Date;
import org.apachemons.lang3.time.DateFormatUtils;/*** 时间工具类* * @author ruoyi*/
public class DateUtils extends org.apachemons.lang3.time.DateUtils
{public static String YYYY = "yyyy";public static String YYYY_MM = "yyyy-MM";public static String YYYY_MM_DD = "yyyy-MM-dd";public static String YYYYMMDDHHMMSS = "yyyyMMddHHmmss";public static String YYYY_MM_DD_HH_MM_SS = "yyyy-MM-dd HH:mm:ss";private static String[] parsePatterns = {"yyyy-MM-dd", "yyyy-MM-dd HH:mm:ss", "yyyy-MM-dd HH:mm", "yyyy-MM", "yyyy/MM/dd", "yyyy/MM/dd HH:mm:ss", "yyyy/MM/dd HH:mm", "yyyy/MM","yyyy.MM.dd", "yyyy.MM.dd HH:mm:ss", "yyyy.MM.dd HH:mm", "yyyy.MM"};/*** 获取当前Date型日期* * @return Date() 当前日期*/public static Date getNowDate(){return new Date();}/*** 获取当前日期, 默认格式为yyyy-MM-dd* * @return String*/public static String getDate(){return dateTimeNow(YYYY_MM_DD);}public static final String getTime(){return dateTimeNow(YYYY_MM_DD_HH_MM_SS);}public static final String dateTimeNow(){return dateTimeNow(YYYYMMDDHHMMSS);}public static final String dateTimeNow(final String format){return parseDateToStr(format, new Date());}public static final String dateTime(final Date date){return parseDateToStr(YYYY_MM_DD, date);}public static final String parseDateToStr(final String format, final Date date){return new SimpleDateFormat(format).format(date);}public static final Date dateTime(final String format, final String ts){try{return new SimpleDateFormat(format).parse(ts);}catch (ParseException e){throw new RuntimeException(e);}}/*** 日期路径 即年/月/日 如2018/08/08*/public static final String datePath(){Date now = new Date();return DateFormatUtils.format(now, "yyyy/MM/dd");}/*** 日期路径 即年/月/日 如20180808*/public static final String dateTime(){Date now = new Date();return DateFormatUtils.format(now, "yyyyMMdd");}/*** 日期型字符串转化为日期 格式*/public static Date parseDate(Object str){if (str == null){return null;}try{return parseDate(str.toString(), parsePatterns);}catch (ParseException e){return null;}}/*** 获取服务器启动时间*/public static Date getServerStartDate(){long time = ManagementFactory.getRuntimeMXBean().getStartTime();return new Date(time);}/*** 计算相差天数*/public static int differentDaysByMillisecond(Date date1, Date date2){return Math.abs((int) ((date2.getTime() - date1.getTime()) / (1000 * 3600 * 24)));}/*** 计算时间差** @param endDate 最后时间* @param startTime 开始时间* @return 时间差（天/小时/分钟）*/public static String timeDistance(Date endDate, Date startTime){long nd = 1000 * 24 * 60 * 60;long nh = 1000 * 60 * 60;long nm = 1000 * 60;// long ns = 1000;// 获得两个时间的毫秒时间差异long diff = endDate.getTime() - startTime.getTime();// 计算差多少天long day = diff / nd;// 计算差多少小时long hour = diff % nd / nh;// 计算差多少分钟long min = diff % nd % nh / nm;// 计算差多少秒//输出结果// long sec = diff % nd % nh % nm / ns;return day + "天" + hour + "小时" + min + "分钟";}/*** 增加 LocalDateTime ==> Date*/public static Date toDate(LocalDateTime temporalAccessor){ZonedDateTime zdt = temporalAccessor.atZone(ZoneId.systemDefault());return Date.from(zdt.toInstant());}/*** 增加 LocalDate ==> Date*/public static Date toDate(LocalDate temporalAccessor){LocalDateTime localDateTime = LocalDateTime.of(temporalAccessor, LocalTime.of(0, 0, 0));ZonedDateTime zdt = localDateTime.atZone(ZoneId.systemDefault());return Date.from(zdt.toInstant());}
}