基于Java8 LocalDateTime/LocalDate封装的时间工具类（多个时间类型转换）

朴灿烈づ我的快乐病毒、 2023-07-13 04:10 3阅读 0赞

## 写在前面 ##

封装了常用时间的相互转换，以及常用时间的常见格式化

## 工具类实现 ##

package tonels.util;
    
    import com.alibaba.excel.util.StringUtils;
    
    import java.text.ParseException;
    import java.text.SimpleDateFormat;
    import java.time.Instant;
    import java.time.LocalDate;
    import java.time.LocalDateTime;
    import java.time.ZoneId;
    import java.util.Date;
    
    public class DateUtils { 
    
        // ======以下为常用时间转换===================
        public static Date asDate(LocalDate localDate) { 
            return Date.from(localDate.atStartOfDay().atZone(ZoneId.systemDefault()).toInstant());
        }
    
        public static Date asDate(LocalDateTime localDateTime) { 
            return Date.from(localDateTime.atZone(ZoneId.systemDefault()).toInstant());
        }
    
        public static LocalDate asLocalDate(Date date) { 
            return Instant.ofEpochMilli(date.getTime()).atZone(ZoneId.systemDefault()).toLocalDate();
        }
    
        public static LocalDateTime asLocalDateTime(Date date) { 
            return Instant.ofEpochMilli(date.getTime()).atZone(ZoneId.systemDefault()).toLocalDateTime();
        }
    
        // =======以上为常用时间转换=====================
        // ==============以下为常用时间和String的转换=====================
        public static final String DATE_FORMAT_10 = "yyyy-MM-dd";
        public static final String DATE_FORMAT_14 = "yyyyMMddHHmmss";
        public static final String DATE_FORMAT_17 = "yyyyMMdd HH:mm:ss";
        public static final String DATE_FORMAT_19 = "yyyy-MM-dd HH:mm:ss";
        public static final String DATE_FORMAT_19_FORWARD_SLASH = "yyyy/MM/dd HH:mm:ss";
        private static final String MINUS = "-";
    
        private DateUtils() { 
        }
    
        /** * convert string to date * * @param dateString * @param dateFormat * @return * @throws ParseException */
        public static Date parseDate(String dateString, String dateFormat) throws ParseException { 
            if (StringUtils.isEmpty(dateFormat)) { 
                dateFormat = switchDateFormat(dateString);
            }
            return new SimpleDateFormat(dateFormat).parse(dateString);
        }
    
        /** * convert string to date * * @param dateString * @return * @throws ParseException */
        public static Date parseDate(String dateString) throws ParseException { 
            return parseDate(dateString, switchDateFormat(dateString));
        }
    
        /** * switch date format * * @param dateString * @return */
        private static String switchDateFormat(String dateString) { 
            int length = dateString.length();
            switch (length) { 
                case 19:
                    if (dateString.contains(MINUS)) { 
                        return DATE_FORMAT_19;
                    } else { 
                        return DATE_FORMAT_19_FORWARD_SLASH;
                    }
                case 17:
                    return DATE_FORMAT_17;
                case 14:
                    return DATE_FORMAT_14;
                case 10:
                    return DATE_FORMAT_10;
                default:
                    throw new IllegalArgumentException("can not find date format for：" + dateString);
            }
        }
    
        /** * Format date * <p> * yyyy-MM-dd HH:mm:ss * * @param date * @return */
        public static String format(Date date) { 
            return format(date, null);
        }
    
        /** * Format date * * @param date * @param dateFormat * @return */
        public static String format(Date date, String dateFormat) { 
            if (date == null) { 
                return "";
            }
            if (StringUtils.isEmpty(dateFormat)) { 
                dateFormat = DATE_FORMAT_19;
            }
            return new SimpleDateFormat(dateFormat).format(date);
        }
    
    
        // 这里是 Java8中时间和String的转化
        public static String format(LocalDate localDate, String dateFormat) { 
            Date date = asDate(localDate);
            if (date == null) { 
                return "";
            }
            if (StringUtils.isEmpty(dateFormat)) { 
                dateFormat = DATE_FORMAT_19;
            }
            return new SimpleDateFormat(dateFormat).format(date);
        }
    
        public static String format(LocalDateTime localDateTime, String dateFormat) { 
            Date date = asDate(localDateTime);
            if (date == null) { 
                return "";
            }
            if (StringUtils.isEmpty(dateFormat)) { 
                dateFormat = DATE_FORMAT_19;
            }
            return new SimpleDateFormat(dateFormat).format(date);
        }
    
        // String 转 LocalDate/LocalDateTime
        public static LocalDate parseLocalDate(String dateString) throws ParseException { 
            Date date = parseDate(dateString, switchDateFormat(dateString));
            return asLocalDate(date);
        }
    
        public static LocalDateTime parseLocalDateTime(String dateString) throws ParseException { 
            Date date = parseDate(dateString, switchDateFormat(dateString));
            return asLocalDateTime(date);
        }
    }