Java8

1、LocalDateTime获取时间戳（毫秒/秒）、

2、Date与LocalDateTime互转

3、LocalDateTime与自定义的时间格式的字符串String互转

4、long类型的timestamp与LocalDateTime互转

1、LocalDateTime获取毫秒数

//获取秒数
Long second = LocalDateTime.now().toEpochSecond(ZoneOffset.of("+8"));

//获取毫秒数
Long milliSecond = LocalDateTime.now().toInstant(ZoneOffset.of("+8")).toEpochMilli();

2、Date与LocalDateTime互转

    //将java.util.Date 转换为java8 的java.time.LocalDateTime,默认时区为东8区
    public static LocalDateTime dateConvertToLocalDateTime(Date date) {
        return date.toInstant().atOffset(ZoneOffset.of("+8")).toLocalDateTime();
    }

   
    //将java8 的 java.time.LocalDateTime 转换为 java.util.Date，默认时区为东8区
    public static Date localDateTimeConvertToDate(LocalDateTime localDateTime) {
        return Date.from(localDateTime.toInstant(ZoneOffset.of("+8")));
    }

3.将LocalDateTime转为自定义的时间格式的字符串

public static String getDateTimeAsString(LocalDateTime localDateTime, String format) {
　　DateTimeFormatter formatter = DateTimeFormatter.ofPattern(format);
　　return localDateTime.format(formatter);
}

4.将某时间字符串转为自定义时间格式的LocalDateTime

public static LocalDateTime parseStringToDateTime(String time, String format) {
　　DateTimeFormatter df = DateTimeFormatter.ofPattern(format);
　　return LocalDateTime.parse(time, df);
}

5.将long类型的timestamp转为LocalDateTime

public static LocalDateTime getDateTimeOfTimestamp(long timestamp) {
　　Instant instant = Instant.ofEpochMilli(timestamp);
　　ZoneId zone = ZoneId.systemDefault();
　　return LocalDateTime.ofInstant(instant, zone);
}

6.将LocalDateTime转为long类型的timestamp

public static long getTimestampOfDateTime(LocalDateTime localDateTime) {
　　ZoneId zone = ZoneId.systemDefault();
　　Instant instant = localDateTime.atZone(zone).toInstant();
　　return instant.toEpochMilli();
}

时间工具类：DateUtil.java

public class DateUtil {
	private static final long ONE_DAY=24*60*60*1000;
	
	private static final String DATE_FORMAT1="yyyy-MM-dd";
	private static final String DATE_FORMAT2="yyyyMMdd";
	private static final String DATETIME_FORMAT1="yyyy-MM-dd HH:mm:ss";
	private static final String DATETIME_FORMAT2="yyyyMMddHHmmss";
	private static final String DATETIME_FORMAT3="yyyy-MM-dd HH:mm:ss.SSS";
	private static final String DATETIME_FORMAT4="yyyyMMddHHmmssSSS";

	private static final String TIME_FORMAT1="HH:mm:ss";
	
	

	//获取当前时间(字符串格式)
	public static getCurrentDateTime(String format){
		DateTimeFormatter formatter = DateTimeFormatter.ofPattern(format);
		return LocalDateTime.now().format(formatter);
	}
	
    //获取昨天时间格式
	public static getYesterdayByFormat(String format){
		DateTimeFormatter formatter = DateTimeFormatter.ofPattern(format);
		return LocalDateTime.now().minusDays(1).format(formatter);
	}

	//获取从1970年1月1日到现在的秒数
	public static Long getSecond(String dateTime,String format){
		DateTimeFormatter dtf = DateTimeFormatter.ofPattern(format);
		LocalDateTime localDateTime = LocalDateTime.parse(dateTime,dtf);
		Long second = localDateTime.toEpochSecond(ZoneOffset.of("+8"));
		return second;
	}

	//LocalDateTime转String
	public static String getLocalDateTimeToStr(LocalDateTime localDateTime, String format){
		DateTimeFormatter dtf = DateTimeFormatter.ofPattern(format);
		return localDateTime.format(dtf);
	}

	//获取从1970年1月1日到现在的秒数转LocalDateTime
	public static LocalDateTime getSecondToLocalDateTime(Long second) {
		Instant instant = Instant.ofEpochSecond(second);
		ZoneId zoneId = ZoneId.systemDefault();
		return LocalDateTime.ofInstant(instant, zoneId);
	}

	//获取从1970年1月1日到现在的秒数转字符串格式
    public static String getSecondToStr(long second, String format){
		return getLocalDateTimeToStr(getSecondToLocalDateTime(second),format)
	}
}