使用LocalDateTime解析带有微秒，纳秒时间格式yyyy-MM-dd'T'HH:mm:ss.SSSSSSZ

桃扇骨 2022-03-15 04:18 502阅读 0赞

**1.使用SimpleDateFormat解析带有微秒，纳秒格式的时间会出现多几分钟的现象，因为SimpleDateFormat只能解析到毫秒，会将微秒等当做毫秒来解析**  
**2.使用LocalDateTime来正确解析，JDK1.8后加入**

package javaTEST;
    
    import java.math.BigDecimal;
    import java.text.SimpleDateFormat;
    import java.time.LocalDateTime;
    import java.time.ZoneId;
    import java.time.ZonedDateTime;
    import java.time.format.DateTimeFormatter;
    import java.util.Calendar;
    import java.util.Date;
    
    public class Test2 
    { 
    	public static void main(String[] args) throws Exception
    	{ 
    		String valueIn = "2019-02-19T23:28:04.434410+0800";
    		String formatIn = "yyyy-MM-dd'T'HH:mm:ss.SSSSSSZ";
    		String formatOut = "yyyy-MM-dd HH:mm:ss";
    		String formatOut2 = "yyyy-MM-dd'T'HH:mm:ss.SSSSSSZ";
    		
    		//使用SimpleDateFormat解析
    		Date date= new SimpleDateFormat(formatIn).parse(valueIn);
    		String out1= new SimpleDateFormat(formatOut).format(date);
    		System.out.println("SimpleDateFormat out:" + out1 +",会多几分钟");
    		
    		//使用LocalDateTime
    		//先获取时间纳秒
    		LocalDateTime ldt = LocalDateTime.parse(valueIn, DateTimeFormatter.ofPattern(formatIn));
    		ZonedDateTime zdt = ZonedDateTime.of(ldt, ZoneId.systemDefault());        
    		String out2 = DateTimeFormatter.ofPattern(formatOut).format(zdt);
    		System.out.println("LocalDateTime out:" + out2);
    		
    		//double类型时间2019-02-19T23:28:04.434410+0800=1550590084.434410还原yyyy-MM-dd'T'HH:mm:ss.SSSSSSZ
    		double d_time =  1550590084.434410;
    		BigDecimal bd = new BigDecimal(d_time).setScale(6,BigDecimal.ROUND_DOWN);
    		long Millitime = (long)(d_time*1000);
    		int Nano = Integer.parseInt(bd.toString().substring(bd.toString().indexOf(".")+1)+"000");
    		
    		Date date1= new Date(Millitime);
    		Calendar calendar = Calendar.getInstance();
    		calendar.setTime(date1);
    		int YEAR = calendar.get(Calendar.YEAR);
    		int MONTH = calendar.get(Calendar.MONTH)+1;
    		int DAY_OF_MONTH = calendar.get(Calendar.DAY_OF_MONTH);
    		int HOUR_OF_DAY = calendar.get(Calendar.HOUR_OF_DAY);
    		int MINUTE = calendar.get(Calendar.MINUTE);
    		int SECOND = calendar.get(Calendar.SECOND);
    		
    		LocalDateTime ldt2 = LocalDateTime.of(YEAR, MONTH, DAY_OF_MONTH, HOUR_OF_DAY, MINUTE, SECOND, Nano);
    		//必须要指定时区，要不然会报java.time.temporal.UnsupportedTemporalTypeException: Unsupported field: OffsetSeconds
    		ZonedDateTime zdt2 = ZonedDateTime.of(ldt2, ZoneId.systemDefault()); 
    		String out3 = DateTimeFormatter.ofPattern(formatOut2).format(zdt2);
    		System.out.println("LocalDateTime 1550590084.434410 out:" + out3);
    	}
    }

结果:

SimpleDateFormat out:2019-02-19 23:35:18,会多几分钟
    LocalDateTime out:2019-02-19 23:28:04
    LocalDateTime 1550590084.434410 out:2019-02-19T23:28:04.434410+0800