字符串 Instant 互转

Instant inst = Instant.now();
System.out.println(inst);//2018-05-15T02:27:09.909Z

String s1 = s.substring(0, 11).concat("20:13:00.000Z");
System.out.println(s1);//2018-05-15T20:13:00.000Z

Instant instant = Instant.parse(Instant.now().toString().substring(0, 11).concat("20:13:00Z"));
System.out.println(instant);//2018-05-15T20:13:00Z

Instant instant = Instant.parse("1995-10-23T20:12:35Z");
System.out.println(instant);//1995-10-23T20:12:35Z

System.out.println(instant.atZone(ZoneId.systemDefault()));//1995-10-24T04:12:35+08:00[Asia/Shanghai]

System.out.println(instant.atOffset(ZoneOffset.ofHours(8)));//1995-10-24T04:12:35+08:00

System.out.println(ISO_DATE_TIME.withZone(UTC).format(Instant.now().truncatedTo(DAYS)));//2018-09-04T00:00:00Z

System.out.println(ISO_DATE.format(BASIC_ISO_DATE.parse("20111203")));//2011-12-03

import java.text.DateFormat;
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.time.ZoneOffset;
import java.time.format.DateTimeFormatter;

public static void main(String[] args) {
  System.out.println(parse(Instant.now()));

System.out.println(Instant.now());
    System.out.println(LocalDateTime.now());

  System.out.println((LocalDateTime.now().atZone(ZoneId.systemDefault())));
  System.out.println((LocalDateTime.now().atOffset(ZoneOffset.ofHours(8))));
}
private static  String parse(Instant instance) {
  DateTimeFormatter target =
      DateTimeFormatter.ofPattern("yyyy-MM-dd'T'HH:mm:ss.SSSZ").withZone(ZoneId.systemDefault());
  return target.format(instance);
}

2018-09-19T14:38:56.561+0800
2018-09-19T06:38:56.776Z
2018-09-19T14:38:56.776
2018-09-19T14:38:56.779+08:00[Asia/Shanghai]
2018-09-19T14:38:56.784+08:00

  public static void main(String[] args) {
    System.out.println(parse("2018-09-18T19:01:51.821-04:00"));
    System.out.println(parse(1537311711821L));
  }

  private static OffsetDateTime parse(long instance) {
    return Instant.ofEpochMilli(instance).atOffset(ZoneOffset.ofHours(-4));
  }

  private static long parse(String instance) {
    OffsetDateTime time = OffsetDateTime.parse(instance);
    return time.toInstant().toEpochMilli();
  }

1537311711821
2018-09-18T19:01:51.821-04:00