Java8相当于Joda'；s ISODateTimeFormat.dateTimeParser（）？

我不知道如何让Java8的DateTime解析像我试图替换的Joda一样工作。问题是Joda的

ISODateTimeFormat.dateTimeParser（）允许我只输入YYYY，它仍然可以工作（例如，2016年将变成2016-01-01T00:00:00.000Z）。我如何从Java8获得相同的行为

代码很简单

import java.time.OffsetDateTime;
import java.time.temporal.ChronoField;

import org.joda.time.DateTime;
import org.joda.time.format.DateTimeFormatter;
import org.joda.time.format.ISODateTimeFormat;

public class Java8OffsetDateTime {
  public static void main(String[] args) {
    String[] candidates =
        { "2016-11-21T17:54:51.841Z",
            "2016-11-21T09:54:51.841-08:00",
            "2016", // Java8 no can do?
            "2016-11", // Java8 no can do?
            "2016-11-21", // Java8 no can do?
            "2016-11-21T01", // Java8 no can do?
            "2016-11-21T01:02", // Java8 no can do?
            "2016-11-21T01:02:03" // Java8 no can do?
        };
    DateTimeFormatter JodaDateTimeFormatter = ISODateTimeFormat.dateTimeParser();
    for (String candidate : candidates) {
      System.out.println("\ncandidate:\t\"" + candidate + "\"");
      DateTime jodaDateTime = JodaDateTimeFormatter.parseDateTime(candidate);
      System.out.println("Joda:\t" + jodaDateTime);
      try {
        OffsetDateTime java8OffsetDateTime = OffsetDateTime.parse(candidate);
        System.out.println("Java8:\t" + java8OffsetDateTime);
        long jodaMillis = jodaDateTime.getMillis();
        long javaMillis = java8OffsetDateTime.toInstant().toEpochMilli();
        System.out.printf("jodaMillis:%d %s javaMillis:%d\n",
            jodaMillis,
            (jodaMillis==javaMillis) ? "==" : "!=",
            javaMillis);
      } catch (Exception e) {
        e.printStackTrace();
      }
    }
  }
}

结果就是挑战

$ java -cp ~/work/joda-time-2.9.6/joda-time-2.9.6.jar:. Java8OffsetDateTime

candidate:  "2016-11-21T17:54:51.841Z"
Joda:   2016-11-21T09:54:51.841-08:00
Java8:  2016-11-21T17:54:51.841Z
jodaMillis:1479750891841 == javaMillis:1479750891841

candidate:  "2016-11-21T09:54:51.841-08:00"
Joda:   2016-11-21T09:54:51.841-08:00
Java8:  2016-11-21T09:54:51.841-08:00
jodaMillis:1479750891841 == javaMillis:1479750891841

candidate:  "2016"
Joda:   2016-01-01T00:00:00.000-08:00
java.time.format.DateTimeParseException: Text '2016' could not be parsed at index 4
    at java.time.format.DateTimeFormatter.parseResolved0(DateTimeFormatter.java:1947)
    at java.time.format.DateTimeFormatter.parse(DateTimeFormatter.java:1849)
    at java.time.OffsetDateTime.parse(OffsetDateTime.java:402)
    at java.time.OffsetDateTime.parse(OffsetDateTime.java:387)
    at Java8OffsetDateTime.main(Java8OffsetDateTime.java:26)

candidate:  "2016-11"
Joda:   2016-11-01T00:00:00.000-07:00
java.time.format.DateTimeParseException: Text '2016-11' could not be parsed at index 7
    at java.time.format.DateTimeFormatter.parseResolved0(DateTimeFormatter.java:1947)
    at java.time.format.DateTimeFormatter.parse(DateTimeFormatter.java:1849)
    at java.time.OffsetDateTime.parse(OffsetDateTime.java:402)
    at java.time.OffsetDateTime.parse(OffsetDateTime.java:387)
    at Java8OffsetDateTime.main(Java8OffsetDateTime.java:26)

candidate:  "2016-11-21"
Joda:   2016-11-21T00:00:00.000-08:00
java.time.format.DateTimeParseException: Text '2016-11-21' could not be parsed at index 10
    at java.time.format.DateTimeFormatter.parseResolved0(DateTimeFormatter.java:1947)
    at java.time.format.DateTimeFormatter.parse(DateTimeFormatter.java:1849)
    at java.time.OffsetDateTime.parse(OffsetDateTime.java:402)
    at java.time.OffsetDateTime.parse(OffsetDateTime.java:387)
    at Java8OffsetDateTime.main(Java8OffsetDateTime.java:26)

candidate:  "2016-11-21T01"
Joda:   2016-11-21T01:00:00.000-08:00
java.time.format.DateTimeParseException: Text '2016-11-21T01' could not be parsed at index 13
    at java.time.format.DateTimeFormatter.parseResolved0(DateTimeFormatter.java:1947)
    at java.time.format.DateTimeFormatter.parse(DateTimeFormatter.java:1849)
    at java.time.OffsetDateTime.parse(OffsetDateTime.java:402)
    at java.time.OffsetDateTime.parse(OffsetDateTime.java:387)
    at Java8OffsetDateTime.main(Java8OffsetDateTime.java:26)

candidate:  "2016-11-21T01:02"
Joda:   2016-11-21T01:02:00.000-08:00
java.time.format.DateTimeParseException: Text '2016-11-21T01:02' could not be parsed at index 16
    at java.time.format.DateTimeFormatter.parseResolved0(DateTimeFormatter.java:1947)
    at java.time.format.DateTimeFormatter.parse(DateTimeFormatter.java:1849)
    at java.time.OffsetDateTime.parse(OffsetDateTime.java:402)
    at java.time.OffsetDateTime.parse(OffsetDateTime.java:387)
    at Java8OffsetDateTime.main(Java8OffsetDateTime.java:26)

candidate:  "2016-11-21T01:02:03"
Joda:   2016-11-21T01:02:03.000-08:00
java.time.format.DateTimeParseException: Text '2016-11-21T01:02:03' could not be parsed at index 19
    at java.time.format.DateTimeFormatter.parseResolved0(DateTimeFormatter.java:1947)
    at java.time.format.DateTimeFormatter.parse(DateTimeFormatter.java:1849)
    at java.time.OffsetDateTime.parse(OffsetDateTime.java:402)
    at java.time.OffsetDateTime.parse(OffsetDateTime.java:387)
    at Java8OffsetDateTime.main(Java8OffsetDateTime.java:26)

如何从“Java8不行”中去掉那些
java.time.format.DateTimeParseException
s？“案例？
这将解析您的所有日期，除了有点时髦的2016-11-21T01。如果确实需要，请查看
DateTimeFormatterBuilder
构造
ISO\u-TIME
格式化程序的方式。它使用可选的秒字段。复制它并使分钟字段也成为可选字段

DateTimeFormatter isoDateParser = new DateTimeFormatterBuilder()
        .parseCaseInsensitive()
        .append(DateTimeFormatter.ISO_LOCAL_DATE)
        .optionalStart()
        .appendLiteral('T')
        .append(DateTimeFormatter.ISO_TIME)
        .toFormatter();

感谢@Tunaki提出了替代语法。这将帮助您解析您提供的输入值。相应地调整

OffsetDateTime java8OffsetDateTime = OffsetDateTime.parse(candidate, offsetDateTimeFormatter );

DateTimeFormatter customOffsetDateTimeFormatter = new DateTimeFormatterBuilder().appendPattern("yyyy[-MM][-dd['T'HH[:mm[:ss]]]][.SSSXXX]")
            .parseDefaulting(ChronoField.MONTH_OF_YEAR, 1)
            .parseDefaulting(ChronoField.DAY_OF_MONTH, 1)
            .parseDefaulting(ChronoField.HOUR_OF_DAY, 0)
            .parseDefaulting(ChronoField.MINUTE_OF_HOUR, 0)
            .parseDefaulting(ChronoField.SECOND_OF_MINUTE, 0)
            .parseDefaulting(ChronoField.NANO_OF_SECOND, 0)
            .parseDefaulting(ChronoField.OFFSET_SECONDS, ZoneOffset.of("-08:00").getTotalSeconds())
            .toFormatter();

测试用例：（-06:00偏移量）

输出：（-06:00偏移量）

DateTimeFormatter
是您的类。然而，需要一些时间来适应这个新的java.time包。我使用它，过了一段时间，我发现它非常灵活和强大。我写了一篇小文章，描述了如何尝试将未知格式的字符串解析为日期的一般想法。以下是链接：
对于可选部件，使用
[…]
语法将更简洁。看起来像是
yyyy-MM-dd['T'HH[：MM[：ss]]][.SSSVV]
Hmmm.
java.time.format.DateTimeParseException:Text'2016-11-21'在我试图通过此发送“2016-11-21”时无法在索引10处解析。我获取这个构建器中的DateTimeFormatter，并将其交给
OffsetDateTime.parse（候选者，dtFmt），不是吗？我和你说的完全一样。在这里很好用。将测试用例添加回答案。@Veeram是的……我做错了什么。即使如此，在Java8中，如果没有大的backflip，我的用例看起来也不受支持。谢谢你的回复。我要再玩一些。也许乔达一开始帮了我太多place@Veeram您的DateTimeFormatterBuilder非常接近，但是对于通过的候选对象，除了第一个候选对象外，Java8 millis与Joda millis都不匹配（问题已经重新构造以显示这一点）。如果我能找出为什么你的格式生成器在这个案子上挣扎<代码>候选人：“2016-11-21T09:54:51.841-08:00”Joda:2016-11-21T09:54:51.841-08:00 Java8:2016-11-21T09:54:51.841Z jodaMillis:1479750891841！=javaMillis:1479722091841
我想我们赢了！“
DateTimeFormatter
…需要一些时间来适应…”更真实的话还没有说出来。DateTimeFormatter是关键。
import java.time.OffsetDateTime;
import java.time.format.DateTimeFormatter;
import java.time.format.DateTimeFormatterBuilder;
import java.time.temporal.ChronoField;
public class App 
 {
    public static void main(String[] args) {
        String[] candidates =
            {"2016-11-21T15:54:51.841Z",
                 "2016-11-21T09:54:51.841-06:00",
                    "2016", // Java8 no can do?
                    "2016-11", // Java8 no can do?
                    "2016-11-21", // Java8 no can do?
                    "2016-11-21T01", // Java8 no can do?
                    "2016-11-21T01:02", // Java8 no can do?
                    "2016-11-21T01:02:03" // Java8 no can do?*/
            };

        DateTimeFormatter customOffsetDateTimeFormatter = new DateTimeFormatterBuilder().appendPattern("yyyy[-MM][-dd['T'HH[:mm[:ss]]]][.SSSXXX]")
            .parseDefaulting(ChronoField.MONTH_OF_YEAR, 1)
            .parseDefaulting(ChronoField.DAY_OF_MONTH, 1)
            .parseDefaulting(ChronoField.HOUR_OF_DAY, 0)
            .parseDefaulting(ChronoField.MINUTE_OF_HOUR, 0)
            .parseDefaulting(ChronoField.SECOND_OF_MINUTE, 0)
            .parseDefaulting(ChronoField.NANO_OF_SECOND, 0)
            .parseDefaulting(ChronoField.OFFSET_SECONDS, ZoneOffset.of("-06:00").getTotalSeconds())
            .toFormatter();

    org.joda.time.format.DateTimeFormatter jodaDateTimeFormatter = ISODateTimeFormat.dateTimeParser();
    for (String candidate : candidates) {
        System.out.println("\ncandidate:\t\"" + candidate + "\"");
        DateTime jodaDateTime = jodaDateTimeFormatter.parseDateTime(candidate);
        System.out.println("Joda:\t" + jodaDateTime);
        try {
            OffsetDateTime java8OffsetDateTime = OffsetDateTime.parse(candidate,customOffsetDateTimeFormatter);
            System.out.println("Java8:\t" + java8OffsetDateTime);
            long jodaMillis = jodaDateTime.getMillis();
            long javaMillis = java8OffsetDateTime.toInstant().toEpochMilli();
            System.out.printf("jodaMillis:%d %s javaMillis:%d\n",
                    jodaMillis,
                    (jodaMillis == javaMillis) ? "==" : "!=",
                    javaMillis);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}  

    candidate:  "2016-11-21T15:54:51.841Z"
    Joda:   2016-11-21T09:54:51.841-06:00
    Java8:  2016-11-21T15:54:51.841Z
    jodaMillis:1479743691841 == javaMillis:1479743691841

    candidate:  "2016-11-21T09:54:51.841-06:00"
    Joda:   2016-11-21T09:54:51.841-06:00
    Java8:  2016-11-21T09:54:51.841-06:00
    jodaMillis:1479743691841 == javaMillis:1479743691841

    candidate:  "2016"
    Joda:   2016-01-01T00:00:00.000-06:00
    Java8:  2016-01-01T00:00-06:00
    jodaMillis:1451628000000 == javaMillis:1451628000000

    candidate:  "2016-11"
    Joda:   2016-11-01T00:00:00.000-05:00
    Java8:  2016-11-01T00:00-06:00
    jodaMillis:1477976400000 != javaMillis:1477980000000

    candidate:  "2016-11-21"
    Joda:   2016-11-21T00:00:00.000-06:00
    Java8:  2016-11-21T00:00-06:00
    jodaMillis:1479708000000 == javaMillis:1479708000000

    candidate:  "2016-11-21T01"
    Joda:   2016-11-21T01:00:00.000-06:00
    Java8:  2016-11-21T01:00-06:00
    jodaMillis:1479711600000 == javaMillis:1479711600000

    candidate:  "2016-11-21T01:02"
    Joda:   2016-11-21T01:02:00.000-06:00
    Java8:  2016-11-21T01:02-06:00
    jodaMillis:1479711720000 == javaMillis:1479711720000

    candidate:  "2016-11-21T01:02:03"
    Joda:   2016-11-21T01:02:03.000-06:00
    Java8:  2016-11-21T01:02:03-06:00
    jodaMillis:1479711723000 == javaMillis:1479711723000