关于yyyy-MM-dd格式日期字符串,解析成LocalDateTime遇到的问题

yyyy-MM-dd -> LocalDateTime

直接把yyyy-MM-dd格式的日期字符串解析成LocalDateTime会抛出异常

  try {
            LocalDateTime localDateTime = LocalDateTime.parse("2019-05-27", DateTimeFormatter.ofPattern("yyyy-MM-dd"));
            System.out.println(localDateTime);
        } catch (Exception ex) {
            ex.printStackTrace();
        }

抛出如下异常

java.time.format.DateTimeParseException: Text '2019-05-27' could not be parsed: Unable to obtain LocalDateTime from TemporalAccessor: {},ISO resolved to 2019-05-27 of type java.time.format.Parsed
    at java.time.format.DateTimeFormatter.createError(DateTimeFormatter.java:1919)
    at java.time.format.DateTimeFormatter.parse(DateTimeFormatter.java:1854)
    at java.time.LocalDateTime.parse(LocalDateTime.java:492)
    at com.ahut.common.utils.DateTest.testLocalDate(DateTest.java:28)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:483)
    at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)
    at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
    at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
    at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
    at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:78)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:57)
    at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
    at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
    at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
    at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
    at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
    at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
    at org.junit.runner.JUnitCore.run(JUnitCore.java:137)
    at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:68)
    at com.intellij.rt.execution.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:47)
    at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:242)
    at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:70)
Caused by: java.time.DateTimeException: Unable to obtain LocalDateTime from TemporalAccessor: {},ISO resolved to 2019-05-27 of type java.time.format.Parsed
    at java.time.LocalDateTime.from(LocalDateTime.java:461)
    at java.time.LocalDateTime$$Lambda$7/762152757.queryFrom(Unknown Source)
    at java.time.format.Parsed.query(Parsed.java:226)
    at java.time.format.DateTimeFormatter.parse(DateTimeFormatter.java:1850)
    ... 24 more
Caused by: java.time.DateTimeException: Unable to obtain LocalTime from TemporalAccessor: {},ISO resolved to 2019-05-27 of type java.time.format.Parsed
    at java.time.LocalTime.from(LocalTime.java:409)
    at java.time.LocalDateTime.from(LocalDateTime.java:457)
    ... 27 more

解决办法yyyy-MM-dd -> LocalDate -> LocalDateTime

 try {
            LocalDate localDate = LocalDate.parse("2019-05-27", DateTimeFormatter.ofPattern("yyyy-MM-dd"));
            LocalDateTime localDateTime = localDate.atStartOfDay();
            System.out.println(localDateTime.format(DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss")));
        } catch (Exception ex) {
            ex.printStackTrace();
        }

输出

2019-05-27 00:00:00

LocalDate atStartOfDay方法源码

    /**
     * Combines this date with the time of midnight to create a {@code LocalDateTime}
     * at the start of this date.
     * <p>
     * This returns a {@code LocalDateTime} formed from this date at the time of
     * midnight, 00:00, at the start of this date.
     *
     * @return the local date-time of midnight at the start of this date, not null
     */
    public LocalDateTime atStartOfDay() {
        return LocalDateTime.of(this, LocalTime.MIDNIGHT);
    }

LocalTime常量

  /**
     * The minimum supported {@code LocalTime}, '00:00'.
     * This is the time of midnight at the start of the day.
     */
    public static final LocalTime MIN;
    /**
     * The maximum supported {@code LocalTime}, '23:59:59.999999999'.
     * This is the time just before midnight at the end of the day.
     */
    public static final LocalTime MAX;
    /**
     * The time of midnight at the start of the day, '00:00'.
     */
    public static final LocalTime MIDNIGHT;
    /**
     * The time of noon in the middle of the day, '12:00'.
     */
    public static final LocalTime NOON;
    /**
     * Constants for the local time of each hour.
     */
    private static final LocalTime[] HOURS = new LocalTime[24];

扩展

获取当前日期最早时间和最晚时间

 System.out.println(LocalDateTime.of(LocalDate.now(), LocalTime.MIN).format(DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss")));
        System.out.println(LocalDateTime.of(LocalDate.now(), LocalTime.MAX).format(DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss")));

2019-05-27 00:00:00
2019-05-27 23:59:59

封装解析方法

 /**
     * desc :
     * create_user : cheng
     * create_date : 2019/5/27 19:28
     */
    private LocalDateTime parseToLocalDateTime(String str, String pattern) {
        if (StringUtils.isAnyBlank(str, pattern)) {
            return null;
        }

        LocalDateTime localDateTime;
        try {
            localDateTime = LocalDateTime.parse(str, DateTimeFormatter.ofPattern(pattern));
        } catch (Exception ex) {
            ex.printStackTrace();
            LocalDate localDate = parseLocalDate(str, pattern);
            localDateTime = Objects.isNull(localDate) ? null : localDate.atStartOfDay();
        }
        return localDateTime;
    }

    /**
     * desc :
     * create_user : cheng
     * create_date : 2019/5/27 19:30
     */
    private LocalDate parseLocalDate(String str, String pattern) {
        if (StringUtils.isAnyBlank(str, pattern)) {
            return null;
        }

        LocalDate localDate = null;
        try {
            localDate = LocalDate.parse(str, DateTimeFormatter.ofPattern(pattern));
        } catch (Exception ex) {
            ex.printStackTrace();
        }
        return localDate;
    }

调用

  System.out.println("解析: " + parseToLocalDateTime("2019-05-27", "yyyy-MM-dd")
                .format(DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss")));

结果

解析: 2019-05-27 00:00:00