Java 8 LocalDateTime解析无效日期 [英] Java 8 LocalDateTime is parsing invalid date

问题描述

我想在客户端验证日期，所以我写了以下代码。但是，除了获取异常之外，我正在获得一个适当的日期对象，在2月31日的日期字符串中，这显然是无效的日期。

I wanted to validate date in client side so I wrote the following code. But instead of getting an exception I am getting a proper date object for 31st of February date string, which is clearly an invalid date.

public class Test {

    public static void main(String[] args) {
        String dateFormat = "HH:mm:ss MM/dd/yyyy";
        String dateString = "11:30:59 02/31/2015";
        DateTimeFormatter dateTimeFormatter = DateTimeFormatter.ofPattern(dateFormat, Locale.US);
        try {
            LocalDateTime date = LocalDateTime.parse(dateString, dateTimeFormatter);
            System.out.println(date);
        } catch (Exception e) {
            // Throw invalid date message
        }
    }
}

输出：2015-02-28T11：30：59

Output : 2015-02-28T11:30:59

有没有人知道为什么 LocalDateTime 正在解析此日期而不是抛出异常。

Does anyone know why LocalDateTime is parsing this date instead of throwing an exception.

推荐答案

您只需要严格的 ResolverStyle 。

You just need a strict ResolverStyle.

分析文本字符串分两个阶段。阶段1是根据添加到构建器的字段的基本文本解析。阶段2将解析的字段值对解析为日期和/或时间对象。

Parsing a text string occurs in two phases. Phase 1 is a basic text parse according to the fields added to the builder. Phase 2 resolves the parsed field-value pairs into date and/or time objects. This style is used to control how phase 2, resolving, happens.

示例代码 - 其中 withResolverStyle（ResolverStyle这是重要的变化，连同使用 uuuu 而不是 yyyy （其中 uuuu 是年，yyyy是年代，因此不明确）：

Sample code - where withResolverStyle(ResolverStyle.STRICT) is the important change, along with the use of uuuu rather than yyyy (where uuuu is "year" and "yyyy" is "year of era", and therefore ambiguous):

import java.time.*;
import java.time.format.*;
import java.util.*;

public class Test {

    public static void main(String[] args) {
        String dateFormat = "HH:mm:ss MM/dd/uuuu";
        String dateString = "11:30:59 02/31/2015";
        DateTimeFormatter dateTimeFormatter = DateTimeFormatter
            .ofPattern(dateFormat, Locale.US)
            .withResolverStyle(ResolverStyle.STRICT);
        try {
            LocalDateTime date = LocalDateTime.parse(dateString, dateTimeFormatter);
            System.out.println(date);
        } catch (DateTimeParseException e) {
            // Throw invalid date message
            System.out.println("Exception was thrown");
        }
    }
}

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