Java中阿拉伯语和常规日期的日期解析问题 [英] Date parsing issue with Arabic and regular date in Java

问题描述

我有一个日期转换器功能，例如:

I have a date converter function like:

public static LocalDate getLocalDateFromString(String dateString) {
    DecimalStyle defaultDecimalStyle = DateTimeFormatter.ISO_LOCAL_DATE.getDecimalStyle();
    DateTimeFormatter dateTimeFormatter = DateTimeFormatter.ISO_LOCAL_DATE.withDecimalStyle(defaultDecimalStyle.withZeroDigit('\u0660'));
    LocalDate date = LocalDate.parse(dateString, dateTimeFormatter);
    return date;
}

它对于诸如 ٢٠١٩-٠٤-١٥ 之类的阿拉伯日期也可以正常工作，但是当我传递诸如 2019-07-31 之类的正常日期时，它会抛出异常，因为格式化程序的类型不同:

It works fine for Arabic dates like ٢٠١٩-٠٤-١٥, but when I pass a normal date like 2019-07-31, it throws an exception because the formatter is of a different type:

Exception in thread "main" java.time.format.DateTimeParseException: Text '2019-07-31' could not be parsed at index 0

我无法控制传递的日期，因为它是用户传递的.

I don't have control over the date passed, as it is passed by the user.

如何使用相同的函数来解析两个日期?

How can I use the same function to parse both dates?

推荐答案

了解您的字符串

DateTimeFormatter 对您来说并不容易.我推测这种选择背后可能有一个目的:最好让您自己进入一种情况，即您事先知道要解析的字符串中使用了哪种数字，这会更好.您可能会想到:可以说服字符串源将此信息传递给您吗?

Know your string

DateTimeFormatter doesn’t make this very easy for you. I am speculating that there may be a purpose behind this choice: it’s better if you can bring yourself into a situation where you know beforehand what kind of digits is used in the string you are going to parse. You may give this a thought: could you persuade the source of your string to pass this information to you?

如果没有，当然有办法解决.以下是低级内容，但应该是一般性内容.

If not, of course there is a way through. The following is low-level but should be general.

public static LocalDate getLocalDateFromString(String dateString) {
    DateTimeFormatter dateFormatter = DateTimeFormatter.ISO_LOCAL_DATE;
    // Take a digit from dateString to determine which digits are used
    char sampleDigit = dateString.charAt(0);
    if (Character.isDigit(sampleDigit)) {
        // Subtract the numeric value of the digit to find the zero digit in the same digit block
        char zeroDigit = (char) (sampleDigit - Character.getNumericValue(sampleDigit));
        assert Character.isDigit(zeroDigit) : zeroDigit;
        assert Character.getNumericValue(zeroDigit) == 0 : zeroDigit;
        DecimalStyle defaultDecimalStyle = dateFormatter.getDecimalStyle();
        dateFormatter = dateFormatter
                .withDecimalStyle(defaultDecimalStyle.withZeroDigit(zeroDigit));
    }
    // If the examined char wasn’t a digit, the following parsing will fail;
    // but in that case the best we can give the caller is the exception from that failed parsing.
    LocalDate date = LocalDate.parse(dateString, dateFormatter);
    return date;
}

让我们尝试一下:

    System.out.println("Parsing Arabic date string to  "
            + getLocalDateFromString("٢٠١٩-٠٤-١٥"));
    System.out.println("Parsing Western date string to "
            + getLocalDateFromString("2019-07-31"));

此代码段的输出为:

Parsing Arabic date string to  2019-04-15
Parsing Western date string to 2019-07-31

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