iso日時変換処理

import java.time.OffsetDateTime;
import java.time.format.DateTimeFormatter;
import java.time.format.DateTimeFormatterBuilder;
import java.time.format.DateTimeParseException;
import java.util.Locale;

public class DateTimeConversionUtil {

    private static final DateTimeFormatter FORMATTER = new DateTimeFormatterBuilder()
        .appendOptional(DateTimeFormatter.ofPattern("yyyy-MM-dd'T'HH:mm:ss[.SSSSSS]"))
        .appendOptional(DateTimeFormatter.ofPattern("yyyy-MM-dd'T'HH:mm:ss"))
        .appendOptional(DateTimeFormatter.ofPattern("yyyyMMdd'T'HHmmss[.SSSSSS]"))
        .appendOptional(DateTimeFormatter.ofPattern("yyyyMMdd'T'HHmmss"))
        .optionalStart().appendOffset("+HHMM", "Z").optionalEnd()
        .optionalStart().appendOffset("+HH:MM", "Z").optionalEnd()
        .optionalStart().appendOffset("+HH", "Z").optionalEnd()
        .toFormatter(Locale.US);

public static String convertToFormattedString(String input) {
    // 特定の形式に対する前処理を実施
    String preprocessedInput = preprocessInput(input);
    try {
        ZonedDateTime parsedDate = ZonedDateTime.parse(preprocessedInput, FORMATTER);
        return parsedDate.format(DateTimeFormatter.ofPattern("yyyy-MM-dd'T'HH:mm:ss.SSSSSSXXX", Locale.US));
    } catch (Exception e) {
        System.err.println("日付の解析に失敗しました: " + preprocessedInput);
        return null;
    }
}

// 特定の形式の日時文字列を標準形式に変換する前処理ステップ
private static String preprocessInput(String input) {
    Pattern pattern = Pattern.compile("^(\\d{4})(\\d{2})(\\d{2})T(\\d{2})(\\d{2})(\\d{2})(\\.\\d+)?([Z+-]\\d{2}:?\\d{2})?$");
    Matcher matcher = pattern.matcher(input);

    if (matcher.matches()) {
        // yyyyMMdd'T'HHmmss 形式を yyyy-MM-dd'T'HH:mm:ss に変換
        String nanoSeconds = matcher.group(7) != null ? matcher.group(7) : ".000000"; // マイクロ秒を追加
        nanoSeconds = nanoSeconds.substring(0, Math.min(nanoSeconds.length(), 7)); // 最大6桁のマイクロ秒に調整
        String zone = matcher.group(8) != null ? matcher.group(8) : "+00:00"; // タイムゾーンがなければUTCを仮定
        return String.format("%s-%s-%sT%s:%s:%s%s%s", matcher.group(1), matcher.group(2), matcher.group(3), matcher.group(4), matcher.group(5), matcher.group(6), nanoSeconds, zone);
    }
    return input; // パターンに一致しない場合は入力をそのまま返す
}
public static void main(String[] args) {
    String[] testDates = {
        "2024-02-07T10:58:53",
        "20240207T105853",
        "20240207T10:58:53",
        "2024-02-07T10:58:53.744813",
        "20240207T105853.744813",
        "20240207T10:58:53.744813",
        "2024-02-07T10:58:53Z",
        "20240207T105853Z",
        "20240207T10:58:53Z",
        "2024-02-07T10:58:53.744813Z",
        "20240207T105853.744813Z",
        "20240207T10:58:53.744813Z",
        "2024-02-07T10:58:53+09",
        "2024-02-07T10:58:53+0900",
        "2024-02-07T10:58:53+09:00",
        "20240207T105853+09",
        "20240207T105853+0900",
        "20240207T105853+09:00",
        "20240207T10:58:53+09",
        "20240207T10:58:53+0900",
        "20240207T10:58:53+09:00",
        "2024-02-07T10:58:53.744813+09",
        "2024-02-07T10:58:53.744813+0900",
        "2024-02-07T10:58:53.744813+09:00",
        "20240207T105853.744813+09",
        "20240207T105853.744813+0900",
        "20240207T105853.744813+09:00",
        "20240207T10:58:53.744813+09",
        "20240207T10:58:53.744813+0900",
        "20240207T10:58:53.744813+09:00"
    };

    for (String dateStr : testDates) {
        System.out.println(convertToFormattedString(dateStr));
    }
}

}