Date Formatting

The new version recommends using DateTimeFormatter instead of SimpleDateFormat to achieve thread safety and a clearer API. Since DateTimeFormatter.ofPattern() instantiation has certain overhead, especially for custom patterns (such as "yyyy-MM-dd HH:mm:ss"), we can optimize by caching DateTimeFormatter instances.

Formatter usage is as follows:

new Formatter(TemporalAccessor temporal).format();
new Formatter(TemporalAccessor temporal).format(String format)

The TemporalAccessor interface is implemented by common date types, so we can pass them in the constructor and then specify the date format string.

Utility Functions

Mainly utility functions for now() that return the current time as a string.

/**
 * Obtain current time by specified format.
 *
 * @param formatter The formatter object
 * @return The current time
 */
public static String now(DateTimeFormatter formatter) {
    return LocalDateTime.now().format(formatter);
}

/**
 * Obtain current time by specified format.
 *
 * @param format The format string
 * @return The current time
 */
public static String now(String format) {
    return now(Formatter.getDateFormatter(format));
}

/**
 * Obtain current time, which is formatted by default like "yyyy-MM-dd HH:mm:ss".
 *
 * @return The current time
 */
public static String now() {
    return now(Formatter.getDateTimeFormatter());
}

/**
 * Obtain current time, which is formatted like "yyyy-MM-dd HH:mm".
 *
 * @return The current time
 */
public static String nowShort() {
    return now(Formatter.getDateTimeShortFormatter());
}

/**
 * Request timestamp, format must conform to RFC1123 date format
 *
 * @return The current time
 */
public static String nowGMTDate() {
    return Formatter.GMT_FORMATTER.format(Instant.now());
}

/**
 * Request timestamp. Following ISO8601 standard representation, using UTC time, format is yyyy-MM-ddTHH:mm:ssZ
 *
 * @return The current time
 */
public static String newISO8601Date() {
    return Formatter.ISO8601_FORMATTER.format(Instant.now());
}

Additionally, there is a function for converting strings to dates, which mainly uses regular expressions to match whether the string is a date string and then performs the conversion.