Moment.js生成的日期格式在Java中解析抛出异常问题求助

Hey there! Let's break down exactly what's going wrong here and get your date parsing working smoothly.

The Core Issue #

Your Moment.js code outputs dates with ordinal suffixes (like 30th instead of just 30), but the SimpleDateFormat pattern you're using ("MMM dd, yyyy hh:mm:ss a") only expects plain numeric dates. The dd format can't recognize th/st/nd/rd—that's the root cause of your parse exception.

Quick Fixes & Best Practices #

First off: I'd strongly recommend using Java 8+'s java.time library instead of SimpleDateFormat—it's thread-safe, more flexible, and not outdated. But I'll cover solutions for both approaches to fit your project needs.

Solution 1: Parse Directly with Java 8+ DateTimeFormatter (Handle Ordinal Suffixes) #

We can build a custom formatter that understands those ordinal suffixes natively:

import java.time.LocalDateTime;
import java.time.format.DateTimeFormatter;
import java.time.format.DateTimeFormatterBuilder;
import java.time.temporal.ChronoField;
import java.util.HashMap;
import java.util.Locale;

public class OrdinalDateParser {
    public static void main(String[] args) {
        String momentGeneratedDate = "May 30th 2018, 11:38:58 am";
        
        // Build a formatter that recognizes ordinal day suffixes
        DateTimeFormatter formatter = new DateTimeFormatterBuilder()
                .appendPattern("MMMM ")
                // Map each day to its ordinal string (1st, 2nd, etc.)
                .appendText(ChronoField.DAY_OF_MONTH, new HashMap<>() {{
                    // Handle special case days
                    put(1, "1st");
                    put(2, "2nd");
                    put(3, "3rd");
                    put(21, "21st");
                    put(22, "22nd");
                    put(23, "23rd");
                    put(31, "31st");
                    // All other days use the "th" suffix
                    for (int i = 4; i <= 30; i++) {
                        if (i != 21 && i != 22 && i != 23) {
                            put(i, i + "th");
                        }
                    }
                }})
                .appendPattern(" yyyy, hh:mm:ss a")
                .toFormatter(Locale.US);
        
        LocalDateTime parsedDateTime = LocalDateTime.parse(momentGeneratedDate, formatter);
        System.out.println(parsedDateTime); // Output: 2018-05-30T11:38:58
    }
}

Solution 2: Strip Ordinal Suffixes First (Simpler Approach) #

If you don't want to build a custom formatter, just use regex to remove the suffixes before parsing:

Option A: For Legacy Code (Using SimpleDateFormat) #

Only use this if you're stuck on Java 7 or earlier:

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Locale;
import java.util.regex.Pattern;

public class LegacyDateFix {
    public static void main(String[] args) throws ParseException {
        String momentDate = "May 30th 2018, 11:38:58 am";
        
        // Regex to strip st/nd/rd/th from the date number
        String cleanedDate = Pattern.compile("(\\d+)(st|nd|rd|th)")
                .matcher(momentDate)
                .replaceAll("$1");
        
        // Now parse with a matching pattern
        SimpleDateFormat dateFormat = new SimpleDateFormat("MMMM dd yyyy, hh:mm:ss a", Locale.US);
        System.out.println(dateFormat.parse(cleanedDate)); // Output: Wed May 30 11:38:58 CST 2018
    }
}

Option B: Recommended (Java 8+ DateTimeFormatter) #

Clean the string first, then parse with the modern, safer API:

import java.time.LocalDateTime;
import java.time.format.DateTimeFormatter;
import java.util.Locale;
import java.util.regex.Pattern;

public class CleanDateParser {
    public static void main(String[] args) {
        String momentDate = "May 30th 2018, 11:38:58 am";
        
        // Remove ordinal suffixes from the date
        String cleanedDate = Pattern.compile("(\\d+)(st|nd|rd|th)")
                .matcher(momentDate)
                .replaceAll("$1");
        
        DateTimeFormatter formatter = DateTimeFormatter.ofPattern("MMMM dd yyyy, hh:mm:ss a", Locale.US);
        LocalDateTime parsedDateTime = LocalDateTime.parse(cleanedDate, formatter);
        System.out.println(parsedDateTime); // Output: 2018-05-30T11:38:58
    }
}

A Quick Best Practice Tip #

Avoid SimpleDateFormat whenever you can—it's not thread-safe and has a lot of hidden quirks. The java.time library (or Joda-Time for Java 7 projects) is the standard for reliable date/time operations in Java now.

内容的提问来源于stack exchange，提问作者K Guru