Java如何打印含时区偏移的指定格式ISO标准日期时间？

Hey there! Let's sort out this date formatting problem for you. The issue with your current code is that you're hardcoding the Z (which represents UTC time) and not properly handling the time zone offset in the format you need (-05:00). Plus, the old Date and SimpleDateFormat classes have known flaws like thread unsafety—so let's cover both modern and legacy solutions.

Recommended: Use Java 8+ Date/Time API (Modern Approach) #

Java 8 introduced a far more robust date/time API in the java.time package, built to fix the shortcomings of the old APIs. Here's how to get your desired format easily:

import java.time.ZonedDateTime;
import java.time.format.DateTimeFormatter;
import java.time.ZoneId;

public class IsoDateFormatter {
    public static void main(String[] args) {
        // Get current date/time with a specific time zone (e.g., Eastern Time, UTC-5)
        ZonedDateTime currentDateTime = ZonedDateTime.now(ZoneId.of("America/New_York"));
        
        // Define formatter for your target ISO format
        DateTimeFormatter isoFormatter = DateTimeFormatter.ofPattern("yyyy-MM-dd'T'HH:mm:ss.SSSXXX");
        
        // Format and print the result
        System.out.println(isoFormatter.format(currentDateTime));
    }
}

Quick Breakdown: #

• ZonedDateTime: Captures date/time along with time zone information, which is essential for generating the correct offset like -05:00.
• SSS: Ensures we get three digits for milliseconds (matching your 000 requirement).
• XXX: Generates the time zone offset with a colon (e.g., -05:00 or +02:00), exactly what you need.

If you want to use your system's default time zone instead, just replace ZoneId.of("America/New_York") with ZoneId.systemDefault().

Legacy Solution: Using SimpleDateFormat (For Java 7 or Older) #

If you're stuck with the old API, you can adjust your code to handle the time zone offset properly. Note that SimpleDateFormat supports the XXX format specifier starting from Java 7:

import java.util.Date;
import java.text.SimpleDateFormat;
import java.util.TimeZone;

public class LegacyIsoFormatter {
    public static void main(String[] args) {
        Date date = new Date();
        // Set the desired time zone (e.g., Eastern Time, UTC-5)
        TimeZone targetTimeZone = TimeZone.getTimeZone("America/New_York");
        
        SimpleDateFormat formatter = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss.SSSXXX");
        formatter.setTimeZone(targetTimeZone);
        
        System.out.println(formatter.format(date));
    }
}

For Java 6 or Earlier: #

If you're on an even older Java version, XXX isn't supported. You'll need a small workaround to add the colon to the offset:

import java.util.Date;
import java.text.SimpleDateFormat;
import java.util.TimeZone;

public class Java6IsoFormatter {
    public static void main(String[] args) {
        Date date = new Date();
        TimeZone targetTimeZone = TimeZone.getTimeZone("America/New_York");
        
        // Format the date/time part
        SimpleDateFormat datePartFormatter = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss.SSS");
        datePartFormatter.setTimeZone(targetTimeZone);
        String datePart = datePartFormatter.format(date);
        
        // Format the offset part and insert the colon
        SimpleDateFormat offsetFormatter = new SimpleDateFormat("Z");
        offsetFormatter.setTimeZone(targetTimeZone);
        String rawOffset = offsetFormatter.format(date);
        String formattedOffset = rawOffset.substring(0, 3) + ":" + rawOffset.substring(3);
        
        // Combine and print the final result
        System.out.println(datePart + formattedOffset);
    }
}

Whichever approach you pick, the core fix is to stop hardcoding Z and ensure your formatter properly accounts for the time zone offset using the right pattern to get the colon-separated format you need.

内容的提问来源于stack exchange，提问作者azaveri7