Java11 (OpenJDK 11)不可解析日期

Question

我正在尝试将代码从Java 8迁移到OpenJDK 11，在我试图解析日期字符串之前，一切进展都非常顺利。我有大量这些数据字符串来自数据库(不，我不能更改数据库)，它们在Java 7中解析得很好，但在Java 11中失败。

一些注意事项：

1. 区域设置为相同的默认值。
2. 日期最初是使用具有长、长设置的日期格式化程序生成的。
3. 我在Java 8上运行了这个程序以获得磨坊的时间。然后在Java 11上，我把在磨坊的时间转换成了一个日期。看上去挺好的。
4. 然而，该系统似乎在日期和时间之间插入了一个"at“。
5. 我试图添加"at“文本到日期，但仍然失败。

有人能给我指明正确的方向吗？我最终需要对这些字符串做日期计算。

谢谢!

布鲁斯

package utility;

import java.text.DateFormat;
import java.text.ParseException;
import java.util.Date;
import java.util.Iterator;
import java.util.Locale;


public class OpenJDK11DateDisaster {
    public static void main(String args[])
    {
        /*
         * Example of the date string that works with Java 8 but fails to
         * parse in OpenJDK 11.
         * 
         * Note:  The Locale is identical between the two versions (US, English)
         * 
         */
        
        /* Java 8 Output...
        Java Version = 1.8.0_265
        Broken Date = September 1, 2015 3:13:29 AM MDT
        Convert mills to a date.
        From mills date = September 1, 2015 3:13:29 AM MDT
        Broken Date = September 1, 2015 3:13:29 AM MDT
        Attempting to parse broken date.
        Date in mills = 1441098809000
        From mills date = September 1, 2015 3:13:29 AM MDT
        
        Java 11 output...
        Java Version = 11.0.8
        Broken Date = September 1, 2015 3:13:29 AM MDT
        Convert mills to a date.
        From mills date = September 1, 2015 at 3:13:29 AM MDT
        Broken Date = September 1, 2015 3:13:29 AM MDT
        Attempting to parse broken date.
        java.text.ParseException: Unparseable date: "September 1, 2015 3:13:29 AM MDT"

        Unable to parse broken date.
        Adding in the at...
            at java.base/java.text.DateFormat.parse(DateFormat.java:395)
            at utility.OpenJDK11DateDisaster.main(OpenJDK11DateDisaster.java:60)
        Fixed date =  September 1, 2015 at 3:13:29 AM MDT
            java.text.ParseException: Unparseable date: " September 1, 2015 at 3:13:29 AM MDT"
            at java.base/java.text.DateFormat.parse(DateFormat.java:395)
            at utility.OpenJDK11DateDisaster.main(OpenJDK11DateDisaster.java:89)

        Unable to parse fixed date.

        
        */
        System.out.println("Java Version = " + System.getProperty("java.version"));
        // This is the date that will parse in Java 7 but fails in Java 11
        String BrokenDate = "September 1, 2015 3:13:29 AM MDT";
        System.out.println("Broken Date = " + BrokenDate);
        
        // Broken date converted to mills in Java 7.
        long mills = 1441098809000L;
        
            
        System.out.println("Convert mills to a date.");
        DateFormat df2 = DateFormat.getDateTimeInstance(DateFormat.LONG, DateFormat.LONG, Locale.US);
        
        Date millDate = new Date(mills);
        System.out.println("From mills date = " + df2.format(millDate));
        
        System.out.println("Broken Date = " + BrokenDate);
        
        
        /*
         * Parse these old dates.
         */
        System.out.println("Attempting to parse broken date.");
        df2 = DateFormat.getDateTimeInstance(DateFormat.LONG, DateFormat.LONG, Locale.US);
        Date date = null;
        try {
            date = df2.parse(BrokenDate) ;
        } catch (ParseException e) {
            e.printStackTrace();
            System.out.println();
            System.out.println("Unable to parse broken date.");
            
            // For some reason, they now put an "at" word between the date and the time.
            // Here we put the "at" back in and see.
            
            // See if we can fix it.
            System.out.println("Adding in the at...");
            StringList fields = Acl.split(BrokenDate, ' ');
            String FixedDate = "";
            Iterator iter = fields.iterator();
            int count = 0;
            while (iter.hasNext() ) {
                String field = (String)iter.next();
                count++;
                FixedDate += " " + field;
                if (count == 3) {
                    // add an at
                    FixedDate += " at";
                }
                
            }
            System.out.println("Fixed date = " + FixedDate);
            // Now see if it will parse
        
            try {
                date = df2.parse(FixedDate);
            } catch (ParseException e2) {
                e2.printStackTrace();
                System.out.println();
                System.out.println("Unable to parse fixed date.");
                System.exit(-1);
            }
            System.out.println("Was able to parse Fixed Date " + date);
        }
        mills = date.getTime();  // From the BrokenDate
        // Should be -62112243600000 as computed on a Java 7 machine
        System.out.println("Date in mills = " + mills);
        
        // Convert the mills to a date.
        millDate = new Date(mills);
        System.out.println("From mills date = " + df2.format(millDate));
    }
}

Answer 1

根据文档https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/text/DateFormat.html，您似乎需要完整的格式

LONG is longer, such as January 12, 1952 or 3:30:32pm
FULL is pretty completely specified, such as Tuesday, April 12, 1952 AD or 3:30:42pm PST.

如果可能的话，在解析方法(第395行)中在DateFormat.java上放置一个断点，以了解正在发生的事情。

Answer 2

一个安全的选项是将MDT替换为相应的时区说明符Mountain Standard Time。

import java.time.ZonedDateTime;
import java.time.format.DateTimeFormatter;
import java.util.Locale;

public class Main {
    public static void main(String[] args) {
        String dateTimeStr = "September 1, 2015 3:13:29 AM MDT".replace("MDT", "Mountain Standard Time");
        ZonedDateTime zdt = ZonedDateTime.parse(dateTimeStr,
                DateTimeFormatter.ofPattern("MMMM d, u h:m:s a zzzz", Locale.ENGLISH));
        System.out.println(zdt);

        // Custom format
        String formatted = zdt.format(DateTimeFormatter.ofPattern("EEEE MMMM dd uuuu 'at' hh:mm:ss a", Locale.ENGLISH));
        System.out.println(formatted);
    }
}

输出：

2015-09-01T03:13:29-06:00[America/Denver]
Tuesday September 01 2015 at 03:13:29 AM

注意：遗留的java.util日期-时间类已经过时，容易出错，它们的格式化API SimpleDateFormat也是如此。我建议您停止完全使用它们，转而使用现代日期时间API。在日期:时间上了解更多关于现代日期时间API的信息。

如果您是为您的Android项目这样做，并且您的Android级别仍然不符合Java-8，那么请检查通过desugaring提供的Java 8+ API和如何在安卓项目中使用ThreeTenABP。

带有遗留API的：

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Locale;

public class Main {
    public static void main(String[] args) throws ParseException {
        String dateTimeStr = "September 1, 2015 3:13:29 AM MDT".replace("MDT", "Mountain Standard Time");
        Date date = new SimpleDateFormat("MMMM d, yyyy h:m:s a zzzz", Locale.ENGLISH).parse(dateTimeStr);
        System.out.println(date);

        // Custom format
        String formatted = new SimpleDateFormat("EEEE MMMM dd yyyy 'at' hh:mm:ss a", Locale.ENGLISH).format(date);
        System.out.println(formatted);
    }
}