java 解析日期字符串抛出多个异常
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Multiple exceptions thrown parsing date string
提问by Craigy
I am trying to parse a string into a date in the constructor of an object, which we will call Example. Here is the code
我试图在对象的构造函数中将字符串解析为日期，我们将调用它Example。这是代码
private static final SimpleDateFormat sdf = new SimpleDateFormat(
"yyyy-MM-dd HH:mm:ss");
private long time;
public Example(String date) {
try {
this.time = sdf.parse(date).getTime();
} catch (Exception e) {
logger.log(Level.WARNING, "Exception while parsing date " + date, e);
}
}
Now, I am creating these objects in a Tomcat instance (whether that makes any difference or not).
现在，我在 Tomcat 实例中创建这些对象（无论是否有所不同）。
I get the following types of exceptions
我得到以下类型的异常
Fri Jul 06 15:13:48 EDT 2012 WARNING: Exception while parsing date 2012-07-06 18:57:31
java.lang.NumberFormatException: For input string: ""
at java.lang.NumberFormatException.forInputString(NumberFormatException.java:48)
at java.lang.Long.parseLong(Long.java:431)
at java.lang.Long.parseLong(Long.java:468)
at java.text.DigitList.getLong(DigitList.java:177)
at java.text.DecimalFormat.parse(DecimalFormat.java:1297)
at java.text.SimpleDateFormat.subParse(SimpleDateFormat.java:1589)
at java.text.SimpleDateFormat.parse(SimpleDateFormat.java:1311)
at java.text.DateFormat.parse(DateFormat.java:335)
at ...
Fri Jul 06 15:13:48 EDT 2012 WARNING: Exception while parsing date 2012-07-06 19:00:07
java.lang.NumberFormatException: multiple points
at sun.misc.FloatingDecimal.readJavaFormatString(FloatingDecimal.java:1082)
at java.lang.Double.parseDouble(Double.java:510)
at java.text.DigitList.getDouble(DigitList.java:151)
at java.text.DecimalFormat.parse(DecimalFormat.java:1302)
at java.text.SimpleDateFormat.subParse(SimpleDateFormat.java:1934)
at java.text.SimpleDateFormat.parse(SimpleDateFormat.java:1311)
at java.text.DateFormat.parse(DateFormat.java:335)
at ...
Fri Jul 06 15:13:48 EDT 2012 WARNING: Exception while parsing date 2012-07-06 19:13:21
java.lang.ArrayIndexOutOfBoundsException: -1
at java.text.DigitList.fitsIntoLong(DigitList.java:212)
at java.text.DecimalFormat.parse(DecimalFormat.java:1295)
at java.text.SimpleDateFormat.subParse(SimpleDateFormat.java:1934)
at java.text.SimpleDateFormat.parse(SimpleDateFormat.java:1311)
at java.text.DateFormat.parse(DateFormat.java:335)
at ...
Fri Jul 06 15:48:06 EDT 2012 WARNING: Exception while parsing last check string 2012-07-06 19:08:08
java.lang.NumberFormatException: For input string: ".200172E4.200172"
at sun.misc.FloatingDecimal.readJavaFormatString(FloatingDecimal.java:1222)
at java.lang.Double.parseDouble(Double.java:510)
at java.text.DigitList.getDouble(DigitList.java:151)
at java.text.DecimalFormat.parse(DecimalFormat.java:1302)
at java.text.SimpleDateFormat.subParse(SimpleDateFormat.java:1589)
at java.text.SimpleDateFormat.parse(SimpleDateFormat.java:1311)
at java.text.DateFormat.parse(DateFormat.java:335)
at ...
So it fails for the dates
所以它的日期失败
2012-07-06 18:57:31
2012-07-06 19:00:07
2012-07-06 19:13:21
2012-07-06 19:08:08
However, if I make a unit test I get the following values for timefrom these strings
但是，如果我进行单元测试，我会time从这些字符串中获得以下值
1341615451000
1341615607000
1341616401000
1341616088000
So the SimpleDateFormatobject does work... but not on the server? I have noticed that this issue occurs near the startup of the server, and then not later on, if that helps at all. Not really sure what to do next.
所以该SimpleDateFormat对象确实有效...但不在服务器上？我注意到这个问题发生在服务器启动附近，然后不会发生，如果这有帮助的话。不太确定接下来要做什么。
Using Tomcat 7.0 and Java 1.6 update 32.
使用 Tomcat 7.0 和 Java 1.6 更新 32。
回答by cporte
SimpleDateFormat is not thread safe, as explained https://www.palantir.com/2007/07/simpledateformat-is-not-thread-safe/Sometimes, really strange or non-logical behaviors when using "static" objects comes from concurrency issues
SimpleDateFormat 不是线程安全的，正如https://www.palantir.com/2007/07/simpledateformat-is-not-thread-safe/有时，使用“静态”对象时的真正奇怪或非逻辑行为来自并发问题
To resolve such a case, use a new instance each time (It is better than synchronizing, as synchronization can raise a bottleneck issue)
要解决这种情况，每次都使用一个新实例（这比同步要好，因为同步会引起瓶颈问题）
回答by user207421
SimpleDateFormat is not thread-safe: see the Javadoc.
SimpleDateFormat 不是线程安全的：请参阅 Javadoc。
回答by jopasserat
As of Java 8+, it might be better to prefer a java.timebased solution.
从 Java 8+ 开始，最好选择java.time基于解决方案的解决方案。
The classes in java.timeare thread safe.
中的类java.time是线程安全的。
You can achieve the equivalent date extraction like that:
您可以像这样实现等效的日期提取：
import java.time.LocalDateTime;
import java.time.format.DateTimeFormatter;
...
DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");
LocalDateTime date = LocalDateTime.parse(str, dockerDateFormatter);
and then query the fields you need from date.
然后从 中查询您需要的字段date。
More details in the JavaDoc for DateTimeFormatterand LocalDateTime.
JavaDoc 中有关DateTimeFormatter和LocalDateTime 的更多详细信息。
Another TLDR resourcewith two ready-to-use examples.
另一个TLDR 资源，包含两个现成的示例。
