java 验证日期 - Bean 验证注释 - 具有特定格式
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Validating Date - Bean validation annotation - With a specific format
提问by Kevin Rave
I would like to validate a Date for the format YYYY-MM-DD_hh:mm:ss
我想验证格式的日期 YYYY-MM-DD_hh:mm:ss
@Past //validates for a date that is present or past. But what are the formats it accepts
If thats not possible, I would like to use @Pattern. But what is the regexfor the above format to use in @Pattern?
如果那不可能，我想使用@Pattern. 但是regex上面的格式用于@Pattern什么？
回答by Gunnar
@Pastsupports only Dateand Calendarbut not Strings, so there is no notion of a date format.
@Past仅支持Date和Calendar而不是字符串，所以没有一个日期格式的概念。
You could create a custom constraint such as @DateFormatwhich ensures that a given string adheres to a given date format, with a constraint implementation like this:
您可以创建一个自定义约束，例如@DateFormat确保给定的字符串符合给定的日期格式，具有如下约束实现：
public class DateFormatValidatorForString
implements ConstraintValidator<DateFormat, String> {
private String format;
public void initialize(DateFormat constraintAnnotation) {
format = constraintAnnotation.value();
}
public boolean isValid(
String date,
ConstraintValidatorContext constraintValidatorContext) {
if ( date == null ) {
return true;
}
DateFormat dateFormat = new SimpleDateFormat( format );
dateFormat.setLenient( false );
try {
dateFormat.parse(date);
return true;
}
catch (ParseException e) {
return false;
}
}
}
Note that the SimpleDateFormatinstance must not be stored in an instance variable of the validator class as it is not thread-safe. Alternatively you could use the FastDateFormatclass from the commons-lang project which safely can be accessed from several threads in parallel.
请注意，该SimpleDateFormat实例不能存储在验证器类的实例变量中，因为它不是线程安全的。或者，您可以使用commons-lang 项目中的FastDateFormat类，它可以从多个线程并行安全地访问。
If you wanted to add support for Strings to @Pastyou could do so by implementing a validator implementing ConstraintValidator<Past, String>and registering using an XML constraint mapping. There would be no way to specify the expected format, though. Alternatively you could implement another custom constraint such as @PastWithFormat.
如果您想添加对字符串的支持，@Past您可以通过实现ConstraintValidator<Past, String>使用 XML约束映射实现和注册的验证器来实现。但是，没有办法指定预期的格式。或者，您可以实现另一个自定义约束，例如@PastWithFormat.
回答by Evgeniy Dorofeev
It's better to try and parse the date with SimpleDateFormat
最好尝试使用 SimpleDateFormat 解析日期
boolean isValid(String date) {
SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd'_'HH:mm:ss");
df.setLenient(false);
try {
df.parse(date);
} catch (ParseException e) {
return false;
}
return true;
}
