Question

给定下面的try / catch块，如何在实际方法范围中返回return !dateToDate.before(dateFromDate) && dateFromDate.before(dateToDate);值？它希望我回归虚假。我无法在我想要的地方包含正确的返回值，即return false当前所在的位置。

public class YourDateValidator implements ConstraintValidator<ValidDates,
        TypeToBeValidated> {

    @Override
    public void initialize(ValidDates constraintAnnotation) {

    }

    @Override
    public boolean isValid(TypeToBeValidated value, ConstraintValidatorContext context) {
        String dateTo = value.getDateTo();
        String dateFrom = value.getDateFrom();

        SimpleDateFormat formatter = new SimpleDateFormat(DateUtil.dateFormat);
        Date dateToDate = null;
        Date dateFromDate = null;
        try {
            dateFromDate = formatter.parse(dateFrom);
            dateToDate = formatter.parse(dateTo);
            return !dateToDate.before(dateFromDate) && dateFromDate.before(dateToDate);
        } catch (ParseException e) {
            e.printStackTrace();
        }

        return false;
    }

}

所需代码：

@Override
    public boolean isValid(TypeToBeValidated value, ConstraintValidatorContext context) {
        String dateTo = value.getDateTo();
        String dateFrom = value.getDateFrom();

        SimpleDateFormat formatter = new SimpleDateFormat(DateUtil.dateFormat);
        Date dateFromDate = formatter.parse(dateFrom);
        Date dateToDate = formatter.parse(dateTo);
        return !dateToDate.before(dateFromDate) && dateFromDate.before(dateToDate);
    }

我无法在@Overriden isValid类中抛出ParseException。但是我不能将返回值放在tryter的try / catch块中。我该怎么办？

Answer 1

由于您必须捕获已检查的异常，因此无法实现所需的实现。如果您的目标是只从方法中获得单个返回点，那么您可以使用在try / catch块中指定的结果变量：

@Override
public boolean isValid(TypeToBeValidated value, ConstraintValidatorContext context) {
    String dateTo = value.getDateTo();
    String dateFrom = value.getDateFrom();

    SimpleDateFormat formatter = new SimpleDateFormat(DateUtil.dateFormat);
    Date dateToDate = null;
    Date dateFromDate = null;
    boolean valid = false;
    try {
        dateFromDate = formatter.parse(dateFrom);
        dateToDate = formatter.parse(dateTo);
        valid = !dateToDate.before(dateFromDate) && dateFromDate.before(dateToDate);
    } catch (ParseException e) {
        e.printStackTrace();
    }

    return valid;
}

或者，如果您真的想在方法之外处理异常，可以将其重新抛出为未经检查的异常：

@Override
public boolean isValid(TypeToBeValidated value, ConstraintValidatorContext context) {
    String dateTo = value.getDateTo();
    String dateFrom = value.getDateFrom();

    SimpleDateFormat formatter = new SimpleDateFormat(DateUtil.dateFormat);
    Date dateToDate = null;
    Date dateFromDate = null;
    try {
        dateFromDate = formatter.parse(dateFrom);
        dateToDate = formatter.parse(dateTo);
        return !dateToDate.before(dateFromDate) && dateFromDate.before(dateToDate);
    } catch (ParseException e) {
        throw new RuntimeException(e);
    }
}

Answer 2

我建议你总是使用这样的东西：

@Override
public boolean isValid(TypeToBeValidated value, ConstraintValidatorContext context) {
    String dateTo = value.getDateTo();
    String dateFrom = value.getDateFrom();

    SimpleDateFormat formatter = new SimpleDateFormat(DateUtil.dateFormat);
    boolean isValid = false;
    try {
        Date dateFromDate = formatter.parse(dateFrom);
        Date dateToDate = formatter.parse(dateTo);
        isValid = dateFromDate.before(dateToDate);
        if( isValid ) {
            return true;
        }

        context.buildConstraintViolationWithTemplate(
                String.format("Error: dateFromDate (%s) is not before dateToDate (%s)!", 
                    dateFromDate.toString(), 
                    dateToDate.toString()
                )
            )
            .addConstraintViolation();
        }
    } catch (ParseException e) {
        context.buildConstraintViolationWithTemplate(
                String.format("Exception while validating dateFromDate (%s), dateToDate (%s)! Reason: %s", 
                    dateFromDate.toString(), 
                    dateToDate.toString(), 
                    e.getMessage()
                )
            )
            .addConstraintViolation();
    }

    return false;
}

在这种情况下，您将始终知道，为什么以及您的错位失败的数据。

无法在自定义Spring Validator中返回值

2 个答案: