为您现场使用自定义的约束。例如,将使用注释@StringField
。
@Target(ElementType.FIELD)
@Constraint(validatedBy = StringFieldValidator.class)
@Retention(RetentionPolicy.RUNTIME)
public @interface StringField {
String message() default "Wrong data of string field";
String messageNotEmpty() default "Field can't be empty";
String messageLength() default "Wrong length of field";
boolean notEmpty() default false;
int min() default 0;
int max() default Integer.MAX_VALUE;
Class<?>[] groups() default {};
Class<?>[] payload() default {};
}
然后在StringFieldValidator
类中做一些逻辑。这个类通过接口ConstraintValidator <A extends Annotation, T>
实现。
public class StringFieldValidator implements ConstraintValidator<StringField, String> {
private Boolean notEmpty;
private Integer min;
private Integer max;
private String messageNotEmpty;
private String messageLength;
@Override
public void initialize(StringField field) {
notEmpty = field.notEmpty();
min = field.min();
max = field.max();
messageNotBlank = field.messageNotEmpty();
messageLength = field.messageLength();
}
@Override
public boolean isValid(String value, ConstraintValidatorContext context) {
context.disableDefaultConstraintViolation();
if (notEmpty && value.isEmpty()) {
context.buildConstraintViolationWithTemplate(messageNotEmpty).addConstraintViolation();
return false;
}
if ((min > 0 || max < Integer.MAX_VALUE) && (value.length() < min || value.length() > max)) {
context.buildConstraintViolationWithTemplate(messageLength).addConstraintViolation();
return false;
}
return true;
}
}
然后你可以使用注解,如:
@StringField(notEmpty = true, min = 6, max = 64,
messageNotEmpty = "Field can't be empty",
messageLength = "Field should be 6 to 64 characters size")
而且毕竟,你必须在正确的顺序中仅显示一个错误消息。
为什么?用户应该知道所有的要求。 – Bozho
邑,但我只想知道它是否可能:) – Kevin