[Solved] - UnexpectedTypeException - No validator could be found for constraint

在使用休眠验证器进行Java Bean验证时，学习如何解决Java异常 UnexpectedTypeException 。

1) Problem

尝试在任何bean属性上使用 不正确的休眠验证器注释 时，将出现 UnexpectedTypeException 错误。错误堆栈跟踪看起来像这样。

Exception in thread "main" javax.validation.UnexpectedTypeException: HV000030: No validator could be found for constraint 'javax.validation.constraints.NotBlank' validating type 'java.lang.Long'. Check configuration for 'id'
	at org.hibernate.validator.internal.engine.constraintvalidation.ConstraintTree.getExceptionForNullValidator(ConstraintTree.java:108)
	at org.hibernate.validator.internal.engine.constraintvalidation.ConstraintTree.getInitializedConstraintValidator(ConstraintTree.java:140)
	at org.hibernate.validator.internal.engine.constraintvalidation.SimpleConstraintTree.validateConstraints(SimpleConstraintTree.java:55)
	at org.hibernate.validator.internal.engine.constraintvalidation.ConstraintTree.validateConstraints(ConstraintTree.java:73)
	at org.hibernate.validator.internal.metadata.core.MetaConstraint.doValidateConstraint(MetaConstraint.java:127)
	at org.hibernate.validator.internal.metadata.core.MetaConstraint.validateConstraint(MetaConstraint.java:120)
	at org.hibernate.validator.internal.engine.ValidatorImpl.validateMetaConstraint(ValidatorImpl.java:533)
	at org.hibernate.validator.internal.engine.ValidatorImpl.validateConstraintsForSingleDefaultGroupElement(ValidatorImpl.java:496)
	at org.hibernate.validator.internal.engine.ValidatorImpl.validateConstraintsForDefaultGroup(ValidatorImpl.java:465)
	at org.hibernate.validator.internal.engine.ValidatorImpl.validateConstraintsForCurrentGroup(ValidatorImpl.java:430)
	at org.hibernate.validator.internal.engine.ValidatorImpl.validateInContext(ValidatorImpl.java:380)
	at org.hibernate.validator.internal.engine.ValidatorImpl.validate(ValidatorImpl.java:169)
	at com.howtodoinjava.example.TestHibernateValidator.main(TestHibernateValidator.java:25)

例如，您收到上述错误，您尝试将 @NotBlank 批注放在任何非字符串类型的字段上，例如 java.lang.Long 类型。

public class User {
    @NotBlank			//Incorrect usage
    private Long id;
    //More fields

阅读更多： Hibernate Validator

2) Solution

如问题所述，要解决此错误，您必须使用正确的注释。在上述问题中， @NotBlank 批注必须仅应用于任何 String 字段。

要验证 long 类型字段，请使用注释 @NotNull 。

public class User {
public class User {
    @NotNull(message = "Please enter id")
    private Long id;
    @Size(max = 20, min = 3, message = "{user.name.invalid}")
    @NotEmpty(message = "Please enter name")
    private String name;
    //More fields