解决No validator could be found for constraint ‘javax.validation.constraints.NotBlank‘ validating type

痛定思痛。 2023-09-25 15:16 60阅读 0赞

#### 文章目录 ####

*  1. 复现问题
 *  2. 分析问题
 *  3. 解决问题
 *  4. 重要补充
 *  5. 其他说明

## 1. 复现问题 ##

今天在使用`Knife4j`调用后端接口，报出如下错误：

![在这里插入图片描述][5a517b85a3c44228981cd00e9b407c9e.png]

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:116)
    	at org.hibernate.validator.internal.engine.constraintvalidation.ConstraintTree.getInitializedConstraintValidator(ConstraintTree.java:162)
    	at org.hibernate.validator.internal.engine.constraintvalidation.SimpleConstraintTree.validateConstraints(SimpleConstraintTree.java:54)
    	at org.hibernate.validator.internal.engine.constraintvalidation.ConstraintTree.validateConstraints(ConstraintTree.java:75)
    	at org.hibernate.validator.internal.metadata.core.MetaConstraint.doValidateConstraint(MetaConstraint.java:130)
    	at org.hibernate.validator.internal.metadata.core.MetaConstraint.validateConstraint(MetaConstraint.java:123)
    	at org.hibernate.validator.internal.engine.ValidatorImpl.validateMetaConstraint(ValidatorImpl.java:555)
    	at org.hibernate.validator.internal.engine.ValidatorImpl.validateConstraintsForSingleDefaultGroupElement(ValidatorImpl.java:518)
    	at org.hibernate.validator.internal.engine.ValidatorImpl.validateConstraintsForDefaultGroup(ValidatorImpl.java:488)
    	at org.hibernate.validator.internal.engine.ValidatorImpl.validateConstraintsForCurrentGroup(ValidatorImpl.java:450)
    	at org.hibernate.validator.internal.engine.ValidatorImpl.validateInContext(ValidatorImpl.java:400)
    	at org.hibernate.validator.internal.engine.ValidatorImpl.validate(ValidatorImpl.java:172)
    	at org.springframework.validation.beanvalidation.SpringValidatorAdapter.validate(SpringValidatorAdapter.java:109)
    	at org.springframework.boot.autoconfigure.validation.ValidatorAdapter.validate(ValidatorAdapter.java:65)
    	at org.springframework.validation.DataBinder.validate(DataBinder.java:895)
    	at org.springframework.web.servlet.mvc.method.annotation.AbstractMessageConverterMethodArgumentResolver.validateIfApplicable(AbstractMessageConverterMethodArgumentResolver.java:245)
    	at org.springframework.web.servlet.mvc.method.annotation.RequestResponseBodyMethodProcessor.resolveArgument(RequestResponseBodyMethodProcessor.java:137)
    	at org.springframework.web.method.support.HandlerMethodArgumentResolverComposite.resolveArgument(HandlerMethodArgumentResolverComposite.java:121)
    	at org.springframework.web.method.support.InvocableHandlerMethod.getMethodArgumentValues(InvocableHandlerMethod.java:170)
    	at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:137)
    	at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:106)
    	at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:894)
    	......

即`javax.validation.UnexpectedTypeException: HV000030: No validator could be found for constraint 'javax.validation.constraints.NotBlank' validating type 'java.lang.Long'. Check configuration for 'id'`

## 2. 分析问题 ##

正赶上最近`ChatGPT`很火，于是借助`ChatGPT`来解决我的问题，如下所示：

![在这里插入图片描述][c67e5e33dc1647bead3537480bd5eff7.png]

> This means that the constraint “NotBlank” is not valid for a Long type value in the field “id”. A Long type cannot support the NotBlank constraint. You should either remove the NotBlank annotation or use another type such as a String.

芭比Q的是`ChatGPT`是英文解释，我们不妨翻译成中文，如下所示：

> 这意味着约束“NotBlank”对于字段“id”中的长整型类型值无效。Long 类型不能支持 NotBlank 约束。应删除NotBlank注解或使用其他类型（如字符串）。

从中文翻译来看，由于`id`的类型是长整型的，而`NotBlank`不能修饰长整型，如下是我的代码：

/** 
     * 自定义组件id 
     * */
    @NotBlank(message = "自定义组件id不能为空")
    @ApiModelProperty(name = "id", value = "自定义组件id", required = true, example = "1")
    private Long id;

但其给出两个解决方案：

1.  删除`NotBlank`注解
2.  使用其他数据类型（如字符串）

显然，这两种方式都无法解决我的问题。

因为`id`一般都是长整型，因而不能修改其类型，而又不能删除注解，因为必须限制`id`不能为空。

`id`不能为空，因而，我们可以考虑`不能为空`的注解，即`@notNull`。

## 3. 解决问题 ##

既然`@NotBlank`注解不能修饰长整型等，而`@NotNull`注解可以修饰长整型，因而可以进行如下修改：

/**
     * 自定义组件id
     * */
    @NotNull(message = "自定义组件id不能为空")
    @ApiModelProperty(name = "id", value = "自定义组件id", required = true, example = "1")
    private Long id;

重新启动服务后调用接口，即可成功访问，如下图所示：

![在这里插入图片描述][183dd206c3de40d8ae1cc92a84ed123a.png]

此外，`@NotBlank`注解除了不能修饰长整型，也不能修饰浮点型，布尔型等。

因为`@NotBlank`注解只能作用在`String`上，不能为`null`。而且调用`trim()`后，长度必须大于`0 ("test")` ，即必须有实际字符。

## 4. 重要补充 ##

1.  `@NotNull`注解
    
     *  不能为`null`，
     *  可以为`empty` ，比如`""`,`" "`
2.  `@NotEmpty`注解
    
     *  不能为`null`
     *  而且长度必须大于`0`，比如`" "`
     *  只能使用在字符串上

## 5. 其他说明 ##

1.  如果你对`Knife4j`比较感兴趣，可以参考这篇博文：[全网最全的Knife4j swaggerj介绍][Knife4j swaggerj]
2.  如果你对@NotEmpty、@NotBlank等注解感兴趣，可以参考这篇博文：[@NotEmpty、@NotBlank等注解的正确使用][NotEmpty_NotBlank]

[5a517b85a3c44228981cd00e9b407c9e.png]: https://img-blog.csdnimg.cn/5a517b85a3c44228981cd00e9b407c9e.png
[c67e5e33dc1647bead3537480bd5eff7.png]: https://img-blog.csdnimg.cn/c67e5e33dc1647bead3537480bd5eff7.png
[183dd206c3de40d8ae1cc92a84ed123a.png]: https://img-blog.csdnimg.cn/183dd206c3de40d8ae1cc92a84ed123a.png
[Knife4j swaggerj]: https://blog.csdn.net/lvoelife/article/details/128114264
[NotEmpty_NotBlank]: https://blog.csdn.net/lvoelife/article/details/126283828

解决No validator could be found for constraint ‘javax.validation.constraints.NotBlank‘ validating type

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