注解@notBlank的工作原理

Prerequisite

add the following dependency in pom.xml:

   <dependencies>  
          <dependency>  
               <groupId>junit</groupId>  
               <artifactId>junit</artifactId>  
               <version>4.10</version>  
               <scope>test</scope>  
          </dependency>  
          <dependency>
           <groupId>org.springframework</groupId>
           <artifactId>spring-context</artifactId>
           <version>4.2.6.RELEASE</version>
           </dependency>
           <dependency>
            <groupId>org.hibernate</groupId>
            <artifactId>hibernate-validator</artifactId>
            <version>5.2.1.Final</version>
        </dependency>
        <dependency>
   <groupId>javax.el</groupId>
   <artifactId>javax.el-api</artifactId>
   <version>2.2.4</version>
</dependency>
<dependency>

I declare message attribute as NotBlank:

@NotBlank annotation is a “composite” annotation which is based on @NotNull:

And use the following code to explicitly trigger a validation:

public static void main(String[] args) {
ApplicationContext context = new ClassPathXmlApplicationContext("Beans.xml");

HelloWorld obj = (HelloWorld) context.getBean("helloWorld");
obj.setMessage(null);
    obj.printMessage();
    
    // http://*.com/questions/24386771/javax-validation-validationexception-hv000183-unable-to-load-javax-el-express
    ValidatorFactory vf = Validation.buildDefaultValidatorFactory();
Validator validator = vf.getValidator();
Set<ConstraintViolation<HelloWorld>> set = validator.validate(obj);
for (ConstraintViolation<HelloWorld> constraintViolation : set) {
System.out.println(constraintViolation.getMessage());
}
}

output:

A list of all available validator annotation

You can find a list of all available validator and their implementation from this folder:
C:\Users\i042416.m2\repository\org\hibernate\hibernate-validator\5.2.1.Final\hibernate-validator-5.2.1.Final\org\hibernate\validator\internal\constraintvalidators\bv

Debug - how does it work?

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