@Bean
public BeanPostProcessor beanValidationPostProcessor() {
  return new BeanValidationPostProcessor();
}

@Bean
public UserModel getUserModel() {
  UserModel userModel = new UserModel();
  userModel.setUsername(null);
  userModel.setPassword("123");
  return userModel;
}

@Data
class UserModel {
  @NotNull(message = "username can not be null")
  @Pattern(regexp = "[a-zA-Z0-9_]{5,10}", message = "username is illegal")
  private String username;
  @Size(min = 5, max = 10, message = "password's length is illegal")
  private String password;
}

protected void doValidate(Object bean) {
 Assert.state(this.validator != null, "No Validator set");
 Set<ConstraintViolation<Object>> result = this.validator.validate(bean);

@Component
@Validated
public class BeanForMethodValidation {
  public void validate(@NotEmpty String name, @Min(10) int age) {
    System.out.println("validate, name: " + name + ", age: " + age);
  }
}

public void afterPropertiesSet() {
  Pointcut pointcut = new `AnnotationMatchingPointcut`(this.validatedAnnotationType, true);
  this.advisor = new `DefaultPointcutAdvisor`(pointcut, createMethodValidationAdvice(this.validator));
}
protected Advice createMethodValidationAdvice(@Nullable Validator validator) {
 return (validator != null ? new `MethodValidationInterceptor`(validator) : new MethodValidationInterceptor());
}

public class Person {
@NotNull(message = "性別不能為空")
private Gender gender;
@Min(10)
private Integer age;
...
}
ValidatorFactory validatorFactory = Validation.buildDefaultValidatorFactory();
Validator validator = validatorFactory.getValidator();
Person person = new Person();
person.setGender(Gender.Man);
validator.validate(person);

public Validator `getValidator`() {
 return `createValidator`(
 constraintValidatorManager.getDefaultConstraintValidatorFactory(),
 valueExtractorManager,
 validatorFactoryScopedContext,
 methodValidationConfiguration
 );
}
Validator `createValidator`(ConstraintValidatorFactory constraintValidatorFactory,
 ValueExtractorManager valueExtractorManager,
 ValidatorFactoryScopedContext validatorFactoryScopedContext,
 MethodValidationConfiguration methodValidationConfiguration) {
 
 BeanMetaDataManager beanMetaDataManager = beanMetaDataManagers.computeIfAbsent(
 new BeanMetaDataManagerKey( validatorFactoryScopedContext.getParameterNameProvider(), valueExtractorManager, methodValidationConfiguration ),
 key -> new BeanMetaDataManager(
  `constraintHelper`,
  executableHelper,
  typeResolutionHelper,
  validatorFactoryScopedContext.getParameterNameProvider(),
  valueExtractorManager,
  validationOrderGenerator,
  buildDataProviders(),
  methodValidationConfiguration
 )
 );
  
    return `new ValidatorImpl`(
  constraintValidatorFactory,
  beanMetaDataManager,
  valueExtractorManager,
  constraintValidatorManager,
  validationOrderGenerator,
  validatorFactoryScopedContext
 );
}
public final <T> Set<ConstraintViolation<T>> validate(T object, Class<?>... groups) {
 Contracts.assertNotNull( object, MESSAGES.validatedObjectMustNotBeNull() );
 sanityCheckGroups( groups );

 ValidationContext<T> validationContext = `getValidationContextBuilder().forValidate( object )`;

 if ( !validationContext.getRootBeanMetaData().hasConstraints() ) {
 return Collections.emptySet();
 }

 ValidationOrder validationOrder = determineGroupValidationOrder( groups );
 ValueContext<?, Object> valueContext = `ValueContext.getLocalExecutionContext`(
  validatorScopedContext.getParameterNameProvider(),
  object,
  validationContext.getRootBeanMetaData(),
  PathImpl.createRootPath()
 );

 return validateInContext( validationContext, valueContext, validationOrder );
}

public static <U extends Annotation> ConstraintTree<U> of(ConstraintDescriptorImpl<U> composingDescriptor, Type validatedValueType) {
 if ( composingDescriptor.getComposingConstraintImpls().isEmpty() ) {
 return new SimpleConstraintTree<>( composingDescriptor, validatedValueType );
 }
 else {
 return new ComposingConstraintTree<>( composingDescriptor, validatedValueType );
 }
}

putConstraints( tmpConstraints, DecimalMax.class, Arrays.asList(
 DecimalMaxValidatorForBigDecimal.class,
 DecimalMaxValidatorForBigInteger.class,
 DecimalMaxValidatorForDouble.class,
 DecimalMaxValidatorForFloat.class,
 DecimalMaxValidatorForLong.class,
 DecimalMaxValidatorForNumber.class,
 DecimalMaxValidatorForCharSequence.class,
 DecimalMaxValidatorForMonetaryAmount.class
) );