Lazy Validator resolution in MethodValidationPostProcessor

Closes gh-28990

spring-context/src/main/java/org/springframework/validation/beanvalidation/MethodValidationInterceptor.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2020 the original author or authors.
+ * Copyright 2002-2022 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -18,6 +18,7 @@ package org.springframework.validation.beanvalidation;
 
 import java.lang.reflect.Method;
 import java.util.Set;
+import java.util.function.Supplier;
 
 import jakarta.validation.ConstraintViolation;
 import jakarta.validation.ConstraintViolationException;
@@ -35,6 +36,7 @@ import org.springframework.core.annotation.AnnotationUtils;
 import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 import org.springframework.util.ClassUtils;
+import org.springframework.util.function.SingletonSupplier;
 import org.springframework.validation.annotation.Validated;
 
 /**
@@ -60,14 +62,14 @@ import org.springframework.validation.annotation.Validated;
  */
 public class MethodValidationInterceptor implements MethodInterceptor {
 
-	private final Validator validator;
+	private final Supplier<Validator> validator;
 
 
 	/**
 	 * Create a new MethodValidationInterceptor using a default JSR-303 validator underneath.
 	 */
 	public MethodValidationInterceptor() {
-		this(Validation.buildDefaultValidatorFactory());
+		this.validator = SingletonSupplier.of(() -> Validation.buildDefaultValidatorFactory().getValidator());
 	}
 
 	/**
@@ -75,7 +77,7 @@ public class MethodValidationInterceptor implements MethodInterceptor {
 	 * @param validatorFactory the JSR-303 ValidatorFactory to use
 	 */
 	public MethodValidationInterceptor(ValidatorFactory validatorFactory) {
-		this(validatorFactory.getValidator());
+		this.validator = SingletonSupplier.of(validatorFactory::getValidator);
 	}
 
 	/**
@@ -83,6 +85,16 @@ public class MethodValidationInterceptor implements MethodInterceptor {
 	 * @param validator the JSR-303 Validator to use
 	 */
 	public MethodValidationInterceptor(Validator validator) {
+		this.validator = () -> validator;
+	}
+
+	/**
+	 * Create a new MethodValidationInterceptor for the supplied
+	 * (potentially lazily initialized) Validator.
+	 * @param validator a Supplier for the Validator to use
+	 * @since 6.0
+	 */
+	public MethodValidationInterceptor(Supplier<Validator> validator) {
 		this.validator = validator;
 	}
 
@@ -98,7 +110,7 @@ public class MethodValidationInterceptor implements MethodInterceptor {
 		Class<?>[] groups = determineValidationGroups(invocation);
 
 		// Standard Bean Validation 1.1 API
-		ExecutableValidator execVal = this.validator.forExecutables();
+		ExecutableValidator execVal = this.validator.get().forExecutables();
 		Method methodToValidate = invocation.getMethod();
 		Set<ConstraintViolation<Object>> result;
 

spring-context/src/main/java/org/springframework/validation/beanvalidation/MethodValidationPostProcessor.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2020 the original author or authors.
+ * Copyright 2002-2022 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -17,7 +17,9 @@
 package org.springframework.validation.beanvalidation;
 
 import java.lang.annotation.Annotation;
+import java.util.function.Supplier;
 
+import jakarta.validation.Validation;
 import jakarta.validation.Validator;
 import jakarta.validation.ValidatorFactory;
 import org.aopalliance.aop.Advice;
@@ -27,9 +29,10 @@ import org.springframework.aop.framework.autoproxy.AbstractBeanFactoryAwareAdvis
 import org.springframework.aop.support.DefaultPointcutAdvisor;
 import org.springframework.aop.support.annotation.AnnotationMatchingPointcut;
 import org.springframework.beans.factory.InitializingBean;
+import org.springframework.beans.factory.ObjectProvider;
 import org.springframework.beans.factory.config.BeanPostProcessor;
-import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
+import org.springframework.util.function.SingletonSupplier;
 import org.springframework.validation.annotation.Validated;
 
 /**
@@ -62,8 +65,8 @@ public class MethodValidationPostProcessor extends AbstractBeanFactoryAwareAdvis
 
 	private Class<? extends Annotation> validatedAnnotationType = Validated.class;
 
-	@Nullable
-	private Validator validator;
+	private Supplier<Validator> validator = SingletonSupplier.of(() ->
+			Validation.buildDefaultValidatorFactory().getValidator());
 
 
 	/**
@@ -79,23 +82,6 @@ public class MethodValidationPostProcessor extends AbstractBeanFactoryAwareAdvis
 		this.validatedAnnotationType = validatedAnnotationType;
 	}
 
-	/**
-	 * Set the JSR-303 Validator to delegate to for validating methods.
-	 * <p>Default is the default ValidatorFactory's default Validator.
-	 */
-	public void setValidator(Validator validator) {
-		// Unwrap to the native Validator with forExecutables support
-		if (validator instanceof LocalValidatorFactoryBean) {
-			this.validator = ((LocalValidatorFactoryBean) validator).getValidator();
-		}
-		else if (validator instanceof SpringValidatorAdapter) {
-			this.validator = validator.unwrap(Validator.class);
-		}
-		else {
-			this.validator = validator;
-		}
-	}
-
 	/**
 	 * Set the JSR-303 ValidatorFactory to delegate to for validating methods,
 	 * using its default Validator.
@@ -103,7 +89,24 @@ public class MethodValidationPostProcessor extends AbstractBeanFactoryAwareAdvis
 	 * @see jakarta.validation.ValidatorFactory#getValidator()
 	 */
 	public void setValidatorFactory(ValidatorFactory validatorFactory) {
-		this.validator = validatorFactory.getValidator();
+		this.validator = SingletonSupplier.of(validatorFactory::getValidator);
+	}
+
+	/**
+	 * Set the JSR-303 Validator to delegate to for validating methods.
+	 * <p>Default is the default ValidatorFactory's default Validator.
+	 */
+	public void setValidator(Validator validator) {
+		this.validator = () -> validator;
+	}
+
+	/**
+	 * Set a lazily initialized Validator to delegate to for validating methods.
+	 * @since 6.0
+	 * @see #setValidator
+	 */
+	public void setValidatorProvider(ObjectProvider<Validator> validatorProvider) {
+		this.validator = validatorProvider::getObject;
 	}
 
 
@@ -116,13 +119,13 @@ public class MethodValidationPostProcessor extends AbstractBeanFactoryAwareAdvis
 	/**
 	 * Create AOP advice for method validation purposes, to be applied
 	 * with a pointcut for the specified 'validated' annotation.
-	 * @param validator the JSR-303 Validator to delegate to
+	 * @param validator a Supplier for the Validator to use
 	 * @return the interceptor to use (typically, but not necessarily,
 	 * a {@link MethodValidationInterceptor} or subclass thereof)
-	 * @since 4.2
+	 * @since 6.0
 	 */
-	protected Advice createMethodValidationAdvice(@Nullable Validator validator) {
-		return (validator != null ? new MethodValidationInterceptor(validator) : new MethodValidationInterceptor());
+	protected Advice createMethodValidationAdvice(Supplier<Validator> validator) {
+		return new MethodValidationInterceptor(validator);
 	}
 
 }