Introduced OptionalValidatorFactoryBean for scenarios where the JSR-303 API is present but no Bean Validation Provider is available (used by the MVC namespace)

Issue: SPR-11272

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

@@ -45,6 +45,7 @@ import org.springframework.context.MessageSource;
 import org.springframework.core.DefaultParameterNameDiscoverer;
 import org.springframework.core.ParameterNameDiscoverer;
 import org.springframework.core.io.Resource;
+import org.springframework.util.Assert;
 import org.springframework.util.ClassUtils;
 import org.springframework.util.CollectionUtils;
 import org.springframework.util.ReflectionUtils;
@@ -84,6 +85,7 @@ import org.springframework.util.ReflectionUtils;
 public class LocalValidatorFactoryBean extends SpringValidatorAdapter
 		implements ValidatorFactory, ApplicationContextAware, InitializingBean, DisposableBean {
 
+	// Bean Validation 1.1 close() method available?
 	private static final Method closeMethod = ClassUtils.getMethodIfAvailable(ValidatorFactory.class, "close");
 
 
@@ -214,10 +216,9 @@ public class LocalValidatorFactoryBean extends SpringValidatorAdapter
 
 
 	@Override
-	@SuppressWarnings("unchecked")
 	public void afterPropertiesSet() {
-		@SuppressWarnings("rawtypes")
-		Configuration configuration = (this.providerClass != null ?
+		@SuppressWarnings({"rawtypes", "unchecked"})
+		Configuration<?> configuration = (this.providerClass != null ?
 				Validation.byProvider(this.providerClass).configure() :
 				Validation.byDefaultProvider().configure());
 
@@ -240,7 +241,9 @@ public class LocalValidatorFactoryBean extends SpringValidatorAdapter
 			configuration.constraintValidatorFactory(targetConstraintValidatorFactory);
 		}
 
-		configureParameterNameProviderIfPossible(configuration);
+		if (this.parameterNameDiscoverer != null) {
+			configureParameterNameProviderIfPossible(configuration);
+		}
 
 		if (this.mappingLocations != null) {
 			for (Resource location : this.mappingLocations) {
@@ -329,31 +332,36 @@ public class LocalValidatorFactoryBean extends SpringValidatorAdapter
 
 	@Override
 	public Validator getValidator() {
+		Assert.notNull(this.validatorFactory, "No target ValidatorFactory set");
 		return this.validatorFactory.getValidator();
 	}
 
 	@Override
 	public ValidatorContext usingContext() {
+		Assert.notNull(this.validatorFactory, "No target ValidatorFactory set");
 		return this.validatorFactory.usingContext();
 	}
 
 	@Override
 	public MessageInterpolator getMessageInterpolator() {
+		Assert.notNull(this.validatorFactory, "No target ValidatorFactory set");
 		return this.validatorFactory.getMessageInterpolator();
 	}
 
 	@Override
 	public TraversableResolver getTraversableResolver() {
+		Assert.notNull(this.validatorFactory, "No target ValidatorFactory set");
 		return this.validatorFactory.getTraversableResolver();
 	}
 
 	@Override
 	public ConstraintValidatorFactory getConstraintValidatorFactory() {
+		Assert.notNull(this.validatorFactory, "No target ValidatorFactory set");
 		return this.validatorFactory.getConstraintValidatorFactory();
 	}
 
 	public void close() {
-		if (closeMethod != null) {
+		if (closeMethod != null && this.validatorFactory != null) {
 			ReflectionUtils.invokeMethod(closeMethod, this.validatorFactory);
 		}
 	}

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

@@ -0,0 +1,47 @@
+/*
+ * Copyright 2002-2013 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.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.validation.beanvalidation;
+
+import javax.validation.ValidationException;
+
+import org.apache.commons.logging.LogFactory;
+
+/**
+ * {@link LocalValidatorFactoryBean} subclass that simply turns
+ * {@link org.springframework.validation.Validator} calls into no-ops
+ * in case of no Bean Validation provider being available.
+ *
+ * <p>This is the actual class used by Spring's MVC configuration namespace,
+ * in case of the {@code javax.validation} API being present but no explicit
+ * Validator having been configured.
+ *
+ * @author Juergen Hoeller
+ * @since 4.0.1
+ */
+public class OptionalValidatorFactoryBean extends LocalValidatorFactoryBean {
+
+	@Override
+	public void afterPropertiesSet() {
+		try {
+			super.afterPropertiesSet();
+		}
+		catch (ValidationException ex) {
+			LogFactory.getLog(getClass()).debug("Failed to set up a Bean Validation provider", ex);
+		}
+	}
+
+}

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

@@ -83,27 +83,31 @@ public class SpringValidatorAdapter implements SmartValidator, javax.validation.
 
 	@Override
 	public boolean supports(Class<?> clazz) {
-		return true;
+		return (this.targetValidator != null);
 	}
 
 	@Override
 	public void validate(Object target, Errors errors) {
-		processConstraintViolations(this.targetValidator.validate(target), errors);
+		if (this.targetValidator != null) {
+			processConstraintViolations(this.targetValidator.validate(target), errors);
+		}
 	}
 
 	@Override
 	@SuppressWarnings("rawtypes")
 	public void validate(Object target, Errors errors, Object... validationHints) {
-		Set<Class> groups = new LinkedHashSet<Class>();
-		if (validationHints != null) {
-			for (Object hint : validationHints) {
-				if (hint instanceof Class) {
-					groups.add((Class) hint);
+		if (this.targetValidator != null) {
+			Set<Class> groups = new LinkedHashSet<Class>();
+			if (validationHints != null) {
+				for (Object hint : validationHints) {
+					if (hint instanceof Class) {
+						groups.add((Class) hint);
+					}
 				}
 			}
+			processConstraintViolations(
+					this.targetValidator.validate(target, groups.toArray(new Class[groups.size()])), errors);
 		}
-		processConstraintViolations(
-				this.targetValidator.validate(target, groups.toArray(new Class[groups.size()])), errors);
 	}
 
 	/**
@@ -200,11 +204,13 @@ public class SpringValidatorAdapter implements SmartValidator, javax.validation.
 
 	@Override
 	public <T> Set<ConstraintViolation<T>> validate(T object, Class<?>... groups) {
+		Assert.notNull(this.targetValidator, "No target Validator set");
 		return this.targetValidator.validate(object, groups);
 	}
 
 	@Override
 	public <T> Set<ConstraintViolation<T>> validateProperty(T object, String propertyName, Class<?>... groups) {
+		Assert.notNull(this.targetValidator, "No target Validator set");
 		return this.targetValidator.validateProperty(object, propertyName, groups);
 	}
 
@@ -212,16 +218,19 @@ public class SpringValidatorAdapter implements SmartValidator, javax.validation.
 	public <T> Set<ConstraintViolation<T>> validateValue(
 			Class<T> beanType, String propertyName, Object value, Class<?>... groups) {
 
+		Assert.notNull(this.targetValidator, "No target Validator set");
 		return this.targetValidator.validateValue(beanType, propertyName, value, groups);
 	}
 
 	@Override
 	public BeanDescriptor getConstraintsForClass(Class<?> clazz) {
+		Assert.notNull(this.targetValidator, "No target Validator set");
 		return this.targetValidator.getConstraintsForClass(clazz);
 	}
 
 	@Override
 	public <T> T unwrap(Class<T> type) {
+		Assert.notNull(this.targetValidator, "No target Validator set");
 		return this.targetValidator.unwrap(type);
 	}