Beans annotated with @ConfigurationProperties can be their own validators when implementing Spring's Validator interface

fixes #255

spring-boot/src/main/java/org/springframework/boot/context/properties/ConfigurationPropertiesBindingPostProcessor.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2013 the original author or authors.
+ * Copyright 2012-2014 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.
@@ -49,8 +49,10 @@ import org.springframework.core.env.StandardEnvironment;
 import org.springframework.core.io.DefaultResourceLoader;
 import org.springframework.core.io.Resource;
 import org.springframework.core.io.ResourceLoader;
+import org.springframework.util.Assert;
 import org.springframework.util.ClassUtils;
 import org.springframework.util.StringUtils;
+import org.springframework.validation.Errors;
 import org.springframework.validation.Validator;
 import org.springframework.validation.beanvalidation.LocalValidatorFactoryBean;
 
@@ -60,6 +62,7 @@ import org.springframework.validation.beanvalidation.LocalValidatorFactoryBean;
  * 
  * @author Dave Syer
  * @author Phillip Webb
+ * @author Christian Dupuis
  */
 public class ConfigurationPropertiesBindingPostProcessor implements BeanPostProcessor,
 		BeanFactoryAware, ResourceLoaderAware, EnvironmentAware, ApplicationContextAware,
@@ -294,7 +297,7 @@ public class ConfigurationPropertiesBindingPostProcessor implements BeanPostProc
 		else {
 			factory.setPropertySources(this.propertySources);
 		}
-		factory.setValidator(this.validator);
+		factory.setValidator(determineValidator(bean));
 		// If no explicit conversion service is provided we add one so that (at least)
 		// comma-separated arrays of convertibles can be bound automatically
 		factory.setConversionService(this.conversionService == null ? getDefaultConversionService()
@@ -318,6 +321,16 @@ public class ConfigurationPropertiesBindingPostProcessor implements BeanPostProc
 		}
 	}
 
+	private Validator determineValidator(Object bean) {
+		if (ClassUtils.isAssignable(Validator.class, bean.getClass())) {
+			if (this.validator == null) {
+				return (Validator) bean;
+			}
+			return new ChainingValidator(this.validator, (Validator) bean);
+		}
+		return this.validator;
+	}
+
 	private PropertySources loadPropertySources(String[] path) {
 		MutablePropertySources propertySources = new MutablePropertySources();
 		PropertySourceLoader[] loaders = {
@@ -365,4 +378,38 @@ public class ConfigurationPropertiesBindingPostProcessor implements BeanPostProc
 
 	}
 
+	/**
+	 * {@link Validator} implementation that wraps {@link Validator} instances and chains
+	 * their execution.
+	 */
+	private static class ChainingValidator implements Validator {
+
+		private Validator[] validators;
+
+		public ChainingValidator(Validator... validators) {
+			Assert.notNull(validators, "Validators must not be null");
+			this.validators = validators;
+		}
+
+		@Override
+		public boolean supports(Class<?> clazz) {
+			for (Validator validator : this.validators) {
+				if (validator.supports(clazz)) {
+					return true;
+				}
+			}
+			return false;
+		}
+
+		@Override
+		public void validate(Object target, Errors errors) {
+			for (Validator validator : this.validators) {
+				if (validator.supports(target.getClass())) {
+					validator.validate(target, errors);
+				}
+			}
+		}
+
+	}
+
 }

spring-boot/src/test/java/org/springframework/boot/context/properties/ConfigurationPropertiesBindingPostProcessorTests.java

@@ -0,0 +1,151 @@
+/*
+ * Copyright 2012-2014 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.boot.context.properties;
+
+import javax.validation.constraints.NotNull;
+
+import org.junit.After;
+import org.junit.Test;
+import org.springframework.beans.factory.BeanCreationException;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.mock.env.MockEnvironment;
+import org.springframework.validation.BindException;
+import org.springframework.validation.Errors;
+import org.springframework.validation.ValidationUtils;
+import org.springframework.validation.Validator;
+import org.springframework.web.context.support.AnnotationConfigWebApplicationContext;
+
+import static org.junit.Assert.assertTrue;
+
+/**
+ * 
+ * Tests for {@link ConfigurationPropertiesBindingPostProcessor}.
+ * 
+ * @author Christian Dupuis
+ */
+public class ConfigurationPropertiesBindingPostProcessorTests {
+
+	private AnnotationConfigWebApplicationContext context;
+
+	@After
+	public void close() {
+		if (this.context != null) {
+			this.context.close();
+		}
+	}
+
+	@Test
+	public void testValidationWithoutJSR303() {
+		this.context = new AnnotationConfigWebApplicationContext();
+		this.context.register(TestConfigurationWithoutJSR303.class);
+		try {
+			this.context.refresh();
+		}
+		catch (BeanCreationException ex) {
+			BindException bex = (BindException) ex.getRootCause();
+			assertTrue(1 == bex.getErrorCount());
+		}
+	}
+
+	@Test
+	public void testValidationWithJSR303() {
+		this.context = new AnnotationConfigWebApplicationContext();
+		this.context.register(TestConfigurationWithJSR303.class);
+		try {
+			this.context.refresh();
+		}
+		catch (BeanCreationException ex) {
+			BindException bex = (BindException) ex.getRootCause();
+			assertTrue(2 == bex.getErrorCount());
+		}
+	}
+
+	@Test
+	public void testSuccessfulValidationWithJSR303() {
+		MockEnvironment env = new MockEnvironment();
+		env.setProperty("test.foo", "123456");
+		env.setProperty("test.bar", "654321");
+		this.context = new AnnotationConfigWebApplicationContext();
+		this.context.setEnvironment(env);
+		this.context.register(TestConfigurationWithJSR303.class);
+		this.context.refresh();
+	}
+
+	@Configuration
+	@EnableConfigurationProperties
+	public static class TestConfigurationWithoutJSR303 {
+
+		@Bean
+		public PropertyWithoutJSR303 testProperties() {
+			return new PropertyWithoutJSR303();
+		}
+
+	}
+
+	@ConfigurationProperties(name = "test")
+	public static class PropertyWithoutJSR303 implements Validator {
+
+		private String foo;
+
+		@Override
+		public boolean supports(Class<?> clazz) {
+			return clazz.isAssignableFrom(getClass());
+		}
+
+		@Override
+		public void validate(Object target, Errors errors) {
+			ValidationUtils.rejectIfEmpty(errors, "foo", "TEST1");
+		}
+
+		public String getFoo() {
+			return this.foo;
+		}
+
+		public void setFoo(String foo) {
+			this.foo = foo;
+		}
+
+	}
+
+	@Configuration
+	@EnableConfigurationProperties
+	public static class TestConfigurationWithJSR303 {
+
+		@Bean
+		public PropertyWithJSR303 testProperties() {
+			return new PropertyWithJSR303();
+		}
+
+	}
+
+	@ConfigurationProperties(name = "test")
+	public static class PropertyWithJSR303 extends PropertyWithoutJSR303 {
+
+		@NotNull
+		private String bar;
+
+		public void setBar(String bar) {
+			this.bar = bar;
+		}
+
+		public String getBar() {
+			return this.bar;
+		}
+	}
+
+}