Enable logging of resolved exceptions

Previously, if an exception was resolved by a `HandlerExceptionResolver`
nothing the log indicated a failure to process the query.

This commit adds a new property `spring.mvc.log-resolved-exception` that
enables warning logs for supported `HandlerExceptionResolver` instances.

When Devtools is enabled, this flag is enabled by default.

Closes gh-2176

spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/web/WebMvcAutoConfiguration.java

@@ -68,6 +68,7 @@ import org.springframework.web.filter.HiddenHttpMethodFilter;
 import org.springframework.web.filter.HttpPutFormContentFilter;
 import org.springframework.web.filter.RequestContextFilter;
 import org.springframework.web.servlet.DispatcherServlet;
+import org.springframework.web.servlet.HandlerExceptionResolver;
 import org.springframework.web.servlet.LocaleResolver;
 import org.springframework.web.servlet.View;
 import org.springframework.web.servlet.ViewResolver;
@@ -81,6 +82,7 @@ import org.springframework.web.servlet.config.annotation.ResourceHandlerRegistry
 import org.springframework.web.servlet.config.annotation.ViewControllerRegistry;
 import org.springframework.web.servlet.config.annotation.WebMvcConfigurationSupport;
 import org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter;
+import org.springframework.web.servlet.handler.AbstractHandlerExceptionResolver;
 import org.springframework.web.servlet.handler.SimpleUrlHandlerMapping;
 import org.springframework.web.servlet.i18n.AcceptHeaderLocaleResolver;
 import org.springframework.web.servlet.i18n.FixedLocaleResolver;
@@ -415,6 +417,25 @@ public class WebMvcAutoConfiguration {
 			}
 			return super.createExceptionHandlerExceptionResolver();
 		}
+
+		@Override
+		protected void configureHandlerExceptionResolvers(
+				List<HandlerExceptionResolver> exceptionResolvers) {
+			super.configureHandlerExceptionResolvers(exceptionResolvers);
+			if (exceptionResolvers.isEmpty()) {
+				addDefaultHandlerExceptionResolvers(exceptionResolvers);
+			}
+			if (this.mvcProperties.isLogResolvedException()) {
+				for (HandlerExceptionResolver resolver : exceptionResolvers) {
+					if (resolver instanceof AbstractHandlerExceptionResolver) {
+						((AbstractHandlerExceptionResolver) resolver)
+								.setWarnLogCategory(resolver.getClass()
+										.getName());
+					}
+				}
+			}
+		}
+
 	}
 
 	@Configuration

spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/web/WebMvcProperties.java

@@ -78,6 +78,11 @@ public class WebMvcProperties {
 	 */
 	private boolean throwExceptionIfNoHandlerFound = false;
 
+	/**
+	 * Enable warn logging of exceptions resolved by a "HandlerExceptionResolver".
+	 */
+	private boolean logResolvedException = false;
+
 	/**
 	 * Maps file extensions to media types for content negotiation, e.g. yml->text/yaml.
 	 */
@@ -144,6 +149,14 @@ public class WebMvcProperties {
 		this.throwExceptionIfNoHandlerFound = throwExceptionIfNoHandlerFound;
 	}
 
+	public boolean isLogResolvedException() {
+		return this.logResolvedException;
+	}
+
+	public void setLogResolvedException(boolean logResolvedException) {
+		this.logResolvedException = logResolvedException;
+	}
+
 	public Map<String, MediaType> getMediaTypes() {
 		return this.mediaTypes;
 	}

spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/web/WebMvcAutoConfigurationTests.java

@@ -28,12 +28,14 @@ import java.util.Map;
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;
 
+import org.assertj.core.api.Condition;
 import org.joda.time.DateTime;
 import org.junit.After;
 import org.junit.Rule;
 import org.junit.Test;
 import org.junit.rules.ExpectedException;
 
+import org.springframework.beans.DirectFieldAccessor;
 import org.springframework.beans.factory.NoSuchBeanDefinitionException;
 import org.springframework.boot.autoconfigure.PropertyPlaceholderAutoConfiguration;
 import org.springframework.boot.autoconfigure.web.WebMvcAutoConfiguration.WebMvcAutoConfigurationAdapter;
@@ -58,15 +60,18 @@ import org.springframework.web.accept.ContentNegotiationManager;
 import org.springframework.web.bind.support.ConfigurableWebBindingInitializer;
 import org.springframework.web.filter.HttpPutFormContentFilter;
 import org.springframework.web.servlet.HandlerAdapter;
+import org.springframework.web.servlet.HandlerExceptionResolver;
 import org.springframework.web.servlet.HandlerMapping;
 import org.springframework.web.servlet.LocaleResolver;
 import org.springframework.web.servlet.View;
 import org.springframework.web.servlet.ViewResolver;
 import org.springframework.web.servlet.config.annotation.ResourceHandlerRegistry;
 import org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter;
+import org.springframework.web.servlet.handler.HandlerExceptionResolverComposite;
 import org.springframework.web.servlet.handler.SimpleUrlHandlerMapping;
 import org.springframework.web.servlet.i18n.AcceptHeaderLocaleResolver;
 import org.springframework.web.servlet.i18n.FixedLocaleResolver;
+import org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter;
 import org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter;
 import org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping;
 import org.springframework.web.servlet.resource.AppCacheManifestTransformer;
@@ -523,6 +528,37 @@ public class WebMvcAutoConfigurationTests {
 				.isNotInstanceOf(MyRequestMappingHandlerAdapter.class);
 	}
 
+	@Test
+	public void defaultLogResolvedException() {
+		load();
+		testLogResolvedExceptionCustomization(false);
+	}
+
+	@Test
+	public void customLogResolvedException() {
+		load("spring.mvc.log-resolved-exception:true");
+		testLogResolvedExceptionCustomization(true);
+	}
+
+	private void testLogResolvedExceptionCustomization(final boolean expected) {
+		HandlerExceptionResolver exceptionResolver = this.context.getBean(
+				HandlerExceptionResolver.class);
+		assertThat(exceptionResolver).isInstanceOf(HandlerExceptionResolverComposite.class);
+		List<HandlerExceptionResolver> delegates =
+				((HandlerExceptionResolverComposite) exceptionResolver).getExceptionResolvers();
+		for (HandlerExceptionResolver delegate : delegates) {
+			if (delegate instanceof AbstractHandlerMethodAdapter) {
+				assertThat(new DirectFieldAccessor(delegate).getPropertyValue("warnLogger"))
+						.is(new Condition<Object>() {
+							@Override
+							public boolean matches(Object value) {
+								return (expected ? value != null : value == null);
+							}
+						});
+			}
+		}
+	}
+
 	private void load(Class<?> config, String... environment) {
 		this.context = new AnnotationConfigEmbeddedWebApplicationContext();
 		EnvironmentTestUtils.addEnvironment(this.context, environment);

spring-boot-devtools/src/main/java/org/springframework/boot/devtools/env/DevToolsPropertyDefaultsPostProcessor.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2015 the original author or authors.
+ * Copyright 2012-2016 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.
@@ -52,6 +52,7 @@ public class DevToolsPropertyDefaultsPostProcessor implements EnvironmentPostPro
 		properties.put("spring.h2.console.enabled", "true");
 		properties.put("spring.resources.cache-period", "0");
 		properties.put("spring.template.provider.cache", "false");
+		properties.put("spring.mvc.log-resolved-exception", "true");
 		PROPERTIES = Collections.unmodifiableMap(properties);
 	}
 

spring-boot-docs/src/main/asciidoc/appendix-application-properties.adoc

@@ -338,6 +338,7 @@ content into your application; rather pick only the properties that you need.
 	spring.mvc.ignore-default-model-on-redirect=true # If the content of the "default" model should be ignored during redirect scenarios.
 	spring.mvc.locale= # Locale to use. By default, this locale is overridden by the "Accept-Language" header.
 	spring.mvc.locale-resolver=accept-header # Define how the locale should be resolved.
+	spring.mvc.log-resolved-exception=false # Enable warn logging of exceptions resolved by a "HandlerExceptionResolver".
 	spring.mvc.media-types.*= # Maps file extensions to media types for content negotiation.
 	spring.mvc.message-codes-resolver-format= # Formatting strategy for message codes. For instance `PREFIX_ERROR_CODE`.
 	spring.mvc.servlet.load-on-startup=-1 # Load on startup priority of the Spring Web Services servlet.