Register ResourceUrlEncodingFilter only if necessary

Previously, `ResourceUrlEncodingFilter` was registered even if the
resource chain handling was disabled (which is the default).

We now take care of registering it only if the resource chain handling is
enabled.

Closes gh-3353

spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/thymeleaf/ThymeleafAutoConfiguration.java

@@ -33,6 +33,7 @@ import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean
 import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnWebApplication;
 import org.springframework.boot.autoconfigure.template.TemplateLocation;
+import org.springframework.boot.autoconfigure.web.ConditionalOnEnabledResourceChain;
 import org.springframework.boot.autoconfigure.web.WebMvcAutoConfiguration;
 import org.springframework.boot.context.properties.EnableConfigurationProperties;
 import org.springframework.context.ApplicationContext;
@@ -232,6 +233,7 @@ public class ThymeleafAutoConfiguration {
 
 		@Bean
 		@ConditionalOnMissingBean
+		@ConditionalOnEnabledResourceChain
 		public ResourceUrlEncodingFilter resourceUrlEncodingFilter() {
 			return new ResourceUrlEncodingFilter();
 		}

spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/velocity/VelocityAutoConfiguration.java

@@ -33,6 +33,7 @@ import org.springframework.boot.autoconfigure.condition.ConditionalOnNotWebAppli
 import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnWebApplication;
 import org.springframework.boot.autoconfigure.template.TemplateLocation;
+import org.springframework.boot.autoconfigure.web.ConditionalOnEnabledResourceChain;
 import org.springframework.boot.autoconfigure.web.WebMvcAutoConfiguration;
 import org.springframework.boot.context.properties.EnableConfigurationProperties;
 import org.springframework.boot.web.servlet.view.velocity.EmbeddedVelocityViewResolver;
@@ -137,6 +138,7 @@ public class VelocityAutoConfiguration {
 
 		@Bean
 		@ConditionalOnMissingBean
+		@ConditionalOnEnabledResourceChain
 		public ResourceUrlEncodingFilter resourceUrlEncodingFilter() {
 			return new ResourceUrlEncodingFilter();
 		}

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

@@ -0,0 +1,39 @@
+/*
+ * Copyright 2012-2015 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.autoconfigure.web;
+
+import java.lang.annotation.Documented;
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+import org.springframework.context.annotation.Conditional;
+
+/**
+ * {@link Conditional} that checks whether or not the Spring resource handling chain is
+ * enabled. Matches if {@link ResourceProperties.Chain#getEnabled()} is {@code true}.
+ *
+ * @author Stephane Nicoll
+ * @since 1.3.0
+ */
+@Target({ElementType.TYPE, ElementType.METHOD})
+@Retention(RetentionPolicy.RUNTIME)
+@Documented
+@Conditional(OnEnabledResourceChainCondition.class)
+public @interface ConditionalOnEnabledResourceChain {
+}

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

@@ -0,0 +1,47 @@
+/*
+ * Copyright 2012-2015 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.autoconfigure.web;
+
+import org.springframework.boot.autoconfigure.condition.ConditionOutcome;
+import org.springframework.boot.autoconfigure.condition.SpringBootCondition;
+import org.springframework.boot.bind.PropertySourcesPropertyValues;
+import org.springframework.boot.bind.RelaxedDataBinder;
+import org.springframework.context.annotation.Condition;
+import org.springframework.context.annotation.ConditionContext;
+import org.springframework.core.env.ConfigurableEnvironment;
+import org.springframework.core.type.AnnotatedTypeMetadata;
+
+/**
+ * {@link Condition} that checks whether or not the Spring resource handling chain is
+ * enabled.
+ *
+ * @author Stephane Nicoll
+ */
+class OnEnabledResourceChainCondition extends SpringBootCondition {
+
+	@Override
+	public ConditionOutcome getMatchOutcome(ConditionContext context, AnnotatedTypeMetadata metadata) {
+		ConfigurableEnvironment environment = (ConfigurableEnvironment) context.getEnvironment();
+		ResourceProperties resourceProperties = new ResourceProperties();
+		RelaxedDataBinder binder = new RelaxedDataBinder(resourceProperties, "spring.resources");
+		binder.bind(new PropertySourcesPropertyValues(environment.getPropertySources()));
+
+		Boolean match = resourceProperties.getChain().getEnabled();
+		return new ConditionOutcome(match, "Resource chain is " + (match ? "enabled" : "disabled" + ")"));
+	}
+
+}

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

@@ -173,7 +173,9 @@ public class ResourceProperties implements ResourceLoaderAware {
 		private final Strategy strategy = new Strategy();
 
 		public Boolean getEnabled() {
-			return this.enabled;
+			return Boolean.TRUE.equals(this.enabled)
+					|| getStrategy().getFixed().isEnabled()
+					|| getStrategy().getContent().isEnabled();
 		}
 
 		public void setEnabled(boolean enabled) {

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

@@ -256,9 +256,7 @@ public class WebMvcAutoConfiguration {
 
 		private void registerResourceChain(ResourceHandlerRegistration registration) {
 			ResourceProperties.Chain properties = this.resourceProperties.getChain();
-			if (Boolean.TRUE.equals(properties.getEnabled())
-					|| properties.getStrategy().getFixed().isEnabled()
-					|| properties.getStrategy().getContent().isEnabled()) {
+			if (properties.getEnabled()) {
 				configureResourceChain(properties,
 						registration.resourceChain(properties.isCache()));
 			}

spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/thymeleaf/ThymeleafAutoConfigurationTests.java

@@ -196,10 +196,20 @@ public class ThymeleafAutoConfigurationTests {
 	}
 
 	@Test
-	public void registerResourceHandlingFilter() throws Exception {
+	public void registerResourceHandlingFilterDisabledByDefault() throws Exception {
 		this.context.register(ThymeleafAutoConfiguration.class,
 				PropertyPlaceholderAutoConfiguration.class);
 		this.context.refresh();
+		assertEquals(0, this.context.getBeansOfType(ResourceUrlEncodingFilter.class).size());
+	}
+
+	@Test
+	public void registerResourceHandlingFilterOnlyIfResourceChainIsEnabled() throws Exception {
+		this.context.register(ThymeleafAutoConfiguration.class,
+				PropertyPlaceholderAutoConfiguration.class);
+		EnvironmentTestUtils.addEnvironment(this.context,
+				"spring.resources.chain.enabled:true");
+		this.context.refresh();
 		assertNotNull(this.context.getBean(ResourceUrlEncodingFilter.class));
 	}
 

spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/velocity/VelocityAutoConfigurationTests.java

@@ -49,6 +49,7 @@ import static org.hamcrest.Matchers.equalTo;
 import static org.hamcrest.Matchers.instanceOf;
 import static org.hamcrest.Matchers.is;
 import static org.hamcrest.Matchers.notNullValue;
+import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertNotNull;
 import static org.junit.Assert.assertThat;
 
@@ -56,6 +57,7 @@ import static org.junit.Assert.assertThat;
  * Tests for {@link VelocityAutoConfiguration}.
  *
  * @author Andy Wilkinson
+ * @author Stephane Nicoll
  */
 public class VelocityAutoConfigurationTests {
 
@@ -189,8 +191,14 @@ public class VelocityAutoConfigurationTests {
 	}
 
 	@Test
-	public void registerResourceHandlingFilter() throws Exception {
+	public void registerResourceHandlingFilterDisabledByDefault() throws Exception {
 		registerAndRefreshContext();
+		assertEquals(0, this.context.getBeansOfType(ResourceUrlEncodingFilter.class).size());
+	}
+
+	@Test
+	public void registerResourceHandlingFilterOnlyIfResourceChainIsEnabled() throws Exception {
+		registerAndRefreshContext("spring.resources.chain.enabled:true");
 		assertNotNull(this.context.getBean(ResourceUrlEncodingFilter.class));
 	}
 

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

@@ -0,0 +1,92 @@
+/*
+ * Copyright 2012-2015 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.autoconfigure.web;
+
+import org.junit.After;
+import org.junit.Test;
+
+import org.springframework.boot.test.EnvironmentTestUtils;
+import org.springframework.context.annotation.AnnotationConfigApplicationContext;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+
+/**
+ * Tests for {@link ConditionalOnEnabledResourceChain}.
+ *
+ * @author Stephane Nicoll
+ */
+public class ConditionalOnEnabledResourceChainTests {
+
+	private final AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext();
+
+	@After
+	public void closeContext() {
+		this.context.close();
+	}
+
+	@Test
+	public void disabledByDefault() {
+		load();
+		assertFalse(this.context.containsBean("foo"));
+	}
+
+	@Test
+	public void disabledExplicitly() {
+		load("spring.resources.chain.enabled:false");
+		assertFalse(this.context.containsBean("foo"));
+	}
+
+	@Test
+	public void enabledViaMainEnabledFlag() {
+		load("spring.resources.chain.enabled:true");
+		assertTrue(this.context.containsBean("foo"));
+	}
+
+	@Test
+	public void enabledViaFixedStrategyFlag() {
+		load("spring.resources.chain.strategy.fixed.enabled:true");
+		assertTrue(this.context.containsBean("foo"));
+	}
+
+	@Test
+	public void enabledViaContentStrategyFlag() {
+		load("spring.resources.chain.strategy.content.enabled:true");
+		assertTrue(this.context.containsBean("foo"));
+	}
+
+
+	private void load(String... environment) {
+		this.context.register(Config.class);
+		EnvironmentTestUtils.addEnvironment(this.context, environment);
+		this.context.refresh();
+	}
+
+	@Configuration
+	static class Config {
+
+		@Bean
+		@ConditionalOnEnabledResourceChain
+		public String foo() {
+			return "foo";
+		}
+
+	}
+
+}