Fix possible duplicate templateEngine bean in Thymeleaf auto-config

Closes gh-30384

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

@@ -0,0 +1,79 @@
+/*
+ * Copyright 2012-2022 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.
+ * You may obtain a copy of the License at
+ *
+ *      https://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.thymeleaf;
+
+import org.thymeleaf.ITemplateEngine;
+import org.thymeleaf.dialect.IDialect;
+import org.thymeleaf.spring5.ISpringTemplateEngine;
+import org.thymeleaf.spring5.ISpringWebFluxTemplateEngine;
+import org.thymeleaf.spring5.SpringTemplateEngine;
+import org.thymeleaf.spring5.SpringWebFluxTemplateEngine;
+import org.thymeleaf.templateresolver.ITemplateResolver;
+
+import org.springframework.beans.factory.ObjectProvider;
+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.condition.ConditionalOnWebApplication.Type;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+
+/**
+ * Configuration classes for Thymeleaf's {@link ITemplateEngine}. Imported by
+ * {@link ThymeleafAutoConfiguration}.
+ *
+ * @author Andy Wilkinson
+ */
+class TemplateEngineConfigurations {
+
+	@Configuration(proxyBeanMethods = false)
+	static class DefaultTemplateEngineConfiguration {
+
+		@Bean
+		@ConditionalOnMissingBean(ISpringTemplateEngine.class)
+		SpringTemplateEngine templateEngine(ThymeleafProperties properties,
+				ObjectProvider<ITemplateResolver> templateResolvers, ObjectProvider<IDialect> dialects) {
+			SpringTemplateEngine engine = new SpringTemplateEngine();
+			engine.setEnableSpringELCompiler(properties.isEnableSpringElCompiler());
+			engine.setRenderHiddenMarkersBeforeCheckboxes(properties.isRenderHiddenMarkersBeforeCheckboxes());
+			templateResolvers.orderedStream().forEach(engine::addTemplateResolver);
+			dialects.orderedStream().forEach(engine::addDialect);
+			return engine;
+		}
+
+	}
+
+	@Configuration(proxyBeanMethods = false)
+	@ConditionalOnWebApplication(type = Type.REACTIVE)
+	@ConditionalOnProperty(name = "spring.thymeleaf.enabled", matchIfMissing = true)
+	static class ReactiveTemplateEngineConfiguration {
+
+		@Bean
+		@ConditionalOnMissingBean(ISpringWebFluxTemplateEngine.class)
+		SpringWebFluxTemplateEngine templateEngine(ThymeleafProperties properties,
+				ObjectProvider<ITemplateResolver> templateResolvers, ObjectProvider<IDialect> dialects) {
+			SpringWebFluxTemplateEngine engine = new SpringWebFluxTemplateEngine();
+			engine.setEnableSpringELCompiler(properties.isEnableSpringElCompiler());
+			engine.setRenderHiddenMarkersBeforeCheckboxes(properties.isRenderHiddenMarkersBeforeCheckboxes());
+			templateResolvers.orderedStream().forEach(engine::addTemplateResolver);
+			dialects.orderedStream().forEach(engine::addDialect);
+			return engine;
+		}
+
+	}
+
+}

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2021 the original author or authors.
+ * Copyright 2012-2022 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.
@@ -24,20 +24,15 @@ import com.github.mxab.thymeleaf.extras.dataattribute.dialect.DataAttributeDiale
 import nz.net.ultraq.thymeleaf.LayoutDialect;
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
-import org.thymeleaf.dialect.IDialect;
 import org.thymeleaf.extras.java8time.dialect.Java8TimeDialect;
 import org.thymeleaf.extras.springsecurity5.dialect.SpringSecurityDialect;
-import org.thymeleaf.spring5.ISpringTemplateEngine;
 import org.thymeleaf.spring5.ISpringWebFluxTemplateEngine;
 import org.thymeleaf.spring5.SpringTemplateEngine;
-import org.thymeleaf.spring5.SpringWebFluxTemplateEngine;
 import org.thymeleaf.spring5.templateresolver.SpringResourceTemplateResolver;
 import org.thymeleaf.spring5.view.ThymeleafViewResolver;
 import org.thymeleaf.spring5.view.reactive.ThymeleafReactiveViewResolver;
 import org.thymeleaf.templatemode.TemplateMode;
-import org.thymeleaf.templateresolver.ITemplateResolver;
 
-import org.springframework.beans.factory.ObjectProvider;
 import org.springframework.boot.autoconfigure.AutoConfigureAfter;
 import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
@@ -57,6 +52,7 @@ import org.springframework.boot.web.servlet.FilterRegistrationBean;
 import org.springframework.context.ApplicationContext;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
+import org.springframework.context.annotation.Import;
 import org.springframework.core.Ordered;
 import org.springframework.security.web.server.csrf.CsrfToken;
 import org.springframework.util.MimeType;
@@ -80,6 +76,8 @@ import org.springframework.web.servlet.resource.ResourceUrlEncodingFilter;
 @EnableConfigurationProperties(ThymeleafProperties.class)
 @ConditionalOnClass({ TemplateMode.class, SpringTemplateEngine.class })
 @AutoConfigureAfter({ WebMvcAutoConfiguration.class, WebFluxAutoConfiguration.class })
+@Import({ TemplateEngineConfigurations.ReactiveTemplateEngineConfiguration.class,
+		TemplateEngineConfigurations.DefaultTemplateEngineConfiguration.class })
 public class ThymeleafAutoConfiguration {
 
 	@Configuration(proxyBeanMethods = false)
@@ -130,23 +128,6 @@ public class ThymeleafAutoConfiguration {
 
 	}
 
-	@Configuration(proxyBeanMethods = false)
-	protected static class ThymeleafDefaultConfiguration {
-
-		@Bean
-		@ConditionalOnMissingBean(ISpringTemplateEngine.class)
-		SpringTemplateEngine templateEngine(ThymeleafProperties properties,
-				ObjectProvider<ITemplateResolver> templateResolvers, ObjectProvider<IDialect> dialects) {
-			SpringTemplateEngine engine = new SpringTemplateEngine();
-			engine.setEnableSpringELCompiler(properties.isEnableSpringElCompiler());
-			engine.setRenderHiddenMarkersBeforeCheckboxes(properties.isRenderHiddenMarkersBeforeCheckboxes());
-			templateResolvers.orderedStream().forEach(engine::addTemplateResolver);
-			dialects.orderedStream().forEach(engine::addDialect);
-			return engine;
-		}
-
-	}
-
 	@Configuration(proxyBeanMethods = false)
 	@ConditionalOnWebApplication(type = Type.SERVLET)
 	@ConditionalOnProperty(name = "spring.thymeleaf.enabled", matchIfMissing = true)
@@ -199,25 +180,6 @@ public class ThymeleafAutoConfiguration {
 
 	}
 
-	@Configuration(proxyBeanMethods = false)
-	@ConditionalOnWebApplication(type = Type.REACTIVE)
-	@ConditionalOnProperty(name = "spring.thymeleaf.enabled", matchIfMissing = true)
-	static class ThymeleafReactiveConfiguration {
-
-		@Bean
-		@ConditionalOnMissingBean(ISpringWebFluxTemplateEngine.class)
-		SpringWebFluxTemplateEngine templateEngine(ThymeleafProperties properties,
-				ObjectProvider<ITemplateResolver> templateResolvers, ObjectProvider<IDialect> dialects) {
-			SpringWebFluxTemplateEngine engine = new SpringWebFluxTemplateEngine();
-			engine.setEnableSpringELCompiler(properties.isEnableSpringElCompiler());
-			engine.setRenderHiddenMarkersBeforeCheckboxes(properties.isRenderHiddenMarkersBeforeCheckboxes());
-			templateResolvers.orderedStream().forEach(engine::addTemplateResolver);
-			dialects.orderedStream().forEach(engine::addDialect);
-			return engine;
-		}
-
-	}
-
 	@Configuration(proxyBeanMethods = false)
 	@ConditionalOnWebApplication(type = Type.REACTIVE)
 	@ConditionalOnProperty(name = "spring.thymeleaf.enabled", matchIfMissing = true)