Create @EnableSpringWebSession annotation.

spring-session-core/src/main/java/org/springframework/session/EnableSpringWebSession.java

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+/*
+ * Copyright 2014-2017 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.session;
+
+import java.lang.annotation.Documented;
+import java.lang.annotation.Retention;
+import java.lang.annotation.Target;
+
+import org.springframework.context.annotation.Configuration;
+import org.springframework.context.annotation.Import;
+
+/**
+ * Add this annotation to a {@code @Configuration} class to configure a {@code WebSessionManager} for a WebFlux
+ * application. This annotation assumes a {@code ReactorSessionRepository} is defined somewhere in the application
+ * context. If not, it will fail with a clear error messages. For example:
+ *
+ * <pre>
+ * <code>
+ * {@literal @Configuration}
+ * {@literal @EnableSpringWebSession}
+ * public class SpringWebFluxConfig {
+ *
+ *     {@literal @Bean}
+ *     public ReactorSessionRepository sessionRepository() {
+ *         return new MapReactorSessionRepository();
+ *     }
+ *
+ * }
+ * </code>
+ * </pre>
+ *
+ * @author Greg Turnquist
+ * @since 2.0
+ */
+@Retention(java.lang.annotation.RetentionPolicy.RUNTIME)
+@Target({ java.lang.annotation.ElementType.TYPE })
+@Documented
+@Import(SpringWebSessionConfiguration.class)
+@Configuration
+public @interface EnableSpringWebSession {
+}

spring-session-core/src/main/java/org/springframework/session/SpringWebSessionConfiguration.java

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+/*
+ * Copyright 2014-2017 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.session;
+
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.session.web.server.session.SpringSessionWebSessionManager;
+import org.springframework.web.server.adapter.WebHttpHandlerBuilder;
+import org.springframework.web.server.session.WebSessionManager;
+
+/**
+ * Wire up a {@link WebSessionManager} using a Reactive {@link ReactorSessionRepository} from the application context.
+ * 
+ * @author Greg Turnquist
+ * @since 2.0
+ *
+ * @see EnableSpringWebSession
+ */
+@Configuration
+public class SpringWebSessionConfiguration {
+
+	/**
+	 * Configure a {@link WebSessionManager} using a provided {@link ReactorSessionRepository}.
+	 *
+	 * @param repository - a bean that implements {@link ReactorSessionRepository}.
+	 * @return a configured {@link WebSessionManager} registered with a preconfigured name.
+	 */
+	@Bean(WebHttpHandlerBuilder.WEB_SESSION_MANAGER_BEAN_NAME)
+	public WebSessionManager webSessionManager(ReactorSessionRepository<?> repository) {
+		return new SpringSessionWebSessionManager(repository);
+	}
+}

spring-session-core/src/test/java/org/springframework/session/SpringWebSessionConfigurationTests.java

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+/*
+ * Copyright 2014-2017 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.session;
+
+import org.junit.Test;
+import org.springframework.beans.factory.UnsatisfiedDependencyException;
+import org.springframework.context.annotation.AnnotationConfigApplicationContext;
+import org.springframework.context.annotation.Bean;
+import org.springframework.web.server.adapter.WebHttpHandlerBuilder;
+import org.springframework.web.server.session.WebSessionManager;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatExceptionOfType;
+
+/**
+ * Verify various configurations through {@link EnableSpringWebSession}.
+ * 
+ * @author Greg Turnquist
+ */
+public class SpringWebSessionConfigurationTests {
+
+	@Test
+	public void enableSpringWebSessionConfiguresThings() {
+
+		AnnotationConfigApplicationContext ctx = new AnnotationConfigApplicationContext();
+		ctx.register(GoodConfig.class);
+		ctx.refresh();
+
+		WebSessionManager webSessionManagerFoundByType = ctx.getBean(WebSessionManager.class);
+		Object webSessionManagerFoundByName = ctx.getBean(WebHttpHandlerBuilder.WEB_SESSION_MANAGER_BEAN_NAME);
+
+		assertThat(webSessionManagerFoundByType).isNotNull();
+		assertThat(webSessionManagerFoundByName).isNotNull();
+		assertThat(webSessionManagerFoundByType).isEqualTo(webSessionManagerFoundByName);
+
+		assertThat(ctx.getBean(ReactorSessionRepository.class)).isNotNull();
+	}
+
+	@Test
+	public void missingReactorSessionRepositoryBreaksAppContext() {
+
+		AnnotationConfigApplicationContext ctx = new AnnotationConfigApplicationContext();
+		ctx.register(BadConfig.class);
+
+		assertThatExceptionOfType(UnsatisfiedDependencyException.class)
+				.isThrownBy(ctx::refresh)
+				.withMessageContaining("Error creating bean with name 'webSessionManager'")
+				.withMessageContaining("No qualifying bean of type '" + ReactorSessionRepository.class.getCanonicalName());
+	}
+
+	/**
+	 * A configuration with all the right parts.
+	 */
+	@EnableSpringWebSession
+	static class GoodConfig {
+
+		/**
+		 * Use Reactor-friendly, {@link java.util.Map}-backed {@link ReactorSessionRepository} for test purposes.
+		 */
+		@Bean
+		ReactorSessionRepository<?> reactorSessionRepository() {
+			return new MapReactorSessionRepository();
+		}
+	}
+
+	/**
+	 * A configuration where no {@link ReactorSessionRepository} is defined. It's BAD!
+	 */
+	@EnableSpringWebSession
+	static class BadConfig {
+
+	}
+}