Clarify scope of JNDI-based MailSenderAutoConfiguration

This commit separates the auto-configuration of JavaMailSender in two
distinct configuration: one based on existing Session available on JNDI
and the other one based on properties configuration.

This clarifies the auto-configuration report and the fact that the JNDI
variant overrides any Session-related properties that would have been
set in the environment

Closes gh-13026

spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/mail/MailProperties.java

 /*
- * Copyright 2012-2015 the original author or authors.
+ * Copyright 2012-2018 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.
@@ -66,12 +66,12 @@ public class MailProperties {
 	private Charset defaultEncoding = DEFAULT_CHARSET;
 
 	/**
-	 * Additional JavaMail session properties.
+	 * Additional JavaMail Session properties.
 	 */
 	private Map<String, String> properties = new HashMap<String, String>();
 
 	/**
-	 * Session JNDI name. When set, takes precedence to others mail settings.
+	 * Session JNDI name. When set, takes precedence to others Session settings.
 	 */
 	private String jndiName;
 

spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/mail/MailSenderAutoConfiguration.java

 /*
- * Copyright 2012-2016 the original author or authors.
+ * Copyright 2012-2018 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.
@@ -16,14 +16,9 @@
 
 package org.springframework.boot.autoconfigure.mail;
 
-import java.util.Map;
-import java.util.Properties;
-
 import javax.activation.MimeType;
-import javax.mail.Session;
 import javax.mail.internet.MimeMessage;
 
-import org.springframework.beans.factory.ObjectProvider;
 import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
 import org.springframework.boot.autoconfigure.condition.AnyNestedCondition;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
@@ -31,12 +26,10 @@ import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean
 import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;
 import org.springframework.boot.autoconfigure.mail.MailSenderAutoConfiguration.MailSenderCondition;
 import org.springframework.boot.context.properties.EnableConfigurationProperties;
-import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Conditional;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.context.annotation.Import;
 import org.springframework.mail.MailSender;
-import org.springframework.mail.javamail.JavaMailSenderImpl;
 
 /**
  * {@link EnableAutoConfiguration Auto configuration} for email support.
@@ -47,60 +40,16 @@ import org.springframework.mail.javamail.JavaMailSenderImpl;
  * @since 1.2.0
  */
 @Configuration
-@ConditionalOnClass({ MimeMessage.class, MimeType.class })
+@ConditionalOnClass({ MimeMessage.class, MimeType.class, MailSender.class })
 @ConditionalOnMissingBean(MailSender.class)
 @Conditional(MailSenderCondition.class)
 @EnableConfigurationProperties(MailProperties.class)
-@Import(JndiSessionConfiguration.class)
+@Import({ MailSenderJndiConfiguration.class, MailSenderPropertiesConfiguration.class })
 public class MailSenderAutoConfiguration {
 
-	private final MailProperties properties;
-
-	private final Session session;
-
-	public MailSenderAutoConfiguration(MailProperties properties,
-			ObjectProvider<Session> session) {
-		this.properties = properties;
-		this.session = session.getIfAvailable();
-	}
-
-	@Bean
-	public JavaMailSenderImpl mailSender() {
-		JavaMailSenderImpl sender = new JavaMailSenderImpl();
-		if (this.session != null) {
-			sender.setSession(this.session);
-		}
-		else {
-			applyProperties(sender);
-		}
-		return sender;
-	}
-
-	private void applyProperties(JavaMailSenderImpl sender) {
-		sender.setHost(this.properties.getHost());
-		if (this.properties.getPort() != null) {
-			sender.setPort(this.properties.getPort());
-		}
-		sender.setUsername(this.properties.getUsername());
-		sender.setPassword(this.properties.getPassword());
-		sender.setProtocol(this.properties.getProtocol());
-		if (this.properties.getDefaultEncoding() != null) {
-			sender.setDefaultEncoding(this.properties.getDefaultEncoding().name());
-		}
-		if (!this.properties.getProperties().isEmpty()) {
-			sender.setJavaMailProperties(asProperties(this.properties.getProperties()));
-		}
-	}
-
-	private Properties asProperties(Map<String, String> source) {
-		Properties properties = new Properties();
-		properties.putAll(source);
-		return properties;
-	}
-
 	/**
-	 * Condition to trigger the creation of a {@link JavaMailSenderImpl}. This kicks in if
-	 * either the host or jndi name property is set.
+	 * Condition to trigger the creation of a {@link MailSender}. This kicks in if either
+	 * the host or jndi name property is set.
 	 */
 	static class MailSenderCondition extends AnyNestedCondition {
 

spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/mail/JndiSessionConfiguration.java → spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/mail/MailSenderJndiConfiguration.java

 /*
- * Copyright 2012-2016 the original author or authors.
+ * Copyright 2012-2018 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.
@@ -26,9 +26,11 @@ import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.jndi.JndiLocatorDelegate;
+import org.springframework.mail.MailSender;
+import org.springframework.mail.javamail.JavaMailSenderImpl;
 
 /**
- * Auto-configure a {@link Session} available on JNDI.
+ * Auto-configure a {@link MailSender} based on a {@link Session} available on JNDI.
  *
  * @author Eddú Meléndez
  * @author Stephane Nicoll
@@ -37,14 +39,22 @@ import org.springframework.jndi.JndiLocatorDelegate;
 @ConditionalOnClass(Session.class)
 @ConditionalOnProperty(prefix = "spring.mail", name = "jndi-name")
 @ConditionalOnJndi
-class JndiSessionConfiguration {
+class MailSenderJndiConfiguration {
 
 	private final MailProperties properties;
 
-	JndiSessionConfiguration(MailProperties properties) {
+	MailSenderJndiConfiguration(MailProperties properties) {
 		this.properties = properties;
 	}
 
+	@Bean
+	public JavaMailSenderImpl mailSender(Session session) {
+		JavaMailSenderImpl sender = new JavaMailSenderImpl();
+		sender.setDefaultEncoding(this.properties.getDefaultEncoding().name());
+		sender.setSession(session);
+		return sender;
+	}
+
 	@Bean
 	@ConditionalOnMissingBean
 	public Session session() {

spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/mail/MailSenderPropertiesConfiguration.java

+/*
+ * Copyright 2012-2018 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.mail;
+
+import java.util.Map;
+import java.util.Properties;
+
+import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.mail.MailSender;
+import org.springframework.mail.javamail.JavaMailSenderImpl;
+
+/**
+ * Auto-configure a {@link MailSender} based on properties configuration.
+ *
+ * @author Oliver Gierke
+ * @author Eddú Meléndez
+ * @author Stephane Nicoll
+ */
+@Configuration
+@ConditionalOnProperty(prefix = "spring.mail", name = "host")
+class MailSenderPropertiesConfiguration {
+
+	private final MailProperties properties;
+
+	MailSenderPropertiesConfiguration(MailProperties properties) {
+		this.properties = properties;
+	}
+
+	@Bean
+	@ConditionalOnMissingBean
+	public JavaMailSenderImpl mailSender() {
+		JavaMailSenderImpl sender = new JavaMailSenderImpl();
+		applyProperties(sender);
+		return sender;
+	}
+
+	private void applyProperties(JavaMailSenderImpl sender) {
+		sender.setHost(this.properties.getHost());
+		if (this.properties.getPort() != null) {
+			sender.setPort(this.properties.getPort());
+		}
+		sender.setUsername(this.properties.getUsername());
+		sender.setPassword(this.properties.getPassword());
+		sender.setProtocol(this.properties.getProtocol());
+		if (this.properties.getDefaultEncoding() != null) {
+			sender.setDefaultEncoding(this.properties.getDefaultEncoding().name());
+		}
+		if (!this.properties.getProperties().isEmpty()) {
+			sender.setJavaMailProperties(asProperties(this.properties.getProperties()));
+		}
+	}
+
+	private Properties asProperties(Map<String, String> source) {
+		Properties properties = new Properties();
+		properties.putAll(source);
+		return properties;
+	}
+
+}

spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/mail/MailSenderAutoConfigurationTests.java

 /*
- * Copyright 2012-2016 the original author or authors.
+ * Copyright 2012-2018 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.
@@ -178,6 +178,36 @@ public class MailSenderAutoConfigurationTests {
 		load(EmptyConfig.class, "spring.mail.jndi-name:foo");
 	}
 
+	@Test
+	public void jndiSessionTakesPrecedenceOverProperties() throws NamingException {
+		Session session = configureJndiSession("foo");
+		load(EmptyConfig.class, "spring.mail.jndi-name:foo",
+				"spring.mail.host:localhost");
+		Session sessionBean = this.context.getBean(Session.class);
+		assertThat(sessionBean).isEqualTo(session);
+		assertThat(this.context.getBean(JavaMailSenderImpl.class).getSession())
+				.isEqualTo(sessionBean);
+	}
+
+	@Test
+	public void defaultEncodingWithProperties() {
+		load(EmptyConfig.class, "spring.mail.host:localhost",
+				"spring.mail.default-encoding:UTF-16");
+		JavaMailSenderImpl bean = (JavaMailSenderImpl) this.context
+				.getBean(JavaMailSender.class);
+		assertThat(bean.getDefaultEncoding()).isEqualTo("UTF-16");
+	}
+
+	@Test
+	public void defaultEncodingWithJndi() throws NamingException {
+		configureJndiSession("foo");
+		load(EmptyConfig.class, "spring.mail.jndi-name:foo",
+				"spring.mail.default-encoding:UTF-16");
+		JavaMailSenderImpl bean = (JavaMailSenderImpl) this.context
+				.getBean(JavaMailSender.class);
+		assertThat(bean.getDefaultEncoding()).isEqualTo("UTF-16");
+	}
+
 	@Test
 	public void connectionOnStartup() throws MessagingException {
 		load(MockMailConfiguration.class, "spring.mail.host:10.0.0.23",

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

@@ -96,10 +96,10 @@ content into your application; rather pick only the properties that you need.
 	# Email ({sc-spring-boot-autoconfigure}/mail/MailProperties.{sc-ext}[MailProperties])
 	spring.mail.default-encoding=UTF-8 # Default MimeMessage encoding.
 	spring.mail.host= # SMTP server host. For instance `smtp.example.com`
-	spring.mail.jndi-name= # Session JNDI name. When set, takes precedence to others mail settings.
+	spring.mail.jndi-name= # Session JNDI name. When set, takes precedence to others Session settings.
 	spring.mail.password= # Login password of the SMTP server.
 	spring.mail.port= # SMTP server port.
-	spring.mail.properties.*= # Additional JavaMail session properties.
+	spring.mail.properties.*= # Additional JavaMail Session properties.
 	spring.mail.protocol=smtp # Protocol used by the SMTP server.
 	spring.mail.test-connection=false # Test that the mail server is available on startup.
 	spring.mail.username= # Login user of the SMTP server.

spring-boot-docs/src/main/asciidoc/spring-boot-features.adoc

@@ -5046,6 +5046,15 @@ to avoid having a thread blocked by an unresponsive mail server:
 	spring.mail.properties.mail.smtp.writetimeout=5000
 ----
 
+It is also possible to configure a `JavaMailSender` with an existing `Session` from JNDI:
+
+[source,properties,indent=0]
+----
+	spring.mail.jndi-name=mail/Session
+----
+
+When a `jndi-name` is set, it takes precedence over all other Session-related settings.
+
 
 
 [[boot-features-jta]]