Add default methods to MailSender and JavaMailSender as appropriate

spring-context-support/src/main/java/org/springframework/mail/MailSender.java

@@ -38,7 +38,9 @@ public interface MailSender {
 	 * @throws MailAuthenticationException in case of authentication failure
 	 * @throws MailSendException in case of failure when sending the message
 	 */
-	void send(SimpleMailMessage simpleMessage) throws MailException;
+	default void send(SimpleMailMessage simpleMessage) throws MailException {
+		send(new SimpleMailMessage[] {simpleMessage});
+	}
 
 	/**
 	 * Send the given array of simple mail messages in batch.

spring-context-support/src/main/java/org/springframework/mail/javamail/JavaMailSender.java

@@ -17,11 +17,17 @@
 package org.springframework.mail.javamail;
 
 import java.io.InputStream;
+import java.util.ArrayList;
+import java.util.List;
 
+import javax.mail.MessagingException;
 import javax.mail.internet.MimeMessage;
 
 import org.springframework.mail.MailException;
+import org.springframework.mail.MailParseException;
+import org.springframework.mail.MailPreparationException;
 import org.springframework.mail.MailSender;
+import org.springframework.mail.SimpleMailMessage;
 
 /**
  * Extended {@link org.springframework.mail.MailSender} interface for JavaMail,
@@ -82,6 +88,26 @@ public interface JavaMailSender extends MailSender {
 	*/
 	MimeMessage createMimeMessage(InputStream contentStream) throws MailException;
 
+
+	//---------------------------------------------------------------------
+	// Implementation of MailSender
+	//---------------------------------------------------------------------
+
+	@Override
+	default void send(SimpleMailMessage... simpleMessages) throws MailException {
+		List<MimeMessage> mimeMessages = new ArrayList<>(simpleMessages.length);
+		for (SimpleMailMessage simpleMessage : simpleMessages) {
+			MimeMailMessage message = new MimeMailMessage(createMimeMessage());
+			simpleMessage.copyTo(message);
+			MimeMessage mimeMessage = message.getMimeMessage();
+			if (mimeMessage instanceof SmartMimeMessage) {
+				((SmartMimeMessage) mimeMessage).setOriginalSimpleMailMessage(simpleMessage);
+			}
+			mimeMessages.add(mimeMessage);
+		}
+		send(mimeMessages.toArray(new MimeMessage[0]));
+	}
+
 	/**
 	 * Send the given JavaMail MIME message.
 	 * The message needs to have been created with {@link #createMimeMessage()}.
@@ -92,7 +118,9 @@ public interface JavaMailSender extends MailSender {
 	 * in case of failure when sending the message
 	 * @see #createMimeMessage
 	 */
-	void send(MimeMessage mimeMessage) throws MailException;
+	default void send(MimeMessage mimeMessage) throws MailException {
+		send(new MimeMessage[] {mimeMessage});
+	}
 
 	/**
 	 * Send the given array of JavaMail MIME messages in batch.
@@ -121,7 +149,9 @@ public interface JavaMailSender extends MailSender {
 	 * @throws org.springframework.mail.MailSendException
 	 * in case of failure when sending the message
 	 */
-	void send(MimeMessagePreparator mimeMessagePreparator) throws MailException;
+	default void send(MimeMessagePreparator mimeMessagePreparator) throws MailException {
+		send(new MimeMessagePreparator[] {mimeMessagePreparator});
+	}
 
 	/**
 	 * Send the JavaMail MIME messages prepared by the given MimeMessagePreparators.
@@ -138,6 +168,25 @@ public interface JavaMailSender extends MailSender {
 	 * @throws org.springframework.mail.MailSendException
 	 * in case of failure when sending a message
 	 */
-	void send(MimeMessagePreparator... mimeMessagePreparators) throws MailException;
+	default void send(MimeMessagePreparator... mimeMessagePreparators) throws MailException {
+		try {
+			List<MimeMessage> mimeMessages = new ArrayList<>(mimeMessagePreparators.length);
+			for (MimeMessagePreparator preparator : mimeMessagePreparators) {
+				MimeMessage mimeMessage = createMimeMessage();
+				preparator.prepare(mimeMessage);
+				mimeMessages.add(mimeMessage);
+			}
+			send(mimeMessages.toArray(new MimeMessage[0]));
+		}
+		catch (MailException ex) {
+			throw ex;
+		}
+		catch (MessagingException ex) {
+			throw new MailParseException(ex);
+		}
+		catch (Exception ex) {
+			throw new MailPreparationException(ex);
+		}
+	}
 
 }

spring-context-support/src/main/java/org/springframework/mail/javamail/JavaMailSenderDecorator.java

@@ -0,0 +1,88 @@
+/*
+ * Copyright 2002-2019 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.mail.javamail;
+
+import java.io.InputStream;
+
+import javax.mail.internet.MimeMessage;
+
+import org.springframework.mail.MailException;
+import org.springframework.mail.SimpleMailMessage;
+
+
+/**
+ * A decorator pattern facility for a {@link JavaMailSender}, where the sending
+ * operation can be customized (e.g. implement a whitelist, feature-toggle, etc)
+ * by overriding {@link JavaMailSenderDecorator#send(MimeMessage...)}.
+ * Any deriving class <em>may</em> also override the methods to
+ * {@link #createMimeMessage() create messages}, if applicable, but this is not
+ * a requirement.
+ *
+ * <h2>Implementation note</h2>
+ * When overriding {@link #send(MimeMessage...)}, the decorated
+ * {@code JavaMailSender} can be accessed as {@code super.}{@link #decoratedMailSender}.
+ *
+ * @author Rune Flobakk
+ */
+public abstract class JavaMailSenderDecorator implements JavaMailSender {
+
+	/**
+	 * The decorated {@link JavaMailSender} which may (or not) be delegated to
+	 * by {@link #send(MimeMessage...)}.
+	 */
+	protected final JavaMailSender decoratedMailSender;
+
+	public JavaMailSenderDecorator(JavaMailSender decoratedMailSender) {
+		this.decoratedMailSender = decoratedMailSender;
+	}
+
+	@Override
+	public MimeMessage createMimeMessage() {
+		return this.decoratedMailSender.createMimeMessage();
+	}
+
+	@Override
+	public MimeMessage createMimeMessage(InputStream contentStream) throws MailException {
+		return this.decoratedMailSender.createMimeMessage(contentStream);
+	}
+
+	@Override
+	public final void send(SimpleMailMessage simpleMessage) throws MailException {
+		JavaMailSender.super.send(simpleMessage);
+	}
+
+	@Override
+	public final void send(SimpleMailMessage... simpleMessages) throws MailException {
+		JavaMailSender.super.send(simpleMessages);
+	}
+
+	@Override
+	public final void send(MimeMessage mimeMessage) throws MailException {
+		JavaMailSender.super.send(mimeMessage);
+	}
+
+	@Override
+	public final void send(MimeMessagePreparator mimeMessagePreparator) throws MailException {
+		JavaMailSender.super.send(mimeMessagePreparator);
+	}
+
+	@Override
+	public final void send(MimeMessagePreparator... mimeMessagePreparators) throws MailException {
+		JavaMailSender.super.send(mimeMessagePreparators);
+	}
+
+}

spring-context-support/src/main/java/org/springframework/mail/javamail/JavaMailSenderImpl.java

@@ -17,10 +17,8 @@
 package org.springframework.mail.javamail;
 
 import java.io.InputStream;
-import java.util.ArrayList;
 import java.util.Date;
 import java.util.LinkedHashMap;
-import java.util.List;
 import java.util.Map;
 import java.util.Properties;
 
@@ -37,7 +35,6 @@
 import org.springframework.mail.MailAuthenticationException;
 import org.springframework.mail.MailException;
 import org.springframework.mail.MailParseException;
-import org.springframework.mail.MailPreparationException;
 import org.springframework.mail.MailSendException;
 import org.springframework.mail.SimpleMailMessage;
 import org.springframework.util.Assert;
@@ -303,27 +300,6 @@ public FileTypeMap getDefaultFileTypeMap() {
 	}
 
 
-	//---------------------------------------------------------------------
-	// Implementation of MailSender
-	//---------------------------------------------------------------------
-
-	@Override
-	public void send(SimpleMailMessage simpleMessage) throws MailException {
-		send(new SimpleMailMessage[] {simpleMessage});
-	}
-
-	@Override
-	public void send(SimpleMailMessage... simpleMessages) throws MailException {
-		List<MimeMessage> mimeMessages = new ArrayList<>(simpleMessages.length);
-		for (SimpleMailMessage simpleMessage : simpleMessages) {
-			MimeMailMessage message = new MimeMailMessage(createMimeMessage());
-			simpleMessage.copyTo(message);
-			mimeMessages.add(message.getMimeMessage());
-		}
-		doSend(mimeMessages.toArray(new MimeMessage[0]), simpleMessages);
-	}
-
-
 	//---------------------------------------------------------------------
 	// Implementation of JavaMailSender
 	//---------------------------------------------------------------------
@@ -351,43 +327,11 @@ public MimeMessage createMimeMessage(InputStream contentStream) throws MailExcep
 		}
 	}
 
-	@Override
-	public void send(MimeMessage mimeMessage) throws MailException {
-		send(new MimeMessage[] {mimeMessage});
-	}
-
 	@Override
 	public void send(MimeMessage... mimeMessages) throws MailException {
 		doSend(mimeMessages, null);
 	}
 
-	@Override
-	public void send(MimeMessagePreparator mimeMessagePreparator) throws MailException {
-		send(new MimeMessagePreparator[] {mimeMessagePreparator});
-	}
-
-	@Override
-	public void send(MimeMessagePreparator... mimeMessagePreparators) throws MailException {
-		try {
-			List<MimeMessage> mimeMessages = new ArrayList<>(mimeMessagePreparators.length);
-			for (MimeMessagePreparator preparator : mimeMessagePreparators) {
-				MimeMessage mimeMessage = createMimeMessage();
-				preparator.prepare(mimeMessage);
-				mimeMessages.add(mimeMessage);
-			}
-			send(mimeMessages.toArray(new MimeMessage[0]));
-		}
-		catch (MailException ex) {
-			throw ex;
-		}
-		catch (MessagingException ex) {
-			throw new MailParseException(ex);
-		}
-		catch (Exception ex) {
-			throw new MailPreparationException(ex);
-		}
-	}
-
 	/**
 	 * Validate that this instance can connect to the server that it is configured
 	 * for. Throws a {@link MessagingException} if the connection attempt failed.
@@ -442,7 +386,7 @@ protected void doSend(MimeMessage[] mimeMessages, @Nullable Object[] originalMes
 					catch (Exception ex) {
 						// Effectively, all remaining messages failed...
 						for (int j = i; j < mimeMessages.length; j++) {
-							Object original = (originalMessages != null ? originalMessages[j] : mimeMessages[j]);
+							Object original = (originalMessages != null ? originalMessages[j] : resolveOriginal(mimeMessages[j]));
 							failedMessages.put(original, ex);
 						}
 						throw new MailSendException("Mail server connection failed", ex, failedMessages);
@@ -465,7 +409,7 @@ protected void doSend(MimeMessage[] mimeMessages, @Nullable Object[] originalMes
 					transport.sendMessage(mimeMessage, (addresses != null ? addresses : new Address[0]));
 				}
 				catch (Exception ex) {
-					Object original = (originalMessages != null ? originalMessages[i] : mimeMessage);
+					Object original = (originalMessages != null ? originalMessages[i] : resolveOriginal(mimeMessage));
 					failedMessages.put(original, ex);
 				}
 			}
@@ -492,6 +436,10 @@ protected void doSend(MimeMessage[] mimeMessages, @Nullable Object[] originalMes
 		}
 	}
 
+	private static Object resolveOriginal(MimeMessage mimeMessage) {
+		return mimeMessage instanceof SmartMimeMessage ? ((SmartMimeMessage) mimeMessage).getOriginalOrElseThis() : mimeMessage;
+	}
+
 	/**
 	 * Obtain and connect a Transport from the underlying JavaMail Session,
 	 * passing in the specified host, port, username, and password.

spring-context-support/src/main/java/org/springframework/mail/javamail/SmartMimeMessage.java

@@ -21,6 +21,7 @@
 import javax.mail.internet.MimeMessage;
 
 import org.springframework.lang.Nullable;
+import org.springframework.mail.SimpleMailMessage;
 
 /**
  * Special subclass of the standard JavaMail {@link MimeMessage}, carrying a
@@ -45,6 +46,9 @@ class SmartMimeMessage extends MimeMessage {
 	@Nullable
 	private final FileTypeMap defaultFileTypeMap;
 
+	@Nullable
+	private SimpleMailMessage originalMessage;
+
 
 	/**
 	 * Create a new SmartMimeMessage.
@@ -60,6 +64,13 @@ public SmartMimeMessage(
 		this.defaultFileTypeMap = defaultFileTypeMap;
 	}
 
+	void setOriginalSimpleMailMessage(@Nullable SimpleMailMessage originalMessage) {
+		this.originalMessage = originalMessage;
+	}
+
+	Object getOriginalOrElseThis() {
+		return this.originalMessage != null ? this.originalMessage : this;
+	}
 
 	/**
 	 * Return the default encoding of this message, or {@code null} if none.