[New] Implemented a SmtpMailer and Strolch MailHandler component

SmtpMailer is a singleton and requires properties.

Configure the MailHandler as follows:
<Component>
    <name>MailHandler</name>
    <api>li.strolch.handler.mail.MailHandler</api>
    <impl>li.strolch.handler.mail.SmtpMailHandler</impl>
    <Properties>
        <fromAddr>relayer@eitchnet.ch</fromAddr>
        <fromName>Consilium</fromName>
        <overrideRecipientAddr>eitch@eitchnet.ch</overrideRecipientAddr>
        <overrideRecipientName>Consilium Test</overrideRecipientName>
        <username>relayer@eitchnet.ch</username>
        <password>M5ztAE4a1NWWZBHaUd2ey9aoH</password>
        <auth>true</auth>
        <startTls>true</startTls>
        <host>smtp.gmail.com</host>
        <port>587</port>
    </Properties>
</Component>

li.strolch.service/src/main/java/li/strolch/handler/mail/MailHandler.java

@@ -0,0 +1,28 @@
+package li.strolch.handler.mail;
+
+import li.strolch.agent.api.ComponentContainer;
+import li.strolch.agent.api.StrolchComponent;
+
+/**
+ * {@link StrolchComponent} to send e-mails
+ * 
+ * @author Robert von Burg <eitch@eitchnet.ch>
+ */
+public abstract class MailHandler extends StrolchComponent {
+
+	public MailHandler(ComponentContainer container, String componentName) {
+		super(container, componentName);
+	}
+
+	/**
+	 * Sends an e-mail to given recipient
+	 * 
+	 * @param subject
+	 *            the subject of the e-mail
+	 * @param text
+	 *            the test of the e-mail
+	 * @param recipient
+	 *            the address to whom to send the e-mail
+	 */
+	public abstract void sendMail(String subject, String text, String recipient);
+}

li.strolch.service/src/main/java/li/strolch/handler/mail/SmtpMailHandler.java

@@ -0,0 +1,37 @@
+package li.strolch.handler.mail;
+
+import li.strolch.agent.api.ComponentContainer;
+import li.strolch.runtime.configuration.ComponentConfiguration;
+import li.strolch.utils.SmtpMailer;
+
+/**
+ * SMTP {@link MailHandler}. Uses {@link SmtpMailer}
+ * 
+ * @author Robert von Burg <eitch@eitchnet.ch>
+ * 
+ * @see SmtpMailer
+ */
+public class SmtpMailHandler extends MailHandler {
+
+	public SmtpMailHandler(ComponentContainer container, String componentName) {
+		super(container, componentName);
+	}
+
+	/**
+	 * See {@link SmtpMailer} for which configuration properties are required
+	 * 
+	 * @see SmtpMailer
+	 */
+	@Override
+	public void initialize(ComponentConfiguration configuration) throws Exception {
+
+		SmtpMailer.init(configuration.getAsProperties());
+
+		super.initialize(configuration);
+	}
+
+	@Override
+	public void sendMail(String subject, String text, String recipient) {
+		SmtpMailer.getInstance().sendMail(subject, text, recipient);
+	}
+}

li.strolch.utils/pom.xml

@@ -1,6 +1,5 @@
 <?xml version="1.0"?>
-<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
-	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
 	<modelVersion>4.0.0</modelVersion>
 
 	<parent>
@@ -21,6 +20,13 @@
 			<groupId>org.slf4j</groupId>
 			<artifactId>slf4j-api</artifactId>
 		</dependency>
+
+		<!-- https://mvnrepository.com/artifact/javax.mail/mail -->
+		<dependency>
+			<groupId>javax.mail</groupId>
+			<artifactId>mail</artifactId>
+		</dependency>
+
 	</dependencies>
 
 	<build>

li.strolch.utils/src/main/java/li/strolch/utils/SmtpMailer.java

@@ -0,0 +1,149 @@
+package li.strolch.utils;
+
+import java.io.UnsupportedEncodingException;
+import java.text.MessageFormat;
+import java.util.Properties;
+
+import javax.mail.Message;
+import javax.mail.MessagingException;
+import javax.mail.PasswordAuthentication;
+import javax.mail.Session;
+import javax.mail.Transport;
+import javax.mail.internet.InternetAddress;
+import javax.mail.internet.MimeMessage;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * A simple helper class to send e-mails. Uses javax.mail and is built as a singleton, so configuration has to be done
+ * only once.
+ * 
+ * The {@link Properties} required are as follows:
+ * <ul>
+ * <li><code>fromAddr</code> and <code>fromName</code> - defines the address from which the e-mail comes from</li>
+ * <li><code>overrideRecipientAddr</code> and <code>overrideRecipientName</code> - if defined, overrides any recipient -
+ * useful for testng purposes</li>
+ * <li>username - the username to authenticate at the SMTP Server</li>
+ * <li>password - the password to authenticate at the SMTP Server</li>
+ * <li>auth - boolean to define if auth is to be done</li>
+ * <li>startTls - boolean to define if StartTLS is to be sent to the SMTP Server</li>
+ * <li>host - the SMTP host name</li>
+ * <li>port - the SMTP port</li>
+ * </ul>
+ * 
+ * @author Robert von Burg <eitch@eitchnet.ch>
+ */
+public class SmtpMailer {
+
+	private static final Logger logger = LoggerFactory.getLogger(SmtpMailer.class);
+
+	private static SmtpMailer instance;
+
+	/**
+	 * <p>
+	 * Initializes the SMTP Mailer with the given properties.
+	 * </p>
+	 * 
+	 * @param properties
+	 *            the properties to be used to initialize the mailer
+	 */
+	public static void init(Properties properties) {
+		try {
+			instance = new SmtpMailer(properties);
+		} catch (UnsupportedEncodingException e) {
+			throw new RuntimeException("Failed to initialize Mailer due to " + e.getMessage(), e);
+		}
+	}
+
+	/**
+	 * Returns the instance
+	 * 
+	 * @return the instance
+	 */
+	public static SmtpMailer getInstance() {
+		if (instance == null)
+			throw new RuntimeException("Instance not yet configured! Call init first!");
+		return instance;
+	}
+
+	private final InternetAddress from;
+	private final InternetAddress overrideRecipient;
+	private final String username;
+	private final String password;
+	private final Properties props;
+
+	/**
+	 * private constructor, use the {@link #init(Properties)}-method
+	 * 
+	 * @param properties
+	 *            the properties to initialize the mailer
+	 * 
+	 * @throws UnsupportedEncodingException
+	 *             if something goes wrong parsing the from or override addresses
+	 */
+	private SmtpMailer(Properties properties) throws UnsupportedEncodingException {
+
+		String fromAddr = properties.getProperty("fromAddr", null);
+		String fromName = properties.getProperty("fromName", null);
+		this.from = new InternetAddress(fromAddr, fromName);
+
+		if (properties.containsKey("overrideRecipientAddr")) {
+			String addr = properties.getProperty("overrideRecipientAddr", null);
+			String name = properties.getProperty("overrideRecipientName", null);
+			this.overrideRecipient = new InternetAddress(addr, name);
+		} else {
+			this.overrideRecipient = null;
+		}
+
+		this.username = properties.getProperty("username", null);
+		this.password = properties.getProperty("password", null);
+
+		this.props = new Properties();
+		props.put("mail.smtp.auth", properties.getProperty("auth", null));
+		props.put("mail.smtp.starttls.enable", properties.getProperty("startTls", null));
+		props.put("mail.smtp.host", properties.getProperty("host", null));
+		props.put("mail.smtp.port", properties.getProperty("port", null));
+
+	}
+
+	/**
+	 * Sends an e-mail to given recipient (unless override address defined).
+	 * 
+	 * @param subject
+	 *            the subject of the e-mail
+	 * @param text
+	 *            the test of the e-mail
+	 * @param recipient
+	 *            the address to whom to send the e-mail
+	 */
+	public void sendMail(String subject, String text, String recipient) {
+
+		try {
+
+			Session session = Session.getInstance(this.props, new javax.mail.Authenticator() {
+				protected PasswordAuthentication getPasswordAuthentication() {
+					return new PasswordAuthentication(SmtpMailer.this.username, SmtpMailer.this.password);
+				}
+			});
+
+			Message message = new MimeMessage(session);
+			message.setFrom(this.from);
+			if (this.overrideRecipient != null)
+				message.setRecipient(Message.RecipientType.TO, this.overrideRecipient);
+			else
+				message.addRecipients(Message.RecipientType.TO, InternetAddress.parse(recipient));
+
+			message.setSubject(subject);
+			message.setText(text);
+
+			Transport.send(message);
+
+			logger.info(MessageFormat.format("Sent E-mail to {0}: {1}",
+					message.getRecipients(Message.RecipientType.TO)[0], message.getSubject()));
+
+		} catch (MessagingException e) {
+			throw new RuntimeException("Failed to send e-mail due to " + e.getMessage(), e);
+		}
+	}
+}