In this article I'm going to show you how to send an email in the background without the user even knowing - the application will do everything behind the scenes.
Before we begin, you'll need to download a few files via the link below - this is a special version of the JavaMail API, which was written specifically for Android.
I'll be walking you through a Mail wrapper that I wrote, which makes it much easier to send emails and even add attachments if that's something you'd like to do.
Here is the full wrapper class below, which I'll go through step by step - keeping in mind that you'll have to add the fore-said files if you want this to work. Add them as external libraries - they need to be accessible by the Mail class.
import java.util.Date;
import java.util.Properties;
import javax.activation.CommandMap;
import javax.activation.DataHandler;
import javax.activation.DataSource;
import javax.activation.FileDataSource;
import javax.activation.MailcapCommandMap;
import javax.mail.BodyPart;
import javax.mail.Multipart;
import javax.mail.PasswordAuthentication;
import javax.mail.Session;
import javax.mail.Transport;
import javax.mail.internet.InternetAddress;
import javax.mail.internet.MimeBodyPart;
import javax.mail.internet.MimeMessage;
import javax.mail.internet.MimeMultipart;
public class Mail extends javax.mail.Authenticator {
private String _username;
private String _password;
private String[] _to;
private String _from;
private String _port;
private String _sport;
private String _host;
private String _subject;
private String _body;
private boolean _auth;
private boolean _debuggable;
private Multipart _multipart;
public Mail() {
_host = "smtp.gmail.com"; // default smtp server
_port = "465"; // default smtp port
_sport = "465"; // default socketfactory port
_username = ""; // username
_password = ""; // password
_from = ""; // email sent from
_subject = ""; // email subject
_body = ""; // email body
_debuggable = false; // debug mode on or off - default off
_auth = true; // smtp authentication - default on
_multipart = new MimeMultipart();
// There is something wrong with MailCap, javamail can not find a
// handler for the multipart/mixed part, so this bit needs to be added.
MailcapCommandMap mc = (MailcapCommandMap) CommandMap
.getDefaultCommandMap();
mc.addMailcap("text/html;; x-java-content-handler=com.sun.mail.handlers.text_html");
mc.addMailcap("text/xml;; x-java-content-handler=com.sun.mail.handlers.text_xml");
mc.addMailcap("text/plain;; x-java-content-handler=com.sun.mail.handlers.text_plain");
mc.addMailcap("multipart/*;; x-java-content-handler=com.sun.mail.handlers.multipart_mixed");
mc.addMailcap("message/rfc822;; x-java-content-handler=com.sun.mail.handlers.message_rfc822");
CommandMap.setDefaultCommandMap(mc);
}
public Mail(String user, String pass) {
this();
_username = user;
_password = pass;
}
public boolean send() throws Exception {
Properties props = _setProperties();
if (!_username.equals("") && !_password.equals("") && _to.length > 0
&& !_from.equals("") && !_subject.equals("")
&& !_body.equals("")) {
Session session = Session.getInstance(props, this);
MimeMessage msg = new MimeMessage(session);
msg.setFrom(new InternetAddress(_from));
InternetAddress[] addressTo = new InternetAddress[_to.length];
for (int i = 0; i < _to.length; i++) {
addressTo[i] = new InternetAddress(_to[i]);
}
msg.setRecipients(MimeMessage.RecipientType.TO, addressTo);
msg.setSubject(_subject);
msg.setSentDate(new Date());
// setup message body
BodyPart messageBodyPart = new MimeBodyPart();
messageBodyPart.setText(_body);
_multipart.addBodyPart(messageBodyPart);
// Put parts in message
msg.setContent(_multipart);
// send email
Transport.send(msg);
return true;
} else {
return false;
}
}
public void addAttachment(String filename) throws Exception {
BodyPart messageBodyPart = new MimeBodyPart();
DataSource source = new FileDataSource(filename);
messageBodyPart.setDataHandler(new DataHandler(source));
messageBodyPart.setFileName(filename);
_multipart.addBodyPart(messageBodyPart);
}
@Override
public PasswordAuthentication getPasswordAuthentication() {
return new PasswordAuthentication(_username, _password);
}
private Properties _setProperties() {
Properties props = new Properties();
props.put("mail.smtp.host", _host);
if (_debuggable) {
props.put("mail.debug", "true");
}
if (_auth) {
props.put("mail.smtp.auth", "true");
}
props.put("mail.smtp.port", _port);
props.put("mail.smtp.socketFactory.port", _sport);
props.put("mail.smtp.socketFactory.class",
"javax.net.ssl.SSLSocketFactory");
props.put("mail.smtp.socketFactory.fallback", "false");
return props;
}
// the getters and setters
public String getBody() {
return _body;
}
public void setBody(String _body) {
this._body = _body;
}
public void sendTo(String[] _to) {
this._to = _to;
}
public void sendFrom(String _from) {
this._from = _from;
}
public void setSubject(String _subject) {
this._subject = _subject;
}
// more of the getters and setters …..
}
And now I'm going to go through each bit of code
public Mail() {
_host = "smtp.gmail.com"; // default smtp server
_port = "465"; // default smtp port
_sport = "465"; // default socketfactory port
_username = ""; // username
_password = ""; // password
_from = ""; // email sent from
_subject = ""; // email subject
_body = ""; // email body
_debuggable = false; // debug mode on or off - default off
_auth = true; // smtp authentication - default on
_multipart = new MimeMultipart();
// There is something wrong with MailCap, javamail can not find a
// handler for the multipart/mixed part, so this bit needs to be added.
MailcapCommandMap mc = (MailcapCommandMap) CommandMap
.getDefaultCommandMap();
mc.addMailcap("text/html;; x-java-content-handler=com.sun.mail.handlers.text_html");
mc.addMailcap("text/xml;; x-java-content-handler=com.sun.mail.handlers.text_xml");
mc.addMailcap("text/plain;; x-java-content-handler=com.sun.mail.handlers.text_plain");
mc.addMailcap("multipart/*;; x-java-content-handler=com.sun.mail.handlers.multipart_mixed");
mc.addMailcap("message/rfc822;; x-java-content-handler=com.sun.mail.handlers.message_rfc822");
CommandMap.setDefaultCommandMap(mc);
}
public Mail(String user, String pass) {
this();
_username = user;
_password = pass;
}
In this piece of code we initialise the properties, and setup the default values.
Also, we're setting up the mime types for javamail. I've also added a comment which describes why we need this.
And you've probably noticed that there are 2 constructors - one overrides the other, just incase the you want to pass the username and password when instantiating the class.
public boolean send() throws Exception {
Properties props = _setProperties();
if (!_username.equals("") && !_password.equals("") && _to.length > 0
&& !_from.equals("") && !_subject.equals("")
&& !_body.equals("")) {
Session session = Session.getInstance(props, this);
MimeMessage msg = new MimeMessage(session);
msg.setFrom(new InternetAddress(_from));
InternetAddress[] addressTo = new InternetAddress[_to.length];
for (int i = 0; i < _to.length; i++) {
addressTo[i] = new InternetAddress(_to[i]);
}
msg.setRecipients(MimeMessage.RecipientType.TO, addressTo);
msg.setSubject(_subject);
msg.setSentDate(new Date());
// setup message body
BodyPart messageBodyPart = new MimeBodyPart();
messageBodyPart.setText(_body);
_multipart.addBodyPart(messageBodyPart);
// Put parts in message
msg.setContent(_multipart);
// send email
Transport.send(msg);
return true;
} else {
return false;
}
}
This is the most important method - here we're putting all the data from the properties and sending the mail.
public void addAttachment(String filename) throws Exception {
BodyPart messageBodyPart = new MimeBodyPart();
DataSource source = new FileDataSource(filename);
messageBodyPart.setDataHandler(new DataHandler(source));
messageBodyPart.setFileName(filename);
_multipart.addBodyPart(messageBodyPart);
}
You can call this method at any time if you want to add an attachment, but make sure you call it before the send method.
private Properties _setProperties() {
Properties props = new Properties();
props.put("mail.smtp.host", _host);
if (_debuggable) {
props.put("mail.debug", "true");
}
if (_auth) {
props.put("mail.smtp.auth", "true");
}
props.put("mail.smtp.port", _port);
props.put("mail.smtp.socketFactory.port", _sport);
props.put("mail.smtp.socketFactory.class",
"javax.net.ssl.SSLSocketFactory");
props.put("mail.smtp.socketFactory.fallback", "false");
return props;
}
Here we're setting up the properties for the mail retrieval - defaulting to SMTP authentication. Also keep in mind that this is all defaulted to connect to the Gmail (Google) SMTP server. Below is an example of how to use the Mail wrapper, in an Android activity.
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
if (mEmail.getText().toString().equals(
appPrefs.getEmail())) {
Mail m = new Mail("email@gmail.com", "password");
String[] toArr = {mEmail.getText().toString()};
m.sendTo(toArr);
m.sendFrom("email@gmail.com");
m.setSubject("Password");
m.setBody("This is your password : " + appPrefs.getPassword());
try {
m.addAttachment("/sdcard/filelocation");
if(m.send()) {
Toast.makeText(password.this, "Email was sent successfully.", Toast.LENGTH_LONG).show();
} else {
Toast.makeText(password.this, "Email was not sent.", Toast.LENGTH_LONG).show();
}
} catch(Exception e) {
//Toast.makeText(MailApp.this, "There was a problem sending the email.", Toast.LENGTH_LONG).show();
Log.e("Password", "Could not send email", e);
}
} else {
Toast
.makeText(
getBaseContext(),
"This is not that email which you enter when create account",
Toast.LENGTH_LONG).show();
}
}
});
