Aug 28, 2012

Step by step guide - Developing a MVC application using J2EE and MySQL


In this tutorial, we will create a simple J2EE application that performs CRUD (Create Read Update Delete) operations for User Management using Jsp, Servlet and MySQL.


Prerequisites


For this tutorial, we will need the following tools: (The older or newer version should also works). Moreover, basic Java knowledge is assumed.


  1. Eclipse IDE for Java EE Developers
  2. Apache Tomcat v6 or later
  3. MySQL Community Server and MySQL Workbench (GUI Tool)
  4. MySQL Connector for Java
  5. jstl.jar and standard.jar
You can get the required jars from your Tomcat. Check in this directory : (your tomcat directory)—>apache-tomcat-7.0.26-windows-x86—>apache-tomcat-7.0.26—>webapps—>examples—>WEB-INF—>lib

I will tell you where you should put these jars later.

jQuery for javascript capability. In this case, we only use it for the datepicker component

Create the database


First, lets create the database and table for User using the following SQL scripts:

create database UserDB;
use UserDB;
grant all on UserDB.* to 'admin'@'localhost' identified by 'test';

CREATE TABLE UserDB.`users` (
  `userid` int(11) NOT NULL AUTO_INCREMENT,
  `firstname` varchar(45) DEFAULT NULL,
  `lastname` varchar(45) DEFAULT NULL,
  `dob` date DEFAULT NULL,
  `email` varchar(100) DEFAULT NULL,
  PRIMARY KEY (`userid`)
) ENGINE=InnoDB AUTO_INCREMENT=9 DEFAULT CHARSET=utf8


Setting up Eclipse and Tomcat


Go to eclipse. Before we create a new project for our application, we need to setup the server. Select File—>New—>Other. From the tree, Select Server.

Choose Apache—>Tomcat v7.0 Server and set the runtime environment.

Next, create a new project. Select File—>New—>Dynamic Web Project.

Enter “SimpleJspServletDB” as the project name. Select target runtime to Apache Tomcat v7.0 which we already setup before. Click Finish.

Copy the standard.jar, mysql-connector jar and jstl jar to WEB-INF—>lib folder.

Creating Package structure


Create four packages in the src folder.
  • org.avid.controller: contains the servlets
  • org.avid.dao: contains the logic for database operation
  • org.avid.model: contains the POJO (Plain Old Java Object). Each class in this package represents the database table. For this tutorial, however, we only have one table.
  • org.avid.util : contains the class for initiating database connection

Creating Model - POJOs


Next, create a new Java class. in org.avid.model folder. Name it “User.java” and insert these following codes. Each of the variables in this class represents the field in USERS table in our database.

package org.avid.model;

import java.util.Date;

public class User {

    private int userid;
    private String firstName;
    private String lastName;
    private Date dob;
    private String email;
    public int getUserid() {
        return userid;
    }
    public void setUserid(int userid) {
        this.userid = userid;
    }
    public String getFirstName() {
        return firstName;
    }
    public void setFirstName(String firstName) {
        this.firstName = firstName;
    }
    public String getLastName() {
        return lastName;
    }
    public void setLastName(String lastName) {
        this.lastName = lastName;
    }
    public Date getDob() {
        return dob;
    }
    public void setDob(Date dob) {
        this.dob = dob;
    }
    public String getEmail() {
        return email;
    }
    public void setEmail(String email) {
        this.email = email;
    }
    @Override
    public String toString() {
        return "User [userid=" + userid + ", firstName=" + firstName
                + ", lastName=" + lastName + ", dob=" + dob + ", email="
                + email + "]";
    }  
}

Creating DB Connection Utility


Create a new class in org.avid.util package and name it DbUtil.java. This class handles the database connection to our MySQL server. In this class, we read a .properties file which contains the information necessary for the connection.

package org.avid.util;

import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.util.Properties;

public class DbUtil {

    private static Connection connection = null;

    public static Connection getConnection() {
        if (connection != null)
            return connection;
        else {
            try {
                Properties prop = new Properties();
                InputStream inputStream = DbUtil.class.getClassLoader().getResourceAsStream("/db.properties");
                prop.load(inputStream);
                String driver = prop.getProperty("driver");
                String url = prop.getProperty("url");
                String user = prop.getProperty("user");
                String password = prop.getProperty("password");
                Class.forName(driver);
                connection = DriverManager.getConnection(url, user, password);
            } catch (ClassNotFoundException e) {
                e.printStackTrace();
            } catch (SQLException e) {
                e.printStackTrace();
            } catch (FileNotFoundException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            }
            return connection;
        }

    }
}

Create the properties file directly under the src folder. Create a new file, name it db.properties. Put the following information inside.

driver=com.mysql.jdbc.Driver
url=jdbc:mysql://localhost:3306/test
user=admin
password=test

Creating Data Access Object (DAO)


Next, create a new class in org.avid.dao package, name it UserDao.java. Dao stands for Data Access Object. It contains the logic for  database operation.

package org.avid.dao;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.List;
import org.avid.model.User;
import org.avid.util.DbUtil;

public class UserDao {

    private Connection connection;

    public UserDao() {
        connection = DbUtil.getConnection();
    }

    public void addUser(User user) {
        try {
            PreparedStatement preparedStatement = connection
                    .prepareStatement("insert into users(firstname,lastname,dob,email) values (?, ?, ?, ? )");
            // Parameters start with 1
            preparedStatement.setString(1, user.getFirstName());
            preparedStatement.setString(2, user.getLastName());
            preparedStatement.setDate(3, new java.sql.Date(user.getDob().getTime()));
            preparedStatement.setString(4, user.getEmail());
            preparedStatement.executeUpdate();

        } catch (SQLException e) {
            e.printStackTrace();
        }
    }

    public void deleteUser(int userId) {
        try {
            PreparedStatement preparedStatement = connection
                    .prepareStatement("delete from users where userid=?");
            // Parameters start with 1
            preparedStatement.setInt(1, userId);
            preparedStatement.executeUpdate();

        } catch (SQLException e) {
            e.printStackTrace();
        }
    }

    public void updateUser(User user) {
        try {
            PreparedStatement preparedStatement = connection
                    .prepareStatement("update users set firstname=?, lastname=?, dob=?, email=?" +
                            "where userid=?");
            // Parameters start with 1
            preparedStatement.setString(1, user.getFirstName());
            preparedStatement.setString(2, user.getLastName());
            preparedStatement.setDate(3, new java.sql.Date(user.getDob().getTime()));
            preparedStatement.setString(4, user.getEmail());
            preparedStatement.setInt(5, user.getUserid());
            preparedStatement.executeUpdate();

        } catch (SQLException e) {
            e.printStackTrace();
        }
    }


    public List<User> getAllUsers() {
        List<User> users = new ArrayList<User>();
        try {
            Statement statement = connection.createStatement();
            ResultSet rs = statement.executeQuery("select * from users");
            while (rs.next()) {
                User user = new User();
                user.setUserid(rs.getInt("userid"));
                user.setFirstName(rs.getString("firstname"));
                user.setLastName(rs.getString("lastname"));
                user.setDob(rs.getDate("dob"));
                user.setEmail(rs.getString("email"));
                users.add(user);
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }

        return users;
    }

    public User getUserById(int userId) {
        User user = new User();
        try {
            PreparedStatement preparedStatement = connection.
                    prepareStatement("select * from users where userid=?");
            preparedStatement.setInt(1, userId);
            ResultSet rs = preparedStatement.executeQuery();

            if (rs.next()) {
                user.setUserid(rs.getInt("userid"));
                user.setFirstName(rs.getString("firstname"));
                user.setLastName(rs.getString("lastname"));
                user.setDob(rs.getDate("dob"));
                user.setEmail(rs.getString("email"));
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }

        return user;
    }
}


Creating Contrrollers


Finally, create a new Servlet inside the org.avid.controller package and name it UserController.java

package org.avid.controller;

import java.io.IOException;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;

import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.avid.dao.UserDao;
import org.avid.model.User;

public class UserController extends HttpServlet {
    private static final long serialVersionUID = 1L;
    private static String INSERT_OR_EDIT = "/user.jsp";
    private static String LIST_USER = "/listUser.jsp";
    private UserDao dao;

    public UserController() {
        super();
        dao = new UserDao();
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        String forward="";
        String action = request.getParameter("action");

        if (action.equalsIgnoreCase("delete")){
            int userId = Integer.parseInt(request.getParameter("userId"));
            dao.deleteUser(userId);
            forward = LIST_USER;
            request.setAttribute("users", dao.getAllUsers());  
        } else if (action.equalsIgnoreCase("edit")){
            forward = INSERT_OR_EDIT;
            int userId = Integer.parseInt(request.getParameter("userId"));
            User user = dao.getUserById(userId);
            request.setAttribute("user", user);
        } else if (action.equalsIgnoreCase("listUser")){
            forward = LIST_USER;
            request.setAttribute("users", dao.getAllUsers());
        } else {
            forward = INSERT_OR_EDIT;
        }

        RequestDispatcher view = request.getRequestDispatcher(forward);
        view.forward(request, response);
    }

    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        User user = new User();
        user.setFirstName(request.getParameter("firstName"));
        user.setLastName(request.getParameter("lastName"));
        try {
            Date dob = new SimpleDateFormat("MM/dd/yyyy").parse(request.getParameter("dob"));
            user.setDob(dob);
        } catch (ParseException e) {
            e.printStackTrace();
        }
        user.setEmail(request.getParameter("email"));
        String userid = request.getParameter("userid");
        if(userid == null || userid.isEmpty())
        {
            dao.addUser(user);
        }
        else
        {
            user.setUserid(Integer.parseInt(userid));
            dao.updateUser(user);
        }
        RequestDispatcher view = request.getRequestDispatcher(LIST_USER);
        request.setAttribute("users", dao.getAllUsers());
        view.forward(request, response);
    }
}

Creating View


Now, it’s time for us to create the jsp, the view for our application. Under the WebContent folder, create a jsp file, name it index.jsp


<%@ page language="java" contentType="text/html; charset=EUC-KR" pageEncoding="EUC-KR"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=EUC-KR">
<title>Insert title here</title>
</head>
<body>
<jsp:forward page="/UserController?action=listUser" />
</body>
</html>

This jsp serves as the entry point for our application. In this case, it will redirect the request to our servlet to list all the users in the database.

Next, create the jsp to list all the users in the WebContent folder. Name it listUser.jsp

<%@ page language="java" contentType="text/html; charset=EUC-KR" pageEncoding="EUC-KR"%>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>
<%@ taglib uri="http://java.sun.com/jsp/jstl/fmt" prefix="fmt"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">

<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=EUC-KR">
<title>Show All Users</title>
</head>
<body>
    <table border=1>
        <thead>
            <tr>
                <th>User Id</th>
                <th>First Name</th>
                <th>Last Name</th>
                <th>DOB</th>
                <th>Email</th>
                <th colspan=2>Action</th>
            </tr>
        </thead>
        <tbody>
            <c:forEach items="${users}" var="user">
                <tr>
                    <td><c:out value="${user.userid}" /></td>
                    <td><c:out value="${user.firstName}" /></td>
                    <td><c:out value="${user.lastName}" /></td>
                    <td><fmt:formatDate pattern="yyyy-MMM-dd" value="${user.dob}" /></td>
                    <td><c:out value="${user.email}" /></td>
                    <td><a href="UserController?action=edit&userId=<c:out value="${user.userid}"/>">Update</a></td>
                    <td><a href="UserController?action=delete&userId=<c:out value="${user.userid}"/>">Delete</a></td>
                </tr>
            </c:forEach>
        </tbody>
    </table>
    <p><a href="UserController?action=insert">Add User</a></p>
</body>
</html>

In this jsp, we use JSTL to connect between the jsp and the servlet. We should refrain from using scriplet inside the jsp because it will make the jsp more difficult to maintain. Not to mention it will make the jsp looks ugly.

Next, create a new jsp in WebContent folder and name it user.jsp

<%@ page language="java" contentType="text/html; charset=EUC-KR" pageEncoding="EUC-KR"%>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>
<%@ taglib uri="http://java.sun.com/jsp/jstl/fmt" prefix="fmt"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=EUC-KR">
<link type="text/css"
    href="css/ui-lightness/jquery-ui-1.8.18.custom.css" rel="stylesheet" />
<script type="text/javascript" src="js/jquery-1.7.1.min.js"></script>
<script type="text/javascript" src="js/jquery-ui-1.8.18.custom.min.js"></script>
<title>Add new user</title>
</head>
<body>
    <script>
        $(function() {
            $('input[name=dob]').datepicker();
        });
    </script>

    <form method="POST" action='UserController' name="frmAddUser">
        User ID : <input type="text" readonly="readonly" name="userid"
            value="<c:out value="${user.userid}" />" /> <br />
        First Name : <input
            type="text" name="firstName"
            value="<c:out value="${user.firstName}" />" /> <br />
        Last Name : <input
            type="text" name="lastName"
            value="<c:out value="${user.lastName}" />" /> <br />
        DOB : <input
            type="text" name="dob"
            value="<fmt:formatDate pattern="MM/dd/yyyy" value="${user.dob}" />" /> <br />
        Email : <input type="text" name="email"
            value="<c:out value="${user.email}" />" /> <br /> <input
            type="submit" value="Submit" />
    </form>
</body>
</html>


Deployment Descriptor



Lastly, check the web.xml file located in WebContent—>WEB-INF folder in your project structure. Make sure it looks like this

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" id="WebApp_ID" version="2.5">
  <display-name>SimpleJspServletDB</display-name>
  <welcome-file-list>
    <welcome-file>index.jsp</welcome-file>
  </welcome-file-list>
  <servlet>
    <description></description>
    <display-name>UserController</display-name>
    <servlet-name>UserController</servlet-name>
    <servlet-class>org.avid.controller.UserController</servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>UserController</servlet-name>
    <url-pattern>/UserController</url-pattern>
  </servlet-mapping>
</web-app>

That is it. Right click the project name and run it using Run As–>Run on server option.

Aug 19, 2012

JavaMail API Part 4 - Using secured protocol

There are many security measures we can implement into the system. We will take a special case of gmail which uses STARTTLS. STARTTLS is an extension to plain text communication protocols, which offers a way to upgrade a plain text connection to an encrypted (TLS or SSL) connection instead of using a separate port for encrypted communication.



Here is the code for sending email using host which implements STARTTLS.

package com.test;

import java.util.Properties;

import javax.activation.DataHandler;

import javax.activation.DataSource;

import javax.activation.FileDataSource;

import javax.mail.Message;

import javax.mail.MessagingException;

import javax.mail.Multipart;

import javax.mail.Session;

import javax.mail.Transport;

import javax.mail.internet.AddressException;

import javax.mail.internet.InternetAddress;

import javax.mail.internet.MimeBodyPart;

import javax.mail.internet.MimeMessage;

import javax.mail.internet.MimeMultipart;


public class SendMail {

   public static void main(String[] args) {

      String host = "smtp.gmail.com";

      String from = "sender@gmail.com";

      String pass = "sender's password";

      Properties props = System.getProperties();

      props.put("mail.smtp.starttls.enable", "true"); // added this line

      props.put("mail.smtp.host", host);

      props.put("mail.smtp.user", from);

      props.put("mail.smtp.password", pass);

      props.put("mail.smtp.port", "587");

      props.put("mail.smtp.auth", "true");

      String[] to = {"recipient1@abc.com, recipient2@abc.com"};

      String fileAttachment = "F:\\emoticons\\yawn.gif";

      Session session = Session.getDefaultInstance(props, null);

      MimeMessage message = new MimeMessage(session);

      try {

         message.setFrom(new InternetAddress(from));

         InternetAddress[] toAddress = new InternetAddress[to.length];

         // To get the array of addresses

         for( int i=0; i < to.length; i++ ) { // changed from a while loop

            toAddress[i] = new InternetAddress(to[i]);

         }

         for( int i=0; i < toAddress.length; i++) { // changed from a while loop

            message.addRecipient(Message.RecipientType.TO, toAddress[i]);

         }

         message.setSubject("sending in a group");

         // create the message part 

         MimeBodyPart messageBodyPart = new MimeBodyPart();

         //fill message

         messageBodyPart.setText("Hi");

         Multipart multipart = new MimeMultipart();

         multipart.addBodyPart(messageBodyPart);

         // Part two is attachment

         messageBodyPart = new MimeBodyPart();

         DataSource source = new FileDataSource(fileAttachment);

         messageBodyPart.setDataHandler(new DataHandler(source));

         messageBodyPart.setFileName(fileAttachment);

         multipart.addBodyPart(messageBodyPart);

         // Put parts in message

         message.setContent(multipart);

         Transport transport = session.getTransport("smtp");

         transport.connect(host, from, pass);

         transport.sendMessage(message, message.getAllRecipients());

         transport.close();

      } catch (AddressException e) {

         e.printStackTrace();

      } catch (MessagingException e) {

         e.printStackTrace();

      }
   }
}

JavaMail API Part 3 - Send attachment in email


Here is an example to send an email with attachment from your machine.

We assume that mail server is running on localhost and is connected to internet to send email.



For prerequisites please refer to my previous article on JavaMail API.


// File Name SendFileEmail.java



import java.util.*;

import javax.mail.*;

import javax.mail.internet.*;

import javax.activation.*;



public class SendFileEmail

{

   public static void main(String [] args)

   {

    

      // Recipient's email ID needs to be mentioned.

      String to = "abcd@gmail.com";

      // Sender's email ID needs to be mentioned

      String from = "web@gmail.com";

      // Assuming you are sending email from localhost

      String host = "localhost";

      // Get system properties

      Properties properties = System.getProperties();

      // Setup mail server

      properties.setProperty("mail.smtp.host", host);

      // Get the default Session object.

      Session session = Session.getDefaultInstance(properties);

      try{
         // Create a default MimeMessage object.

         MimeMessage message = new MimeMessage(session);

         // Set From: header field of the header.

         message.setFrom(new InternetAddress(from));

         // Set To: header field of the header.

         message.addRecipient(Message.RecipientType.TO, new InternetAddress(to));

         // Set Subject: header field

         message.setSubject("This is the Subject Line!");

         // Create the message part

         BodyPart messageBodyPart = new MimeBodyPart();

         // Fill the message

         messageBodyPart.setText("This is message body");

        

         // Create a multipar message

         Multipart multipart = new MimeMultipart();

         // Set text message part

         multipart.addBodyPart(messageBodyPart);

         // Part two is attachment

         messageBodyPart = new MimeBodyPart();

         String filename = "file.txt";

         DataSource source = new FileDataSource(filename);

         messageBodyPart.setDataHandler(new DataHandler(source));

         messageBodyPart.setFileName(filename);

         multipart.addBodyPart(messageBodyPart);

         // Send the complete message parts

         message.setContent(multipart );

         // Send message

         Transport.send(message);

         System.out.println("Sent message successfully....");

      }catch (MessagingException mex) {

         mex.printStackTrace();

      }

   }

}



Compile and run this program to send an HTML email:

$ java SendFileEmail

Sent message successfully....



User Authentication


If it is required to provide user ID and Password to the email server for authentication purpose then you can set these properties as follows:

props.setProperty("mail.user", "myuser");

props.setProperty("mail.password", "mypwd");



Rest of the email sending mechanism would remain as explained above.

JavaMail API Part 2 - Sending rich text in email

We send simple text in email in previous post in the series. In this article, we will send rich text. For rich text, MIME type is "text/html". The actual mail content is written in HTML. While sending email, HTML contents will be set and content type is set to "text/html".

We assume that mail server is running on localhost and is connected to internet to send email.

For prerequisites please refer to my previous article on JavaMail API.


Using this example, you can send as big as HTML content you like.

// File Name SendHTMLEmail.java

import java.util.*;
import javax.mail.*;
import javax.mail.internet.*;
import javax.activation.*;

public class SendHTMLEmail
{
   public static void main(String [] args)
   {
     
      // Recipient's email ID needs to be mentioned.
      String to = "abcd@gmail.com";
      // Sender's email ID needs to be mentioned
      String from = "web@gmail.com";
      // Assuming you are sending email from localhost
      String host = "localhost";
      // Get system properties
      Properties properties = System.getProperties();
      // Setup mail server
      properties.setProperty("mail.smtp.host", host);
      // Get the default Session object.
      Session session = Session.getDefaultInstance(properties);
      try{
         // Create a default MimeMessage object.
         MimeMessage message = new MimeMessage(session);
         // Set From: header field of the header.
         message.setFrom(new InternetAddress(from));
         // Set To: header field of the header.
         message.addRecipient(Message.RecipientType.TO, new InternetAddress(to));
         // Set Subject: header field
         message.setSubject("This is the Subject Line!");
         // Send the actual HTML message, as big as you like
         message.setContent("<h1>This is actual message</h1>", "text/html" );
         // Send message
         Transport.send(message);
         System.out.println("Sent message successfully....");
      }catch (MessagingException mex) {
         mex.printStackTrace();
      }
   }
}
Compile and run this program to send an HTML email:

$ java SendHTMLEmail
Sent message successfully....

Aug 18, 2012

JavaMail API Part 1 - Sending simple text email

There are many applications where system has to send an email to the user.
  • Notification
  • Validation
  • Reporting
  • Alarming etc
Sending email though look simple but it has many things to be considered like 
  • Whether email is a rich text or simple text
  • Whether email has attachment
  • Email using authentication
  • Emailing using secured protocols and mechanisms
Let's first take a simple case of sending a simple text email. We can write a simple standalone java application to send email. 

Prerequisites


We will need  JavaMail API and Java Activation Framework (JAF). You can download latest version from Oracle website.

Download and unzip these files, in the newly created top level directories you will find a number of jar files for both the applications. You need to add mail.jar and activation.jar files in your CLASSPATH.

We will also need mail server to send an email. There are many open source mail server we can use or we can use inbuilt mail server from operating system. Let's assume that mail server is running on localhost.

Sending Text Email


Following is the code.

// File Name SendMail.java

import java.util.*;
import javax.mail.*;
import javax.mail.internet.*;
import javax.activation.*;

public class SendMail
{
   public static void main(String [] args)
   {    
      // Recipient's email ID needs to be mentioned.
      String to = "abcd@gmail.com";
      // Sender's email ID needs to be mentioned
      String from = "web@gmail.com";
      // Assuming you are sending email from localhost
      String host = "localhost";
      // Get system properties
      Properties properties = System.getProperties();
      // Setup mail server
      properties.setProperty("mail.smtp.host", host);
      // Get the default Session object.
      Session session = Session.getDefaultInstance(properties);
      try{
         // Create a default MimeMessage object.
         MimeMessage message = new MimeMessage(session);
         // Set From: header field of the header.
         message.setFrom(new InternetAddress(from));
         // Set To: header field of the header.
         message.addRecipient(Message.RecipientType.TO, new InternetAddress(to));
         // Set Subject: header field
         message.setSubject("This is the Subject Line!");
         // Now set the actual message
         message.setText("This is actual message");
         // Send message
         Transport.send(message);
         System.out.println("Sent message successfully....");
      }catch (MessagingException mex) {
         mex.printStackTrace();
      }
   }
}

Compile and run this program to send a simple email:

$ java SendMail
Sent message successfully....


Sending Email to multiple recipient


If you want to send an email to multiple recipients then following methods would be used to specify multiple email IDs:

void addRecipients(Message.RecipientType type, Address [] addresses) MessagingException

Here is the description of the parameters:

  • type: This would be set to TO, CC or BCC. Here CC represents Carbon Copy and BCC represents Black Carbon Copy. Example Message.RecipientType.TO
  • addresses: This is the array of email ID. You would need to use InternetAddress() method while specifying email IDs