How do I debug application that uses JavaMail APIs?

By Wayan in Mail 0 Comment

To ask Java mail to print out a debug message when you run a Java mail program you can add the mail.debug and set the value to true into the properties used to create the session object.

The other way is to set the debug setting of the session using the session.setDebug() method and pass true as the parameter. This will also turn on the debug message in your Java mail program.

package org.kodejava.mail;

import javax.mail.*;
import javax.mail.internet.InternetAddress;
import javax.mail.internet.MimeMessage;
import java.util.Date;
import java.util.Properties;

public class MailDebugDemo {
    public static void main(String[] args) {
        MailDebugDemo.sendMail("[email protected]", "[email protected]",
                "Debug Demo", "Mail Debug Demo");
    }

    private static void sendMail(String mailFrom, String mailTo, String mailSubject,
                                 String mailText) {
        Properties props = new Properties() {{
            put("mail.smtp.auth", "true");
            put("mail.smtp.host", "smtp.gmail.com");
            put("mail.transport.protocol", "smtp");
            put("mail.smtp.port", "587");
            put("mail.smtp.starttls.enable", "true");
            put("mail.smtp.ssl.protocols", "TLSv1.2");
            put("mail.debug", "true");
        }};

        // Creates a mail session. We need to supply username and
        // password for GMail authentication.
        Session session = Session.getInstance(props, new Authenticator() {
            @Override
            protected PasswordAuthentication getPasswordAuthentication() {
                return new PasswordAuthentication("[email protected]", "password");
            }
        });

        try {
            // Creates email message
            Message message = new MimeMessage(session);
            message.setSentDate(new Date());
            message.setFrom(new InternetAddress(mailFrom));
            message.setRecipient(Message.RecipientType.TO,
                    new InternetAddress(mailTo));
            message.setSubject(mailSubject);
            message.setText(mailText);

            // Send a message
            Transport.send(message);
        } catch (MessagingException e) {
            e.printStackTrace();
        }
    }
}

Here is an example of debug information produce by the JavaMail API when sending an email using Gmail SMTP server.

DEBUG: JavaMail version 1.5.6
DEBUG: successfully loaded resource: /META-INF/javamail.default.providers
DEBUG: Tables of loaded providers
DEBUG: Providers Listed By Class Name: {com.sun.mail.smtp.SMTPSSLTransport=javax.mail.Provider[TRANSPORT,smtps,com.sun.mail.smtp.SMTPSSLTransport,Oracle], com.sun.mail.smtp.SMTPTransport=javax.mail.Provider[TRANSPORT,smtp,com.sun.mail.smtp.SMTPTransport,Oracle], com.sun.mail.imap.IMAPSSLStore=javax.mail.Provider[STORE,imaps,com.sun.mail.imap.IMAPSSLStore,Oracle], com.sun.mail.pop3.POP3SSLStore=javax.mail.Provider[STORE,pop3s,com.sun.mail.pop3.POP3SSLStore,Oracle], com.sun.mail.imap.IMAPStore=javax.mail.Provider[STORE,imap,com.sun.mail.imap.IMAPStore,Oracle], com.sun.mail.pop3.POP3Store=javax.mail.Provider[STORE,pop3,com.sun.mail.pop3.POP3Store,Oracle]}
DEBUG: Providers Listed By Protocol: {imaps=javax.mail.Provider[STORE,imaps,com.sun.mail.imap.IMAPSSLStore,Oracle], imap=javax.mail.Provider[STORE,imap,com.sun.mail.imap.IMAPStore,Oracle], smtps=javax.mail.Provider[TRANSPORT,smtps,com.sun.mail.smtp.SMTPSSLTransport,Oracle], pop3=javax.mail.Provider[STORE,pop3,com.sun.mail.pop3.POP3Store,Oracle], pop3s=javax.mail.Provider[STORE,pop3s,com.sun.mail.pop3.POP3SSLStore,Oracle], smtp=javax.mail.Provider[TRANSPORT,smtp,com.sun.mail.smtp.SMTPTransport,Oracle]}
DEBUG: successfully loaded resource: /META-INF/javamail.default.address.map
DEBUG: getProvider() returning javax.mail.Provider[TRANSPORT,smtp,com.sun.mail.smtp.SMTPTransport,Oracle]
DEBUG SMTP: useEhlo true, useAuth true
DEBUG SMTP: useEhlo true, useAuth true
DEBUG SMTP: trying to connect to host "smtp.gmail.com", port 587, isSSL false
220 smtp.gmail.com ESMTP b2sm4488826pgh.33 - gsmtp
DEBUG SMTP: connected to host "smtp.gmail.com", port: 587
...
...

Maven Dependencies

<dependencies>
    <dependency>
        <groupId>javax.mail</groupId>
        <artifactId>javax.mail-api</artifactId>
        <version>1.5.6</version>
    </dependency>
    <dependency>
        <groupId>javax.mail</groupId>
        <artifactId>mail</artifactId>
        <version>1.4.7</version>
    </dependency>
</dependencies>

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How do I validate email address using Java Mail API?

By Wayan in Mail 0 Comment

This code snippet shows you how to validate an email address using the javax.mail.internet.InternetAddress class. The validate() method throws a javax.mail.internet.AddressException when the email address passed to the constructor is not a valid email address.

Here is the complete code snippet:

package org.kodejava.mail;

import javax.mail.internet.AddressException;
import javax.mail.internet.InternetAddress;

public class ValidateEmail {
    public static void main(String[] args) {
        ValidateEmail demo = new ValidateEmail();

        String email = "[email protected]";
        boolean isValid = demo.validateEmail(email);
        demo.printStatus(email, isValid);

        email = "kodejava.example";
        isValid = demo.validateEmail(email);
        demo.printStatus(email, isValid);
    }

    private boolean validateEmail(String email) {
        boolean isValid = false;
        try {
            // Create InternetAddress object and validated the supplied
            // address which is this case is an email address.
            InternetAddress internetAddress = new InternetAddress(email);
            internetAddress.validate();
            isValid = true;
        } catch (AddressException e) {
            e.printStackTrace();
        }
        return isValid;
    }

    private void printStatus(String email, boolean valid) {
        System.out.println(email + " is " + (valid ? "a" : "not a") +
                " valid email address");
    }
}

When running the program you will get the following message printed on the screen.

[email protected] is a valid email address
kodejava.example is not a valid email address
javax.mail.internet.AddressException: Missing final '@domain' in string ``kodejava.example''
    at javax.mail.internet.InternetAddress.checkAddress(InternetAddress.java:1279)
    at javax.mail.internet.InternetAddress.validate(InternetAddress.java:1154)
    at org.kodejava.mail.ValidateEmail.validateEmail(ValidateEmail.java:25)
    at org.kodejava.mail.ValidateEmail.main(ValidateEmail.java:15)

Maven Dependencies

<dependencies>
    <dependency>
        <groupId>javax.mail</groupId>
        <artifactId>javax.mail-api</artifactId>
        <version>1.5.6</version>
    </dependency>
    <dependency>
        <groupId>javax.mail</groupId>
        <artifactId>mail</artifactId>
        <version>1.4.7</version>
    </dependency>
</dependencies>

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How do I read file using FileInputStream?

By Wayan in Core API, IO 0 Comment

The following example use the java.io.FileInputStream class to read contents of a text file. We’ll read a file located in the temporary directory defined by operating system. This temporary directory can be accessed using the java.io.tmpdir system property.

package org.kodejava.io;

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;

public class FileInputStreamDemo {
    public static void main(String[] args) {
        // Get the temporary directory. We'll read the data.txt file
        // from this directory.
        String tempDir = System.getProperty("java.io.tmpdir");
        File file = new File(tempDir + "/data.txt");

        StringBuilder builder = new StringBuilder();
        FileInputStream fis = null;
        try {
            // Create a FileInputStream to read the file.
            fis = new FileInputStream(file);

            int data;
            // Read the entire file data. When -1 is returned it
            // means no more content to read.
            while ((data = fis.read()) != -1) {
                builder.append((char) data);
            }
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            if (fis != null) {
                try {
                    fis.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }

        // Print the content of the file
        System.out.println("File Contents = " + builder);
    }
}

The content read from the input stream will be appended into a StringBuilder object. At the end of the snippet the content of the will be converted into string using the toString() method.

Here are the content of our data.txt file.

File Contents = Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book. It has survived not only five centuries, but also the leap into electronic typesetting, remaining essentially unchanged. It was popularised in the 1960s with the release of Letraset sheets containing Lorem Ipsum passages, and more recently with desktop publishing software like Aldus PageMaker including versions of Lorem Ipsum.

How do I disable keyboard events in JTextArea?

By Wayan in Swing 0 Comment

The following example demonstrate how to disable some keys in JTextArea and JScrollPane using the InputMap. In the disableKeys() method below we disable the arrow keys including the UP, DOWN, LEFT and RIGHT.

Let’s see the code snippet below:

package org.kodejava.swing;

import javax.swing.*;
import java.awt.*;

public class TextAreaDisableKeyDemo extends JFrame {
    public TextAreaDisableKeyDemo() {
        initialize();
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(
                () -> new TextAreaDisableKeyDemo().setVisible(true));
    }

    private void initialize() {
        setSize(500, 200);
        setTitle("Disable Keys Demo");
        setLayout(new BorderLayout());
        setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);

        JTextArea textArea = new JTextArea("Hello World!");
        JScrollPane scrollPane = new JScrollPane(textArea);
        disableKeys(textArea.getInputMap());
        disableKeys(scrollPane.getInputMap(
                JComponent.WHEN_ANCESTOR_OF_FOCUSED_COMPONENT));

        getContentPane().add(scrollPane, BorderLayout.CENTER);
    }

    private void disableKeys(InputMap inputMap) {
        String[] keys = {"UP", "DOWN", "LEFT", "RIGHT"};
        for (String key : keys) {
            inputMap.put(KeyStroke.getKeyStroke(key), "none");
        }
    }
}

The output of the code snippet above is:

Disable Keyboard Events in JTextArea

How do I create a single line JTextArea?

By Wayan in Swing 0 Comment

The following example will show you how to create a single line JTextArea. A single line means that you cannot insert a new line in the text area. When pressing the enter key it will be replaced by a space.

This can be done by putting a property called filterNewlines and set its value to Boolean.TRUE into the document model of the JTextArea.

package org.kodejava.swing;

import javax.swing.*;
import java.awt.*;

public class SingleLineTextArea extends JFrame {
    private SingleLineTextArea() {
        initialize();
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(
                () -> new SingleLineTextArea().setVisible(true));
    }

    private void initialize() {
        setSize(500, 200);
        setTitle("Single Line Text Area");
        setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
        setLayout(new BorderLayout());

        final JTextArea textArea = new JTextArea();
        textArea.setLineWrap(true);

        // Filter a new line, pressing enter key will be replaced
        // with a space instead.
        textArea.getDocument().putProperty("filterNewlines",
                Boolean.TRUE);

        JScrollPane scrollPane = new JScrollPane(textArea);

        // Pressing the Save button print out the text area text
        // into the console.
        JButton button = new JButton("Save");
        button.addActionListener(e -> System.out.println(textArea.getText()));
        getContentPane().add(scrollPane, BorderLayout.CENTER);
        getContentPane().add(button, BorderLayout.SOUTH);
    }
}

The screenshot of the result of the code snippet above is:

Single Line JTextArea Demo