How to redirect javax.mail.Session setDebug to jTextArea

Question

How can I redirect javax.mail.Session setDebug to jTextArea ?

ByteArrayOutputStream os = new ByteArrayOutputStream();
PrintStream ps = new PrintStream(os);
Session mailSession = Session.getDefaultInstance(props, null);
logger.info("JAVAMAIL debug mode is ON");
mailSession.setDebug(true);
mailSession.setDebugOut(ps);
logger.info(os);

Answer 1

You could use the nice CustomOutputStream class described on http://www.codejava.net/java-se/swing/redirect-standard-output-streams-to-jtextarea:

import java.io.*;
import java.util.Properties;
import javax.mail.Session;
import javax.swing.*;

public class PrintStream2TextArea {
    public static void main(final String[] arguments) {
        new PrintStream2TextArea().launchGui();
    }

    private void launchGui() {
        final JFrame frame = new JFrame("Stack Overflow");
        frame.setBounds(100, 100, 800, 600);
        frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
        final JTextArea textArea = new JTextArea(42, 28);
        setupMailSession(new Properties(), textArea);
        frame.getContentPane().add(textArea);
        frame.setVisible(true);
    }

    private void setupMailSession(final Properties props, final JTextArea textArea) {
        PrintStream ps = new PrintStream(new CustomOutputStream(textArea));
        Session mailSession = Session.getDefaultInstance(props, null);
        //logger.info("JAVAMAIL debug mode is ON");
        mailSession.setDebug(true);
        mailSession.setDebugOut(ps);
        //logger.info(os);
    }

    /**
     * This class extends from OutputStream to redirect output to a JTextArea.
     *
     * @author www.codejava.net
     */
    public static class CustomOutputStream extends OutputStream {
        private JTextArea textArea;

        public CustomOutputStream(JTextArea textArea) {
            this.textArea = textArea;
        }

        @Override
        public void write(int b) throws IOException {
            // redirects data to the text area
            textArea.append(String.valueOf((char)b));
            // scrolls the text area to the end of data
            textArea.setCaretPosition(textArea.getDocument().getLength());
        }
    }
}

Answer 2

1. You can create or find a swing hander implementation and attach it to the javax.mail logger namespace used by JavaMail.
2. You can use threads and piped I/O to read the debug output and write it to the textarea.

3. You can create an buffered output stream that writes to the textarea during an 'autoflush'.

   public class AreaDebug {
   
       public static void main(String[] args) throws Exception {
           EventQueue.invokeAndWait(new Runnable() {
               @Override
               public void run() {
                   test();
               }
           });
       }
   
       private static void test() {
           assert EventQueue.isDispatchThread() : Thread.currentThread();
           final Session s = Session.getInstance(new Properties());
           JTextArea area = new JTextArea();
           Adaptor out = new Adaptor(area.getDocument());
           s.setDebugOut(new PrintStream(out, true)); //Default encoding?
           s.setDebug(true);
           System.out.println(area.getText());
       }
   
       private static class Adaptor extends ByteArrayOutputStream {
   
           private final Document d;
   
           Adaptor(final Document d) {
               this.d = d;
           }
   
           @Override
           public void flush() throws IOException {
               final String a;
               synchronized (this) {
                   super.flush();
                   a = super.toString(); //Default encoding?
                   super.reset();
               }
   
               Updater u = new Updater(d, a);
               if (EventQueue.isDispatchThread()) {
                   u.run();
               } else {
                   try {
                       EventQueue.invokeAndWait(u);
                   } catch (InterruptedException ex) {
                       Thread.currentThread().interrupt();
                       throw new InterruptedIOException();
                   } catch (InvocationTargetException ex) {
                       throw new IOException(ex);
                   }
               }
           }
       }
   
       private static class Updater implements Runnable {
   
           private final Document d;
           private final String append;
   
           Updater(Document d, String append) {
               this.d = d;
               this.append = append;
           }
   
           @Override
           public void run() {
               try {
                   d.insertString(d.getLength(), append, (AttributeSet) null);
               } catch (BadLocationException ex) {
                   Toolkit.getDefaultToolkit().beep();
               }
           }
       }
   }