Console.java

package org.egonet.util;

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

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class Console extends JFrame {
	
	final private static Logger logger = LoggerFactory.getLogger(Console.class);
	
    PipedInputStream piOut;
    PipedInputStream piErr;
    PipedOutputStream poOut;
    PipedOutputStream poErr;
    JTextArea textArea = new JTextArea();

    public Console() throws IOException {
        // Set up System.out
        piOut = new PipedInputStream();
        poOut = new PipedOutputStream(piOut);
        System.setOut(new PrintStream(poOut, true));

        // Set up System.err
        piErr = new PipedInputStream();
        poErr = new PipedOutputStream(piErr);
        System.setErr(new PrintStream(poErr, true));

        // Add a scrolling text area
        textArea.setEditable(false);
        textArea.setRows(20);
        textArea.setColumns(50);
        getContentPane().add(new JScrollPane(textArea), BorderLayout.CENTER);
        setTitle("Java Console");
        pack();
        setVisible(true);

        // Create reader threads
        new ReaderThread(piOut).start();
        new ReaderThread(piErr).start();
    }

    class ReaderThread extends Thread {
        PipedInputStream pi;

        ReaderThread(PipedInputStream pi) {
            this.pi = pi;
        }

        public void run() {
            final byte[] buf = new byte[1024];
            try {
                while (true) {
                    final int len = pi.read(buf);
                    if (len == -1) {
                        break;
                    }
                    final String strbuf = new String(buf, 0, len);
                    SwingUtilities.invokeLater(new Runnable() {
                        public void run() {
                            textArea.append(strbuf);

                            // Make sure the last line is always visible
                            textArea.setCaretPosition(textArea.getDocument().getLength());

                            // Keep the text area down to a certain character size
                            int idealSize = 1000;
                            int maxExcess = 500;
                            int excess = textArea.getDocument().getLength() - idealSize;
                            if (excess >= maxExcess) {
                                textArea.replaceRange("", 0, excess);
                                logger.info("BROKEN BROKEN BROKEN");
                            }
                        }
                    });
                }
            } catch (IOException e) {
            }
        }
    }
}