在Java中创建独立的GUI控制台，以扩展基于提示的应用程序

Question

I have several little applications which uses the standard console for retrieving user input and for showing messages troughtout System.in and System.out.

Now i would like to realize some Swing based class which called from these applications, it shows a frame with 2 text area, one for input (so associated to System.in) and another one (not editable) that shows the messages (hence associated to System.out). Actually i have implemented all, (actually creating a simple swing based gui and launching it from the event dispatcher thread is not so complex, the same for exporting all as a jar and including it as a library in the original project). The only problem I have so far, which took me here is about the swapping of the standard System.in and System.out to some custom ones which are associated with the 2 JTextArea . Actually checking some solutions online, I ended up with this few lines of code:

I use 2 PipedInputStream and a PrintWriter:

    private final PipedInputStream inPipe = new PipedInputStream(); 
    private final PipedInputStream outPipe = new PipedInputStream(); 
    private PrintWriter inWriter;

then i swap the streams

    System.setIn(inPipe); 
    System.setOut(new PrintStream(new PipedOutputStream(outPipe), true)); 
    inWriter = new PrintWriter(new PipedOutputStream(inPipe), true); 

for retrieving the data from the outPipe, I use a SwingWorker whose doInBackgroud method troughtout a Scanner reads the lines from the outPipe and publish them in order to append these string of lines in a not editable JTextArea. Meanwhile a keyListener checks for VK_ENTER click in order to get the text from the JTextField used as prompt, once this happens, the text is displayed using the System.out itself, and it effectively appears in the previous JTextArea, hence the SwingWorker described above works, and then I wrote the same line of text in the inWriter (the PrintStream object associated to the pipe related to the System.in) so the line should be available to be read from Reader objects which are present in the original application.

Unfortunately this is the only part of the code which does not work. Indeed, once i launch the new gui console, then change the streams, the original application will show only the text it prints on System.out, but when it wants to read the text the user writes, for instance troughtout either a BufferedReader or a Scanner object, nothing happens, as if the the in stream was empty.

I think this is due to the Scanner in the SwingWorker doInBackground method since when it reads the next line on the outPipe, it cleans the stream itself too. Any idea to get rid of this problem? I know i could write new methods for handling input and output but i would like to keep this not-intrusive approach, so without editing the original code, a part the creation of the gui Console object in the original application main method. Thanks in advance.

Update 1

This is the Console class, all is done here

public class Console extends JFrame implements KeyListener 
{

private JTextField prompt;
private JTextArea log;


private final PipedInputStream inPipe = new PipedInputStream(); 
private final PipedInputStream outPipe = new PipedInputStream(); 

private PrintWriter inWriter;


public Console(String title)
{
    super(title);

    System.setIn(inPipe); 

    try 
    {
        System.setOut(new PrintStream(new PipedOutputStream(outPipe), true)); 
        inWriter = new PrintWriter(new PipedOutputStream(inPipe), true); 
    }
    catch(IOException e) 
    {
        System.out.println("Error: " + e);
        return;
    }

    JPanel p = new JPanel();
    p.setLayout(null);
    log = new JTextArea();
    log.setEditable(false);
    log.setBounds(10, 10, 345, 250);
    p.add(log);
    prompt = new JTextField();
    prompt.setBounds(10, 270, 356, 80);
    prompt.addKeyListener(this);
    p.add(prompt);

    getContentPane().add(p);

    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    setVisible(true);
    setSize(392, 400);
    setLocationRelativeTo(null);

    (new SwingWorker<Void, String>() 
    { 
        protected Void doInBackground() throws Exception 
        { 
            Scanner s = new Scanner(outPipe);
            while (s.hasNextLine()) 
            {
                String line = s.nextLine();
                publish(line);
            }
            return null; 
        } 
        @Override 
        protected void process(java.util.List<String> chunks)
        { 
            for (String line : chunks) 
            {
                if (line.length() < 1)
                    continue;
                log.append(line.trim() + "\n"); 
            }
        } 
    }).execute(); 


}
    public void execute() 
{
    String text = prompt.getText();
    prompt.setText("");
    System.out.println(text); 
    inWriter.print(text.trim().replaceAll("\r\n", ""));
}


@Override
public void keyPressed(KeyEvent e)
{
    if (e.getKeyCode() == KeyEvent.VK_ENTER)
        execute();
}

@Override
public void keyReleased(KeyEvent e)
{
    if (e.getKeyCode() == KeyEvent.VK_ENTER)
        execute();

}

@Override
public void keyTyped(KeyEvent e)
{
    if (e.getKeyCode() == KeyEvent.VK_ENTER)
        execute();

}

// this is the method called from the original application
public static void setConsole(final String title) 
{
    EventQueue.invokeLater(new Runnable()
    {
        public void run()
        {
            new Console(title);
            //System.out.println("somewhat");
        }
    });

}

}

Answer 1

I found out the solution by myself, actually all the code posted in the 1st post is almost correct, the problem is with the reading from the System.in the original program, since it was done with a Scanner object (but i tested it with a BufferedReader too) and it seems it's something related to the string termination because if i read by using a simple System.in.read() call, i got the right data, of course char by char. Since both Scanner methods and read one are I/O blocking, I think it's something related to the termination of the string. Because when i wrote it on the InputStream, i cleared the string from any LF and CF char, as you can see in the above code, so when println is invoked only a \\r\\n should be appended. But reading the result char by char I see \\r\\n\\r\\n at the end, so i guess it should be something related to the ending of the string, even if i couldnt figured out the right way to handle it. I will keep you informated by updates tought, but however if you have suggestions and/or feedbacks, they will be obviously welcome.