// <applet code='StreamsApplet' width='400' height='200'></applet>
import javax.swing.*;
import javax.swing.event.*;
import java.awt.*;
import java.awt.event.*;
import java.io.*;
import java.util.*;

/**
From:
http://java.sun.com/developer/TechTips/txtarchive/2006/Mar06_JohnZ.txt
@author John Zukowski
*/
public class StreamsApplet extends JApplet {

	private static final String CHARSET = "UTF-8";
	JButton add;
	JButton remove;
	JList list;
	JTextField key;
	JTextField value;

	public void init() {
		JLabel keyLabel = new JLabel("Key");
		keyLabel.setDisplayedMnemonic('K');
		key = new JTextField();
		keyLabel.setLabelFor(key);
		JLabel valueLabel = new JLabel("Value");
		valueLabel.setDisplayedMnemonic('V');
		value = new JTextField();
		valueLabel.setLabelFor(value);
		JPanel topPanel = new JPanel(new GridLayout(2,2));
		topPanel.add(keyLabel);
		topPanel.add(key);
		topPanel.add(valueLabel);
		topPanel.add(value);
		add(topPanel, BorderLayout.NORTH);

		list = new JList();
		list.setSelectionMode(
		ListSelectionModel.SINGLE_SELECTION);
		JScrollPane pane = new JScrollPane(list);
		add(pane, BorderLayout.CENTER);

		add = new JButton("Add/Update");
		add.setMnemonic('A');
		remove = new JButton("Remove");
		remove.setMnemonic('R');
		JPanel bottomPanel = new JPanel();
		bottomPanel.add(add);
		bottomPanel.add(remove);
		add(bottomPanel, BorderLayout.SOUTH);

		ActionListener addListener = new ActionListener() {
			public void actionPerformed(ActionEvent e) {
				String keyText = key.getText();
				String valueText = value.getText();
				try {
					ByteArrayInputStream bais =
					new ByteArrayInputStream(
					valueText.getBytes(CHARSET));
					getAppletContext().setStream(keyText, bais);
				} catch (IOException ioe) {
					JOptionPane.showMessageDialog(StreamsApplet.this,
						"Unable to save", "Error",
						JOptionPane.ERROR_MESSAGE);
				}
				updateList();
				key.setText("");
				value.setText("");
			}
		};

		add.addActionListener(addListener);

		ActionListener removeListener = new ActionListener() {
			public void actionPerformed(ActionEvent e) {
				String keyText = key.getText();
				try {
					getAppletContext().setStream(keyText, null);
				} catch (IOException ioe) {
					JOptionPane.showMessageDialog(StreamsApplet.this,
						"Unable to clear", "Error",
						JOptionPane.ERROR_MESSAGE);
				}
				updateList();
				key.setText("");
				value.setText("");
			}
		};

		remove.addActionListener(removeListener);

		ListSelectionListener selectListener = new ListSelectionListener() {
			public void valueChanged(ListSelectionEvent e) {
				String selection = (String)list.getSelectedValue();
				try {
					InputStream stream =
						getAppletContext().getStream(selection);
					InputStreamReader isr =
						new InputStreamReader(stream, CHARSET);
					BufferedReader reader = new BufferedReader(isr);
					String line = reader.readLine();
					key.setText(selection);
					value.setText(line);
				} catch (IOException ioe) {
					JOptionPane.showMessageDialog(StreamsApplet.this,
						"Unable to read", "Error",
						JOptionPane.ERROR_MESSAGE);
				}
			}
		};
		list.addListSelectionListener(selectListener);

		updateList();
	}

	private void updateList() {
		DefaultListModel model = new DefaultListModel();
		Iterator iter =
			getAppletContext().getStreamKeys();
		if (iter != null) {
			while (iter.hasNext()) {
				model.addElement(iter.next());
			}
		}
		list.setModel(model);
	}
}