Trying to run applet in JEditor

[Anthony Schmitt]

I'm attempting to place an open source applet that displays an SSH terminal (very nice piece of software called JTA) into my application. However, when I run my program I simply get an empty gray box where the internal editor frame is.

Here is my JInternalFrame:

TFrame = new javax.swing.JInternalFrame();
// Create an instance of the applet class.
      JApplet applet = new de.mud.jta.Applet();

      // Transfer the applet's context pane to the JFrame.
      TFrame.setContentPane(applet.getContentPane());

      // Transfer the applet's menu bar into the JFrame.
      // This line can be omitted if the applet
      // does not create a menu bar.
      TFrame.setJMenuBar(applet.getJMenuBar());

TFrame.setVisible(true);

Here is my Applet.class. I noticed it seems to have it's own init(), start(), stop(), etc., so I'm thinking if I can just call it correctly I don't need to init() or start() in my JInternalFrame, which is why I left them out.

package de.mud.jta;

import java.awt.datatransfer.Clipboard;
import java.util.Properties;
import javax.swing.JApplet;
import javax.swing.RootPaneContainer;

public class Applet extends JApplet {

    private static final int debug = 0;
    private String frameTitle;
    private RootPaneContainer appletFrame;
    private Properties options;
    private Common pluginLoader;
    private String host;
    private String port;
    private boolean disconnect;
    private boolean connect;
    private boolean disconnectCloseWindow;
    private Plugin focussedPlugin;
    private Clipboard clipboard;
    private boolean online;

    public Applet() {
        //compiled code
        throw new RuntimeException("Compiled Code");
    }

    public void init() {
        //compiled code
        throw new RuntimeException("Compiled Code");
    }

    public void start() {
        //compiled code
        throw new RuntimeException("Compiled Code");
    }

    public void stop() {
        //compiled code
        throw new RuntimeException("Compiled Code");
    }

    private void parameterOverride(Properties options) {
        //compiled code
        throw new RuntimeException("Compiled Code");
    }
}

Anyone have an idea about why my InternalJFrame isn't showing my applet?

[Tim Moores]

I'm confused. Is de.mud.jta.Applet your class, or the one you found elsewhere? If you found it elsewhere it should come with its own methods that you should leave alone. If it's your class, then which class are you trying to run?

http://www.acme.com/resources/classes/Acme/MainFrame.java can help you run an applet as part of an application.

[Anthony Schmitt]

de.mud.jta.Applet is part of the JTA .jar. My understanding of it is that de.mud.jta.Applet does a lot of the stuff you would need to do yourself in your JFrame otherwise.

I'm trying to call Applet.class which will run numerous other classes once it's been correctly called.

The .jar is included in the build, libraries, and all that by the way.

[Tim Moores]

What you posted does not look like a functional applet - it doesn't have operational start, stop and init methods, nor a constructor. Where does that code come from, and what does it have to do with the problem at hand?

[Anthony Schmitt]

I think I see what I'm doing wrong. Applet.class has methods. Just because I'm making an instance of the class doesn't mean I'm callng the methods.

So, adding init(); and start(); to JInternal Frame, I get a NullPointerException here:

     public String getParameter(String name) {
         return stub.getParameter(name);
     }

[Anthony Schmitt]

OK, OK! So posting all of this has gotten me thinking. (I'm pretty new to this, can you tell?) I have a JTA jar and a JTA developer's JAR, and looking at Applet.java it's VERY different than Applet.class! Perhaps I need to include the developer jar in my libraries and build and call this instead?

/**
 * <B>JTA - Telnet/SSH for the JAVA(tm) platform: Applet</B><P>
 * This is the implementation of whole set of applications. It's modular
 * structure allows to configure the software to act either as a sophisticated
 * terminal emulation and/or, adding the network backend, as telnet
 * implementation. Additional modules provide features like scripting or an
 * improved graphical user interface.<P>
 * This software is written entirely in Java<SUP>tm</SUP>.<P>
 * This is the <I>Applet</I> implementation for the software. It initializes
 * the system and adds all needed components, such as the telnet backend and
 * the terminal front end.
 * <P>
 * <B>Maintainer:</B> Matthias L. Jugel
 *
 * @version $Id: Applet.java 499 2005-09-29 08:24:54Z leo $
 * @author Matthias L. Jugel, Marcus Meissner
 */
public class Applet extends JApplet {

  private final static int debug = 0;

  private String frameTitle = null;
  private RootPaneContainer appletFrame;

  /** holds the defaults */
  private Properties options = new Properties();

  /** hold the common part of the jta */
  private Common pluginLoader;

  /** hold the host and port for our connection */
  private String host, port;

  /** disconnect on leave, this is to force applets to break the connection */
  private boolean disconnect = true;
  /** connect on startup, this is to force applets to connect on detach */
  private boolean connect = false;
  /** close the window (if it exists) after the connection is lost */
  private boolean disconnectCloseWindow = true;

  private Plugin focussedPlugin;
  private Clipboard clipboard;
  private boolean online = false;

  /**
   * Read all parameters from the applet configuration and
   * do initializations for the plugins and the applet.
   */
  public void init() {
    if (debug > 0) System.err.println("Applet: init()");
    if (pluginLoader == null) {
      try {
        options.load(Applet.class
                     .getResourceAsStream("/de/mud/jta/default.conf"));
      } catch (Exception e) {
        try {
          URL url = new URL(getCodeBase() + "default.conf");
          options.load(url.openStream());
        } catch (Exception e1) {
          System.err.println("jta: cannot load default.conf");
          System.err.println("jta: try extracting it from the jar file");
          System.err.println("jta: expected file here: "
                             + getCodeBase() + "default.conf");
        }
      }

      String value;

      // try to load the local configuration and merge it with the defaults
      if ((value = getParameter("config")) != null) {
        Properties appletParams = new Properties();
        URL url = null;
        try {
          url = new URL(value);
        } catch (Exception e) {
          try {
            url = new URL(getCodeBase() + value);
          } catch (Exception ce) {
            System.err.println("jta: could not find config file: " + ce);
          }
        }

        if (url != null) {
          try {
            appletParams.load(Applet.class.getResourceAsStream("/de/mud/jta/" + value));
            Enumeration ape = appletParams.keys();
            while (ape.hasMoreElements()) {
              String key = (String) ape.nextElement();
              options.put(key, appletParams.getProperty(key));
            }
          } catch (Exception e) {
            try {
              appletParams.load(url.openStream());
              Enumeration ape = appletParams.keys();
              while (ape.hasMoreElements()) {
                String key = (String) ape.nextElement();
                options.put(key, appletParams.getProperty(key));
              }
            } catch (Exception e2) {
              System.err.println("jta: could not load config file: " + e2);
            }
          }
        }
      }

      // see if there are parameters in the html to override properties
      parameterOverride(options);

      // configure the application and load all plugins
      pluginLoader = new Common(options);

      // set the host to our code base, no other hosts are allowed anyway
      host = options.getProperty("Socket.host");
      if (host == null)
        host = getCodeBase().getHost();
      port = options.getProperty("Socket.port");
      if (port == null)
        port = "23";

      if ((new Boolean(options.getProperty("Applet.connect"))
              .booleanValue()))
        connect = true;
      if (!(new Boolean(options.getProperty("Applet.disconnect"))
              .booleanValue()))
        disconnect = false;

      if (!(new Boolean(options.getProperty("Applet.disconnect.closeWindow"))
              .booleanValue()))
        disconnectCloseWindow = false;

      frameTitle = options.getProperty("Applet.detach.title");

      if ((new Boolean(options.getProperty("Applet.detach"))).booleanValue()) {
        if (frameTitle == null) {
          appletFrame = (RootPaneContainer)new JFrame("jta: " + host + (port.equals("23")?"":" " + port));
        } else {
          appletFrame = (RootPaneContainer)new JFrame(frameTitle);
        }
      } else {
        appletFrame = (RootPaneContainer)this;
      }
      appletFrame.getContentPane().setLayout(new BorderLayout());

      Map componentList = pluginLoader.getComponents();
      Iterator names = componentList.keySet().iterator();
      while (names.hasNext()) {
        String name = (String) names.next();
        Component c = (Component) componentList.get(name);
        if ((value = options.getProperty("layout." + name)) != null) {
          appletFrame.getContentPane().add(value, c);
        } else {
          System.err.println("jta: no layout property set for '" + name + "'");
          System.err.println("jta: ignoring '" + name + "'");
        }
      }

      pluginLoader.registerPluginListener(new SoundListener() {
        public void playSound(URL audioClip) {
          Applet.this.getAudioClip(audioClip).play();
        }
      });

      pluginLoader.broadcast(new AppletRequest(this));
      if (appletFrame != this) {
        final String startText = options.getProperty("Applet.detach.startText");
        final String stopText = options.getProperty("Applet.detach.stopText");
        final Button close = new Button();

        // this works for Netscape only!
        Vector privileges =
                Common.split(options.getProperty("Applet.Netscape.privilege"), ',');
        Class privilegeManager = null;
        Method enable = null;
        try {
          privilegeManager =
                  Class.forName("netscape.security.PrivilegeManager");
          enable = privilegeManager
                  .getMethod("enablePrivilege", new Class[]{String.class});
        } catch (Exception e) {
          System.err.println("Applet: This is not Netscape ...");
        }

        if (privilegeManager != null && enable != null && privileges != null)
          for (int i = 0; i < privileges.size(); i++)
            try {
              enable.invoke(privilegeManager,
                            new Object[]{privileges.elementAt(i)});
              System.out.println("Applet: access for '" +
                                 privileges.elementAt(i) + "' allowed");

            } catch (Exception e) {
              System.err.println("Applet: access for '" +
                                 privileges.elementAt(i) + "' denied");
            }

        // set up the clipboard
        try {
          clipboard = appletFrame.getContentPane().getToolkit().getSystemClipboard();
          System.err.println("Applet: acquired system clipboard: " + clipboard);
        } catch (Exception e) {
          System.err.println("Applet: system clipboard access denied: " +
                             ((e instanceof InvocationTargetException) ?
                              ((InvocationTargetException) e).getTargetException() : e));
          // e.printStackTrace();
        } finally {
          if (clipboard == null) {
            System.err.println("Applet: copy & paste only within the JTA");
            clipboard = new Clipboard("de.mud.jta.Main");
          }
        }

        if ((new Boolean(options.getProperty("Applet.detach.immediately"))
                .booleanValue())) {
          if ((new Boolean(options.getProperty("Applet.detach.fullscreen"))
                  .booleanValue()))
            ((JFrame) appletFrame)
                    .setSize(appletFrame.getContentPane().getToolkit().getScreenSize());
          else
            ((JFrame) appletFrame).pack();

          ((JFrame) appletFrame).show();
          pluginLoader.broadcast(new SocketRequest(host, Integer.parseInt(port)));
          pluginLoader.broadcast(new ReturnFocusRequest());
          close.setLabel(startText != null ? stopText : "Disconnect");
        } else
          close.setLabel(startText != null ? startText : "Connect");

        close.addActionListener(new ActionListener() {
          public void actionPerformed(ActionEvent evt) {
            if (((JFrame) appletFrame).isVisible()) {
              pluginLoader.broadcast(new SocketRequest());
              ((JFrame) appletFrame).setVisible(false);
              close.setLabel(startText != null ? startText : "Connect");
            } else {
              if (frameTitle == null)
                ((JFrame) appletFrame)
                        .setTitle("jta: " + host + (port.equals("23")?"":" " + port));
              if ((new Boolean(options.getProperty("Applet.detach.fullscreen"))
                      .booleanValue()))
                ((JFrame) appletFrame)
                        .setSize(appletFrame.getContentPane().getToolkit().getScreenSize());
              else
                ((JFrame) appletFrame).pack();
              ((JFrame) appletFrame).show();
              if (port == null || port.length() <= 0)
		port = "23";
              getAppletContext().showStatus("Trying " + host + " " + port + " ...");
              pluginLoader.broadcast(new SocketRequest(host,
                                                       Integer.parseInt(port)));
              pluginLoader.broadcast(new ReturnFocusRequest());
              close.setLabel(stopText != null ? stopText : "Disconnect");
            }
          }
        });

        getContentPane().setLayout(new BorderLayout());
        getContentPane().add("Center", close);

        // add a menu bar
        MenuBar mb = new MenuBar();
        Menu file = new Menu("File");
        file.setShortcut(new MenuShortcut(KeyEvent.VK_F, true));
        MenuItem tmp;
        file.add(tmp = new MenuItem("Connect"));
        tmp.addActionListener(new ActionListener() {
          public void actionPerformed(ActionEvent evt) {
            pluginLoader.broadcast(new SocketRequest(host,
                                                     Integer.parseInt(port)));
          }
        });
        file.add(tmp = new MenuItem("Disconnect"));
        tmp.addActionListener(new ActionListener() {
          public void actionPerformed(ActionEvent evt) {
            pluginLoader.broadcast(new SocketRequest());
          }
        });
        file.add(new MenuItem("-"));
        file.add(tmp = new MenuItem("Print"));
        tmp.addActionListener(new ActionListener() {
          public void actionPerformed(ActionEvent evt) {
            if (pluginLoader.getComponents().get("Terminal") != null) {
              PrintJob printJob =
                      appletFrame.getContentPane().getToolkit()
                      .getPrintJob((JFrame) appletFrame, "JTA Terminal", null);
              ((Component) pluginLoader.getComponents().get("Terminal"))
                      .print(printJob.getGraphics());
              printJob.end();
            }
          }
        });
        file.add(new MenuItem("-"));
        file.add(tmp = new MenuItem("Exit"));
        tmp.addActionListener(new ActionListener() {
          public void actionPerformed(ActionEvent evt) {
            ((JFrame) appletFrame).setVisible(false);
            pluginLoader.broadcast(new SocketRequest());
            close.setLabel(startText != null ? startText : "Connect");
          }
        });
        mb.add(file);

        Menu edit = new Menu("Edit");
        edit.setShortcut(new MenuShortcut(KeyEvent.VK_E, true));
        edit.add(tmp = new MenuItem("Copy"));
        tmp.addActionListener(new ActionListener() {
          public void actionPerformed(ActionEvent evt) {
            if (debug > 2)
              System.err.println("Applet: copy: " + focussedPlugin);
            if (focussedPlugin instanceof VisualTransferPlugin)
              ((VisualTransferPlugin) focussedPlugin).copy(clipboard);
          }
        });
        edit.add(tmp = new MenuItem("Paste"));
        tmp.addActionListener(new ActionListener() {
          public void actionPerformed(ActionEvent evt) {
            if (debug > 2)
              System.err.println("Applet: paste: " + focussedPlugin);
            if (focussedPlugin instanceof VisualTransferPlugin)
              ((VisualTransferPlugin) focussedPlugin).paste(clipboard);
          }
        });
        mb.add(edit);

        Map menuList = pluginLoader.getMenus();
        names = menuList.keySet().iterator();
        while (names.hasNext()) {
          String name = (String) names.next();
	  Object o = menuList.get(name);
          if (o instanceof Menu) mb.add((Menu) o);
        }

        Menu help = new Menu("Help");
        help.setShortcut(new MenuShortcut(KeyEvent.VK_HELP, true));
        help.add(tmp = new MenuItem("General"));
        tmp.addActionListener(new ActionListener() {
          public void actionPerformed(ActionEvent e) {
            Help.show(appletFrame.getContentPane(), options.getProperty("Help.url"));
          }
        });
        mb.setHelpMenu(help);

        // only add the menubar if the property is true
        if ((new Boolean(options.getProperty("Applet.detach.menuBar"))
                .booleanValue()))
          ((JFrame) appletFrame).setMenuBar(mb);

        // add window closing event handler
        try {
          ((JFrame) appletFrame).addWindowListener(new WindowAdapter() {
            public void windowClosing(WindowEvent evt) {
              pluginLoader.broadcast(new SocketRequest());
              ((JFrame) appletFrame).setVisible(false);
              close.setLabel(startText != null ? startText : "Connect");
            }
          });
        } catch (Exception e) {
          System.err.println("Applet: could not set up Window event listener");
          System.err.println("Applet: you will not be able to close it");
        }

        pluginLoader.registerPluginListener(new OnlineStatusListener() {
          public void online() {
            if (debug > 0) System.err.println("Terminal: online");
            online = true;
            if (((JFrame) appletFrame).isVisible() == false)
              ((JFrame) appletFrame).setVisible(true);
          }

          public void offline() {
            if (debug > 0) System.err.println("Terminal: offline");
            online = false;
            if (disconnectCloseWindow) {
              ((JFrame) appletFrame).setVisible(false);
              close.setLabel(startText != null ? startText : "Connect");
            }
          }
        });

        // register a focus status listener, so we know when a plugin got focus
        pluginLoader.registerPluginListener(new FocusStatusListener() {
          public void pluginGainedFocus(Plugin plugin) {
            if (Applet.debug > 0)
              System.err.println("Applet: " + plugin + " got focus");
            focussedPlugin = plugin;
          }

          public void pluginLostFocus(Plugin plugin) {
            // we ignore the lost focus
            if (Applet.debug > 0)
              System.err.println("Applet: " + plugin + " lost focus");
          }
        });

      } else
      // if we have no external frame use this online status listener
        pluginLoader.registerPluginListener(new OnlineStatusListener() {
          public void online() {
            if (debug > 0) System.err.println("Terminal: online");
            online = true;
          }

          public void offline() {
            if (debug > 0) System.err.println("Terminal: offline");
            online = false;
          }
        });


    }
  }

  /**
   * Start the applet. Connect to the remote host.
   */
  public void start() {
    if (!online && (appletFrame == this || connect)) {
      if (debug > 0) System.err.println("start(" + host + ", " + port + ")");
      getAppletContext().showStatus("Trying " + host + " " + port + " ...");
      pluginLoader.broadcast(new SocketRequest(host, Integer.parseInt(port)));
      pluginLoader.broadcast(new ReturnFocusRequest());
    }
  }

  /**
   * Stop the applet and disconnect.
   */
  public void stop() {
    if (online && disconnect) {
      if (debug > 0) System.err.println("stop()");
      pluginLoader.broadcast(new SocketRequest());
    }
  }

  /**
   * Override any properties that are found in the configuration files
   * with possible values found as applet parameters.
   * @param options the loaded configuration file properties
   */
  private void parameterOverride(Properties options) {
    Enumeration e = options.keys();
    while (e.hasMoreElements()) {
      String key = (String) e.nextElement(), value = getParameter(key);
      if (value != null) {
        System.out.println("Applet: overriding value of " + key + " with " + value);
        // options.setProperty(key, value);
        options.put(key, value);
      }
    }
  }
}

[Paul Clapham]

Anthony Schmitt wrote:Perhaps I need to include the developer jar in my libraries and build and call this instead?

Yup. That's what the jar is for. Just put it in your application's classpath and use its classes as you see fit.

[Tim Moores]

I still recommend you look at the link I posted. Even if you end up not using that class, it will give you an idea of how to embed an applet in an application (like, from where and when to call the applet lifecycle methods).

[Anthony Schmitt]

So I include BOTH the basic JTA and JTA-SOURCE Jars in my build?

I took out JTA and replaced it with the source jar, now import can't find de.mud.jta.*;

[Paul Clapham]

Anthony Schmitt wrote:So I include BOTH the basic JTA and JTA-SOURCE Jars in my build?

My guess, based solely on the names of the jars, is that JTA-SOURCE contains the source code and that JTA contains the compiled classes.

I took out JTA and replaced it with the source jar, now import can't find de.mud.jta.*;

Which confirms my guess.

[Anthony Schmitt]

You are correct, Paul.

Sadly, I'm still not any closer to getting the applet to run in my JInternalFrame.

[Anthony Schmitt]

I think this is failing because it's trying to get info from a config file... this is where I get the nullpointer:

    /**
     * Returns the value of the named parameter in the HTML tag. For
     * example, if this applet is specified as
     * <blockquote><pre>
     * <applet code="Clock" width=50 height=50>
     * <param name=Color value="blue">
     * </applet>
     * </pre></blockquote>
     * <p>
     * then a call to <code>getParameter("Color")</code> returns the
     * value <code>"blue"</code>.
     * <p>
     * The <code>name</code> argument is case insensitive.
     *
     * @param   name   a parameter name.
     * @return  the value of the named parameter,
     *          or <code>null</code> if not set.
     */
     public String getParameter(String name) {
         return stub.getParameter(name);
     }