Custom Toolbar and Button for oXygen XML Editor

CustomButtonPlugin.java

package de.mediaversal.oxygen.CustomButton;

import ro.sync.exml.plugin.Plugin;
import ro.sync.exml.plugin.PluginDescriptor;

/**
 * CustomButton demo
 * 
 * @author tofi86
 * @created 2014-01-24
 */
public class CustomButtonPlugin extends Plugin {
	/**
	* The static plugin instance.
	*/
	private static CustomButtonPlugin instance = null;
	
	/**
	* Constructs the plugin.
	* 
	* @param descriptor The plugin descriptor
	*/
	public CustomButtonPlugin(PluginDescriptor descriptor) {
		super(descriptor);
		
		if (instance != null) {
			throw new IllegalStateException("Already instantiated!");
		}
		instance = this;
	}
	  
	/**
	* Get the plugin instance.
	* 
	* @return the shared plugin instance.
	*/
	public static CustomButtonPlugin getInstance() {
		return instance;
	}

}

CustomButtonPluginExtension.java

package de.mediaversal.oxygen.CustomButton;

import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.ArrayList;
import java.util.List;
import javax.swing.JButton;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JOptionPane;
import ro.sync.exml.plugin.workspace.WorkspaceAccessPluginExtension;
import ro.sync.exml.workspace.api.standalone.StandalonePluginWorkspace;
import ro.sync.exml.workspace.api.standalone.ToolbarComponentsCustomizer;
import ro.sync.exml.workspace.api.standalone.ToolbarInfo;

public class CustomButtonPluginExtension implements WorkspaceAccessPluginExtension  {

	@Override
	public void applicationStarted(final StandalonePluginWorkspace pluginWorkspaceAccess) {

		// add new toolbar
		pluginWorkspaceAccess.addToolbarComponentsCustomizer(new ToolbarComponentsCustomizer() {
			@Override
			public void customizeToolbar(final ToolbarInfo toolbarInfo) {

				// if toolbar is our custom toolbar (referenced by ID in plugin.xml)
				if (toolbarInfo.getToolbarID().equals("CustomToolbar")) {

					JButton demoButton = new JButton("Demo Button");
					demoButton.addActionListener(new ActionListener() {
						public void actionPerformed(ActionEvent e) {
							JOptionPane.showMessageDialog(
									new JFrame(),
									"Toolbar ID: " + toolbarInfo.getToolbarID(),
									"Window Title",
									JOptionPane.INFORMATION_MESSAGE
							);
						}
					});

					// Add demoButton to toolbar
					List<JComponent> comps = new ArrayList<JComponent>();
					comps.add(demoButton);
					toolbarInfo.setComponents(comps.toArray(new JComponent[0]));

					// Set toolbar title
					toolbarInfo.setTitle("Custom Demo Toolbar");
				}
			}
		});
	}

	@Override
	public boolean applicationClosing() {
		// 'true' if plugin allows application close
		return true;
	}

}

plugin.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plugin SYSTEM "../plugin.dtd">
<plugin
	id="de.mediaversal.oxygen.CustomButton"
	name="Custom Button for oXygen"
	description="Adds a custom toolbar and a button"
	version="1.0.0"
	vendor="mediaversal"
	class="de.mediaversal.oxygen.CustomButton.CustomButtonPlugin"
	classLoaderType="preferReferencedResources">
	<runtime>
		<library name="lib/CustomButton.jar"/>
	</runtime>
	<extension type="WorkspaceAccess" class="de.mediaversal.oxygen.CustomButton.CustomButtonPluginExtension"/>
	
	<!--The sample toolbar which will present messages from the sample plugin.-->
	<toolbar id="CustomToolbar" initialSide="NORTH" initialRow="1"/>
</plugin>