My opinion is that the plugin.xml implementation is the way to go.
My main two reasons for using this method:
- It's really easy to reconfigure and reorganize the menus and buttons without writing java code.
- Very clear hierarchical visualization of the menu trees.
Here is a code snippet that implements menus and submenus. In this example, they are added to the main menu.
You can paste this into your plugin.xml:
<extension
name="Main Menu Contributions"
point="org.eclipse.ui.menus">
<menuContribution
allPopups="false"
locationURI="menu:org.eclipse.ui.main.menu">
<menu
id="fileMenu"
label="File">
<command
commandId="org.eclipse.ui.file.exit"
label="Exit"
style="push">
</command>
</menu>
<menu
label="Edit">
<command
commandId="org.eclipse.ui.edit.selectAll"
label="Select All"
style="push">
</command>
<menu
label="Submenu">
<command
commandId="org.eclipse.ui.edit.selectAll"
label="Select All Submenu"
style="push">
</command>
<command
commandId="org.eclipse.ui.edit.delete"
label="Delete submenu"
style="push">
</command>
</menu>
</menu>
</menuContribution>
</extension>
For activating/deactivating a menu, you have to use Core Expressions to enable/disable command handlers. If a command doesn't have any active handlers attached, it will be disabled. So, the menu item that calls that command will also be disabled.
The following code snippets show how to create a button on the toolbar of a view and have it be enabled/disabled depending of a variable's value. Bare in mind that you will have to change some things in this code to make it work. Most of the changes are for reference names and class implementation.
Create the button in the toolbar (plugin.xml):
<extension
name="View Toolbar Contributions"
point="org.eclipse.ui.menus">
<menuContribution
allPopups="false"
locationURI="toolbar:myapp.views.MyView">
<command
commandId="myapp.commands.PauseSound"
icon=""
label="Pause Playback Sound"
style="push"
tooltip="Pause">
</command>
</menuContribution>
</extension>
Create the command (plugin.xml):
<extension
id="myapp.commands.PauseSound"
name="Pause sound command"
point="org.eclipse.ui.commands">
<command
id="myapp.commands.PauseSound"
name="Pause Sound">
</command>
</extension>
Create the command handler (plugin.xml):
<extension
point="org.eclipse.ui.handlers">
<handler
commandId="myapp.commands.PauseSound">
<activeWhen>
<with
variable="myapp.commands.sourceprovider.active">
<or>
<equals
value="PLAYING">
</equals>
<equals
value="PAUSED">
</equals>
</or>
</with>
</activeWhen>
<class
class="myapp.rcp.commands.toolbar.PausePlayback">
</class>
</handler>
</extension>
Create the state variable for the command (plugin.xml):
<extension
point="org.eclipse.ui.services">
<sourceProvider
provider="myapp.commands.sourceprovider.CommandState">
<variable
name="myapp.commands.sourceprovider.active"
priorityLevel="workbench">
</variable>
</sourceProvider>
</extension>
Implement the class that changes the variable's state:
public class CommandState extends AbstractSourceProvider {
public final static String STATE = "myapp.commands.sourceprovider.active";
public final static String STOPPED = "STOPPED";
public final static String PLAYING = "PLAYING";
public final static String PAUSED = "PAUSED";
public final static String NOT_LOADED = "NOT_LOADED";
enum State {
NOT_LOADED, PLAYING, PAUSED, STOPPED
};
private State curState = State.NOT_LOADED;
@Override
public void dispose() {
}
@Override
public String[] getProvidedSourceNames() {
return new String[] { STATE };
}
// You cannot return NULL
@SuppressWarnings("unchecked")
@Override
public Map getCurrentState() {
Map map = new HashMap(1);
if (curState == State.PLAYING)
map.put(STATE, PLAYING);
else if (curState == State.STOPPED)
map.put(STATE, STOPPED);
else if (curState == State.PAUSED)
map.put(STATE, PAUSED);
return map;
}
public void setPlaying() {
fireSourceChanged(ISources.WORKBENCH, STATE, PLAYING);
}
public void setPaused() {
fireSourceChanged(ISources.WORKBENCH, STATE, PAUSED);
}
public void setStopped() {
fireSourceChanged(ISources.WORKBENCH, STATE, STOPPED);
}
public void setNotLoaded() {
fireSourceChanged(ISources.WORKBENCH, STATE, NOT_LOADED);
}
}
More details on how to implement these features can be found at these locations: