Eclipse Plugin: how to get the path to the currently selected project

Question

I am writing an Eclipse plugin that will display a menu item in the context menu for a Java Project. I have written the plugin.xml as follows:

<plugin>
   <extension
         point="org.eclipse.ui.menus">
      <menuContribution
            locationURI="popup:org.eclipse.jdt.ui.PackageExplorer">
         <dynamic
               class="uk.co.dajohnston.plugin.classpathswitcher.menu.MenuContribution"
               id="uk.co.dajohnston.plugin.classpathSwitcher.switchMenuContribution">
            <visibleWhen>
               <with
                     variable="activeMenuSelection">
                  <iterate>
                     <adapt
                           type="org.eclipse.jdt.core.IJavaProject">
                     </adapt>
                  </iterate>
                  <count
                        value="1">
                  </count>
               </with>
            </visibleWhen>
         </dynamic>
      </menuContribution>
   </extension>

</plugin>

So I am now trying to write the MenuContribution class which extends CompoundContributionItem so that I can create a dynamic menu and the contents of this menu are going to be based on a set of files that exist in the Java Project's root directory. But I am stuck trying to get the path to the root directory from within the getContributionItems method.

Based on the plugin.xml file I can be guarenteed that the method will only be called if a single Java Project is selected, so all I need to do is get the current selection and then get its absolute path. Any ideas? Or is there a better way to do this?

Answer 1

Since I wrote the previous answer I have written another couple of utility plugins and now have a generic starter for Eclipse Navigator Popups. The files are as follows:

Basic manifest file

MANIFEST.MF

Manifest-Version: 1.0
Bundle-ManifestVersion: 2
Bundle-Name: NavigatorPopup
Bundle-SymbolicName: com.nsd.NavigatorPopup;singleton:=true
Bundle-Version: 1.0.0.1
Bundle-Vendor: NSD
Require-Bundle: org.eclipse.ui,
 org.eclipse.core.resources,
 org.eclipse.core.runtime
Bundle-RequiredExecutionEnvironment: JavaSE-1.6

Basic properties file

build.properties

source.. = src/
output.. = bin/
bin.includes = plugin.xml,\
               META-INF/,\
               .

Plugin file

In particular note how <command commandId=...> of the <menuContribution...> <menu..> in the <extension point="org.eclipse.ui.menus"> extension point links to the <handler commandId=...> in the <extension point="org.eclipse.ui.handlers"> extension point this permits us to link multiple menu contributions to a single handler.

Also of note is the fact that there are multiple locationURI's as these can change from one perspective to another.

plugin.xml

<?xml version="1.0" encoding="UTF-8"?>
<?eclipse version="3.4"?>
<plugin>
    <extension point="org.eclipse.ui.commands">
        <category name="NSD Category" id="com.nsd.NavigatorPopup.commands.category"/>
        <command name="Navigator Popup" categoryId="com.nsd.NavigatorPopup.commands.category" id="com.nsd.NavigatorPopup.commands.navigatorPopupCommand"/>
    </extension>
    <extension point="org.eclipse.ui.handlers">
        <handler commandId="com.nsd.NavigatorPopup.commands.navigatorPopupCommand" class="com.nsd.navigatorpopup.NavigatorPopupHandler"/>
    </extension>
    <extension point="org.eclipse.ui.menus">
        <menuContribution locationURI="popup:org.eclipse.jdt.ui.PackageExplorer?after=additions">
            <menu label="Popup Utilities">
                <command commandId="com.nsd.NavigatorPopup.commands.navigatorPopupCommand" id="com.nsd.NavigatorPopup.menus.navigatorPopupCommand"/>
            </menu>
        </menuContribution>
        <menuContribution locationURI="popup:org.eclipse.ui.navigator.ProjectExplorer#PopupMenu?after=additions">
            <menu label="Popup Utilities">
                <command commandId="com.nsd.NavigatorPopup.commands.navigatorPopupCommand" id="com.nsd.NavigatorPopup.menus.navigatorPopupCommand"/>
            </menu>
        </menuContribution>
    </extension>
</plugin>

To find out more about the plugin for the current selection click on a file and use ALT-SHIFT-F1 for the Plug-in Selection Spy

Use ALT-SHIFT-F2 for the Plug-in Menu Spy. Note press the ALT-SHIFT-F2 combination before right clicking and selecting the popup menu item of interest.

Finally the code for the plug-in.

NavigatorPopupHandler.java

package com.nsd.navigatorpopup;

import org.eclipse.core.commands.AbstractHandler;
import org.eclipse.core.commands.ExecutionEvent;
import org.eclipse.core.commands.ExecutionException;
import org.eclipse.core.resources.IFile;
import org.eclipse.core.resources.IProject;
import org.eclipse.core.resources.IResource;
import org.eclipse.core.runtime.IAdaptable;
import org.eclipse.ui.IWorkbenchPage;
import org.eclipse.ui.IWorkbenchWindow;
import org.eclipse.ui.handlers.HandlerUtil;
import org.eclipse.jface.dialogs.MessageDialog;
import org.eclipse.jface.viewers.ISelection;
import org.eclipse.jface.viewers.ITreeSelection;
import org.eclipse.jface.viewers.TreePath;
import org.eclipse.jface.viewers.TreeSelection;

// ====================================================================================================================
// This handler will obtain the core information about a file from a navigator popup menu
// ====================================================================================================================
public class NavigatorPopupHandler extends AbstractHandler {
    private IWorkbenchWindow window;
    private IWorkbenchPage activePage;

    private IProject theProject;
    private IResource theResource;
    private IFile theFile;

    private String workspaceName;
    private String projectName;
    private String fileName;

    public NavigatorPopupHandler() {
        // Empty constructor
    }

    public Object execute(ExecutionEvent event) throws ExecutionException {
        // Get the project and file name from the initiating event if at all possible
        if(!extractProjectAndFileFromInitiatingEvent(event)) {
            return null;
        }

        // CODE THAT USES THE FILE GOES HERE
        MessageDialog.openInformation(this.window.getShell(), "NavigatorPopup", String.format("File Details.\n\nWorkspace=%s\nProject=%s\nFile=%s", workspaceName, projectName, fileName));

        return null;
    }

    private boolean extractProjectAndFileFromInitiatingEvent(ExecutionEvent event) {
        // ============================================================================================================
        // The execute method of the handler is invoked to handle the event. As we only contribute to Explorer
        // Navigator views we expect to get a selection tree event
        // ============================================================================================================
        this.window = HandlerUtil.getActiveWorkbenchWindow(event);
        // Get the active WorkbenchPage
        this.activePage = this.window.getActivePage();

        // Get the Selection from the active WorkbenchPage page
        ISelection selection = this.activePage.getSelection();
        if(selection instanceof ITreeSelection) {
            TreeSelection treeSelection = (TreeSelection) selection;
            TreePath[] treePaths = treeSelection.getPaths();
            TreePath treePath = treePaths[0];

            // The TreePath contains a series of segments in our usage:
            // o The first segment is usually a project
            // o The last segment generally refers to the file

            // The first segment should be a IProject
            Object firstSegmentObj = treePath.getFirstSegment();
            this.theProject = (IProject) ((IAdaptable) firstSegmentObj).getAdapter(IProject.class);
            if(this.theProject == null) {
                MessageDialog.openError(this.window.getShell(), "Navigator Popup", getClassHierarchyAsMsg(
                                "Expected the first segment to be IAdapatable to an IProject.\nBut got the following class hierarchy instead.", "Make sure to directly select a file.",
                                firstSegmentObj));
                return false;
            }

            // The last segment should be an IResource
            Object lastSegmentObj = treePath.getLastSegment();
            this.theResource = (IResource) ((IAdaptable) lastSegmentObj).getAdapter(IResource.class);
            if(this.theResource == null) {
                MessageDialog.openError(this.window.getShell(), "Navigator Popup", getClassHierarchyAsMsg(
                                "Expected the last segment to be IAdapatable to an IResource.\nBut got the following class hierarchy instead.", "Make sure to directly select a file.",
                                firstSegmentObj));
                return false;
            }

            // As the last segment is an IResource we should be able to get an IFile reference from it
            this.theFile = (IFile) ((IAdaptable) lastSegmentObj).getAdapter(IFile.class);

            // Extract additional information from the IResource and IProject
            this.workspaceName = this.theResource.getWorkspace().getRoot().getLocation().toOSString();
            this.projectName = this.theProject.getName();
            this.fileName = this.theResource.getName();

            return true;
        } else {
            String selectionClass = selection.getClass().getSimpleName();
            MessageDialog.openError(this.window.getShell(), "Unexpected Selection Class", String.format("Expected a TreeSelection but got a %s instead.\nProcessing Terminated.", selectionClass));
        }

        return false;
    }

    @SuppressWarnings("rawtypes")
    private static String getClassHierarchyAsMsg(String msgHeader, String msgTrailer, Object theObj) {
        String msg = msgHeader + "\n\n";

        Class theClass = theObj.getClass();
        while(theClass != null) {
            msg = msg + String.format("Class=%s\n", theClass.getName());
            Class[] interfaces = theClass.getInterfaces();
            for(Class theInterface : interfaces) {
                msg = msg + String.format("    Interface=%s\n", theInterface.getName());
            }
            theClass = theClass.getSuperclass();
        }

        msg = msg + "\n" + msgTrailer;

        return msg;
    }
}

And the result of running the plug-in on its own java file.