vogella.de

This chapter explains how to extend existing UI elements using the example of the package explorer. The context menu is displayed if the user select a file in the package explorer via a right mouse click. We will offer the option to create a HTML page for a Java source file. file.

To contribute to an existing menu or toolbar you need to know the corresponding ID. This ID can be found via the "Menu Spy". See Eclipse Source Code Guide for details.

The following uses Eclipse Commands. See Eclipse Commands to learn how to work with commands.

Create a new plugin project "de.vogella.plugin.htmlconverter". Do not use a template. Select the tab "Dependencies" of your "plugin.xml". Add the dependencies to "org.eclipse.jdt.core" "org.eclipse.core.resources".

Add a command with the ID "de.vogella.plugin.htmlconverter.convert" and the default handler "de.vogella.plugin.htmlconverter.handler.Convert" to your plugin. Add this command to the menu via the extension point "org.eclipse.ui.menus" and use as the "locationURI" "popup:org.eclipse.jdt.ui.PackageExplorer". Set the label to "Create HTML" for this contribution. The resulting "plugin.xml" should look like the following.

				
<?xml version="1.0" encoding="UTF-8"?>
<?eclipse version="3.4"?>
<plugin>
   <extension
         point="org.eclipse.ui.menus">
      <menuContribution
            locationURI="popup:org.eclipse.jdt.ui.PackageExplorer">
         <command
               commandId="de.vogella.plugin.htmlconverter.convert"
               label="Create HTML"
               style="push">
         </command>
      </menuContribution>
   </extension>
   <extension
         point="org.eclipse.ui.commands">
      <command
            defaultHandler="de.vogella.plugin.htmlconverter.handler.Convert"
            id="de.vogella.plugin.htmlconverter.convert"
            name="Convert">
      </command>
   </extension>

</plugin>

			

Create the class "de.vogella.plugin.htmlconverter.handler.Convert" Eclipse allows to save additional information for each file. You can use the interface "IResource" and the methods "setPersistentProperty()" and "getPersistentProperty()". With these functions you can save Strings on files. We use these functions to save a directory for Java source files which already were exported via HTML.

				
package de.vogella.plugin.htmlconverter.handler;

import java.io.BufferedWriter;
import java.io.FileWriter;
import java.io.IOException;

import org.eclipse.core.commands.AbstractHandler;
import org.eclipse.core.commands.ExecutionEvent;
import org.eclipse.core.commands.ExecutionException;
import org.eclipse.core.resources.IResource;
import org.eclipse.core.runtime.CoreException;
import org.eclipse.core.runtime.QualifiedName;
import org.eclipse.jdt.core.Flags;
import org.eclipse.jdt.core.ICompilationUnit;
import org.eclipse.jdt.core.IMethod;
import org.eclipse.jdt.core.IType;
import org.eclipse.jdt.core.JavaModelException;
import org.eclipse.jface.dialogs.MessageDialog;
import org.eclipse.jface.viewers.IStructuredSelection;
import org.eclipse.swt.widgets.DirectoryDialog;
import org.eclipse.ui.handlers.HandlerUtil;

public class Convert extends AbstractHandler {
	private QualifiedName path = new QualifiedName("html", "path");

	@Override
	public Object execute(ExecutionEvent event) throws ExecutionException {

		IStructuredSelection selection = (IStructuredSelection) HandlerUtil
				.getActiveMenuSelection(event);
		DirectoryDialog fileDialog = new DirectoryDialog(HandlerUtil
				.getActiveShell(event));
		String directory = "";
		Object firstElement = selection.getFirstElement();
		if (firstElement instanceof ICompilationUnit) {
			ICompilationUnit cu = (ICompilationUnit) firstElement;
			IResource res = cu.getResource();
			boolean newDirectory = true;
			directory = getPersistentProperty(res, path);

			if (directory != null && directory.length() > 0) {
				newDirectory = !(MessageDialog.openQuestion(HandlerUtil
						.getActiveShell(event), "Question",
						"Use the previous output directory?"));
			}
			if (newDirectory) {
				directory = fileDialog.open();

			}
			if (directory != null && directory.length() > 0) {
				analyze(cu);
				setPersistentProperty(res, path, directory);
				write(directory, cu);
			}

		} else {
			MessageDialog.openInformation(HandlerUtil.getActiveShell(event),
					"Information", "Please select a Java source file");
		}

		// iterator.next();

		// }
		return null;
	}

	protected String getPersistentProperty(IResource res, QualifiedName qn) {
		try {
			return (String) res.getPersistentProperty(qn);
		} catch (CoreException e) {
			return "";
		}
	}

	// TODO: Include this in the HTML output

	private void analyze(ICompilationUnit cu) {
		// Cool JDT allows you to analyze the code easily
		// I don't see really a use case here but I just wanted to do this here
		// as I consider this as cool and
		// what to have a place where I can store the data
		try {

			IType type = null;
			IType[] allTypes;
			allTypes = cu.getAllTypes();
			/**
			 * Search the public class
			 */
			for (int t = 0; t < allTypes.length; t++) {
				if (Flags.isPublic((allTypes[t].getFlags()))) {
					type = allTypes[t];
					break;
				}
			}

			String classname = type.getFullyQualifiedName();
			IMethod[] methods = type.getMethods();
		} catch (JavaModelException e) {
			e.printStackTrace();
		}

	}

	protected void setPersistentProperty(IResource res, QualifiedName qn,
			String value) {
		try {
			res.setPersistentProperty(qn, value);
		} catch (CoreException e) {
			e.printStackTrace();
		}
	}

	private void write(String dir, ICompilationUnit cu) {
		try {
			cu.getCorrespondingResource().getName();
			String test = cu.getCorrespondingResource().getName();
			// Need
			String[] name = test.split("\\.");
			System.out.println(test);
			System.out.println(name.length);
			String htmlFile = dir + "\\" + name[0] + ".html";

			System.out.println(htmlFile);
			FileWriter output = new FileWriter(htmlFile);
			BufferedWriter writer = new BufferedWriter(output);
			writer.write("<html>");
			writer.write("<head>");
			writer.write("</head>");
			writer.write("<body>");
			writer.write("<pre>");
			writer.write(cu.getSource());
			writer.write("</pre>");
			writer.write("</body>");
			writer.write("</html>");
			writer.flush();
		} catch (JavaModelException e) {
		} catch (IOException e) {
			e.printStackTrace();
		}

	}
}

			

Finished. If you run your plugin you should be able to create HTML output from a Java source code file.

It would be better if the command if only display if a Source file is selected. Add the dependency "org.eclipse.core.expressions" to your plugin. Select your menu contribution. Using the right mouse add the condition to the command that it should only be visible if a file is selected which represents a "org.eclipse.jdt.core.ICompilationUnit". This is a class which can be compiled.

This will result in the following "plugin.xml".

				
<?xml version="1.0" encoding="UTF-8"?>
<?eclipse version="3.4"?>
<plugin>
   <extension
         point="org.eclipse.ui.menus">
      <menuContribution
            locationURI="popup:org.eclipse.jdt.ui.PackageExplorer">
         <command
               commandId="de.vogella.plugin.htmlconverter.convert"
               label="Create HTML"
               style="push">
               <visibleWhen>
               <with
                     variable="activeMenuSelection">
                  <iterate>
                     <adapt
                           type="org.eclipse.jdt.core.ICompilationUnit">
                     </adapt></iterate>
               </with>
            </visibleWhen>
         </command>
      </menuContribution>
   </extension>
   <extension
         point="org.eclipse.ui.commands">
      <command
            defaultHandler="de.vogella.plugin.htmlconverter.handler.Convert"
            id="de.vogella.plugin.htmlconverter.convert"
            name="Convert">
      </command>
   </extension>

</plugin>

			

Eclipse represents Resources like Projects, Files, Folders, Packages as IResource.

Marker represent additional informations for resources, e.g. an error marker. Every marker can have attributes (key / value combination). Markers can be displayed in the standard view, e.g. the Task, Bookmark or the problems view. To be displayed in these views you have to use predefined attributes.

The following will demonstrate how to create marker for a selected resource.

Create a plug-in project "de.vogella.plugin.markers". Add the dependency to org.eclipse.core.resources", "org.eclipse.jdt.core" and "org.eclipse.jdt.ui". Create the command "de.vogella.plugin.markers.AddMarker" with the default handler "de.vogella.plugin.markers.handler.AddMarker" and add this command to the menu.

Create the following code.

				
package de.vogella.plugin.markers.handler;

import org.eclipse.core.commands.AbstractHandler;
import org.eclipse.core.commands.ExecutionEvent;
import org.eclipse.core.commands.ExecutionException;
import org.eclipse.core.resources.IMarker;
import org.eclipse.core.resources.IResource;
import org.eclipse.jdt.core.IJavaProject;
import org.eclipse.jface.viewers.IStructuredSelection;
import org.eclipse.ui.handlers.HandlerUtil;

public class AddMarker extends AbstractHandler {

	@Override
	public Object execute(ExecutionEvent event) throws ExecutionException {
		IStructuredSelection selection = (IStructuredSelection) HandlerUtil
				.getActiveSite(event).getSelectionProvider().getSelection();
		if (selection == null) {
			return null;
		}
		Object firstElement = selection.getFirstElement();
		if (firstElement instanceof IJavaProject) {
			IJavaProject type = (IJavaProject) firstElement;
			try {
				IResource resource = type.getUnderlyingResource();
				IMarker marker = resource.createMarker(IMarker.TASK);
				marker.setAttribute(IMarker.MESSAGE, "This a a task");
				marker.setAttribute(IMarker.PRIORITY, IMarker.PRIORITY_HIGH);
			} catch (Exception e) {
				e.printStackTrace();
			}

		}
		return null;
	}
}

			

If you run you can create a marker in the TODO list if you select a Java project and click your menu entry.

Adapters help to display information about objects in view without having to adjust the existing views. In this example we will create a small view which allows to select objects and use the properties view to display them.

Adapters are used on several places for example you can use an adapter to display your data in the outline view. See Outline View Example for an example how to do this.

We will simple use an adapter to show our data in the property view. Create a new plugin project "de.vogella.plugin.adapter". Use the "Plug-in with a view" template with the following settings.

Add the dependency "org.eclipse.ui.views" in tab dependencies of plugin.xml.

Create the following data model.

				
package de.vogella.plugin.adapter.model;

public class Todo {
	private String summary;
	private String description;
	public String getSummary() {
		return summary;
	}
	public void setSummary(String summary) {
		this.summary = summary;
	}
	public String getDescription() {
		return description;
	}
	public void setDescription(String description) {
		this.description = description;
	}

}

			

Change the code of SampleView.java to the following. After this change you should be able to run your project, open your view and see your todo items.

				
package de.vogella.plugin.adapter.views;

import org.eclipse.jface.viewers.IStructuredContentProvider;
import org.eclipse.jface.viewers.ITableLabelProvider;
import org.eclipse.jface.viewers.LabelProvider;
import org.eclipse.jface.viewers.TableViewer;
import org.eclipse.jface.viewers.Viewer;
import org.eclipse.swt.SWT;
import org.eclipse.swt.graphics.Image;
import org.eclipse.swt.widgets.Composite;
import org.eclipse.ui.ISharedImages;
import org.eclipse.ui.PlatformUI;
import org.eclipse.ui.part.ViewPart;

import de.vogella.plugin.adapter.model.Todo;


public class SampleView extends ViewPart {
	public static final String ID = "de.vogella.plugin.adapter.views.SampleView";

	private TableViewer viewer;

	class ViewContentProvider implements IStructuredContentProvider {
		private Todo[] todos;
		public void inputChanged(Viewer v, Object oldInput, Object newInput) {
			todos = (Todo[]) newInput;
		}

		public void dispose() {
		}

		@Override
		public Object[] getElements(Object inputElement) {
			return todos;
		}

	}

	class ViewLabelProvider extends LabelProvider implements
			ITableLabelProvider {
		public String getColumnText(Object obj, int index) {
			Todo todo = (Todo) obj;
			return todo.getSummary();
		}

		public Image getColumnImage(Object obj, int index) {
			return getImage(obj);
		}

		public Image getImage(Object obj) {
			return PlatformUI.getWorkbench().getSharedImages().getImage(
					ISharedImages.IMG_OBJ_ELEMENT);
		}
	}

	/**
	 * This is a callback that will allow us to create the viewer and initialize
	 * it.
	 */
	public void createPartControl(Composite parent) {
		viewer = new TableViewer(parent, SWT.MULTI | SWT.H_SCROLL
				| SWT.V_SCROLL);
		viewer.setContentProvider(new ViewContentProvider());
		viewer.setLabelProvider(new ViewLabelProvider());
		getSite().setSelectionProvider(viewer);
		viewer.setInput(getElements());

	}

	/**
	 * Passing the focus request to the viewer's control.
	 */
	public void setFocus() {
		viewer.getControl().setFocus();
	}
	
	// Build up a simple data model
	private Todo[] getElements() {
		Todo[] todos = new Todo[2];
		Todo todo = new Todo();
		todo.setSummary("First Todo");
		todo.setDescription("A very good description");
		todos[0] = todo;
		todo = new Todo();
		todo.setSummary("Second Todo");
		todo.setDescription("Second super description");
		todos[1] = todo;
		return todos;
	}
}

			

To displays its values in the property view, add the extension point "org.eclipse.core.runtime.adapters" to your project. The data of the extension point should be like the following.

				
<extension
         point="org.eclipse.core.runtime.adapters">
      <factory
            adaptableType="de.vogella.plugin.adapter.model.Todo"
            class="de.vogella.plugin.adapter.TodoAdapterFactory">
         <adapter
               type="org.eclipse.ui.views.properties.IPropertySource">
         </adapter>
      </factory>
</extension>

			

Implement the factory and the new class "TodoPropertySource" which implements "IPropertySource".

				
package de.vogella.plugin.adapter;

import org.eclipse.core.runtime.IAdapterFactory;
import org.eclipse.ui.views.properties.IPropertySource;

import de.vogella.plugin.adapter.model.Todo;

public class TodoAdapterFactory implements IAdapterFactory {

	@Override
	public Object getAdapter(Object adaptableObject, Class adapterType) {
		if (adapterType== IPropertySource.class && adaptableObject instanceof Todo){
			return new TodoPropertySource((Todo) adaptableObject);
		}
		return null;
	}

	@Override
	public Class[] getAdapterList() {
		return new Class[] { IPropertySource.class };
	}

}

			

				
package de.vogella.plugin.adapter;

import org.eclipse.ui.views.properties.IPropertyDescriptor;
import org.eclipse.ui.views.properties.IPropertySource;
import org.eclipse.ui.views.properties.TextPropertyDescriptor;

import de.vogella.plugin.adapter.model.Todo;

public class TodoPropertySource implements IPropertySource {

	private final Todo todo;

	public TodoPropertySource(Todo todo) {
		this.todo = todo;
	}


	@Override
	public boolean isPropertySet(Object id) {
		return false;
	}

	@Override
	public Object getEditableValue() {
		return this;
	}

	@Override
	public IPropertyDescriptor[] getPropertyDescriptors() {

		return new IPropertyDescriptor[] {
				new TextPropertyDescriptor("summary", "Summary"),
				new TextPropertyDescriptor("description", "Description") };
	}

	@Override
	public Object getPropertyValue(Object id) {
		if (id.equals("summary")) {
			return todo.getSummary();
		}
		if (id.equals("description")) {
			return todo.getDescription();
		}
		return null;
	}

	@Override
	public void resetPropertyValue(Object id) {

	}

	@Override
	public void setPropertyValue(Object id, Object value) {
		String s = (String) value;
		if (id.equals("summary")) {
			todo.setSummary(s);
		}
		if (id.equals("description")) {
			todo.setDescription(s);
		}
	}

}

			

If you run your workbench and open your View via Windows -> Show View -> Others -> Sample Category -> Sample View and the property view you should be able to view your data.

Source Code of Examples

http://www.eclipse.org/articles/article.php?file=Article-Adapters/index.html Adapters in Eclipse

http://www.eclipse.org/articles/Article-Resource-deltas/resource-deltas.html How to react to Eclipse resource deltas

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