examples/org.eclipse.ui.examples.navigator/src/org/eclipse/ui/examples/navigator/actions/DeletePropertyAction.java

/*******************************************************************************
 * Copyright (c) 2005, 2006 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.ui.examples.navigator.actions;

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.lang.reflect.InvocationTargetException;
import java.util.Properties;

import org.eclipse.core.resources.IFile;
import org.eclipse.core.resources.IResource;
import org.eclipse.core.runtime.CoreException;
import org.eclipse.core.runtime.IProgressMonitor;
import org.eclipse.jface.action.IAction;
import org.eclipse.jface.dialogs.MessageDialog;
import org.eclipse.jface.viewers.ISelection;
import org.eclipse.jface.viewers.IStructuredSelection;
import org.eclipse.jface.viewers.StructuredSelection;
import org.eclipse.swt.widgets.Display;
import org.eclipse.ui.PlatformUI;
import org.eclipse.ui.actions.ActionDelegate;
import org.eclipse.ui.actions.WorkspaceModifyOperation;
import org.eclipse.ui.examples.navigator.PropertiesTreeData;
import org.eclipse.ui.internal.examples.navigator.Activator;

/**
 * A sample action that can delete a PropertiesTreeData item from a property file. 
 * 
 * @since 3.2
 */
public class DeletePropertyAction extends ActionDelegate {
	
	private IStructuredSelection selection = StructuredSelection.EMPTY;

	/* (non-Javadoc)
	 * @see org.eclipse.ui.actions.ActionDelegate#selectionChanged(org.eclipse.jface.action.IAction, org.eclipse.jface.viewers.ISelection)
	 */
	public void selectionChanged(IAction action, ISelection sel) {
		if(sel instanceof IStructuredSelection)
			selection = (IStructuredSelection) sel;
		else 
			selection = StructuredSelection.EMPTY;
	}

	/* (non-Javadoc)
	 * @see org.eclipse.ui.actions.ActionDelegate#run(org.eclipse.jface.action.IAction)
	 */
	public void run(IAction action) {
		  
		WorkspaceModifyOperation deletePropertyOperation = new WorkspaceModifyOperation() {
			/* (non-Javadoc)
			 * @see org.eclipse.ui.actions.WorkspaceModifyOperation#execute(org.eclipse.core.runtime.IProgressMonitor)
			 */
			protected void execute(IProgressMonitor monitor) throws CoreException {
				// In production code, you should always externalize strings, but this is an example.
				monitor.beginTask("Deleting property from selection", 5); //$NON-NLS-1$ 
				try {
					if(selection.size() == 1) {
						
						 Object firstElement = selection.getFirstElement();
						 if(firstElement instanceof PropertiesTreeData) {
							 PropertiesTreeData data = (PropertiesTreeData) firstElement;
							 
							 IFile propertiesFile = data.getFile();
							 monitor.worked(1);
							 
							 if(propertiesFile != null && propertiesFile.isAccessible()) {
								 
								 try {
									// load the model 
									 Properties properties = new Properties();
									 properties.load(propertiesFile.getContents());
									 monitor.worked(1);  
									 
									 // delete the property 
									 properties.remove(data.getName());
									 monitor.worked(1);
									 
									 // persist the model to a temporary storage medium (byte[])
									 ByteArrayOutputStream output = new ByteArrayOutputStream();
									 properties.store(output, null);
									 monitor.worked(1);
									 
									 // set the contents of the properties file 
									 propertiesFile.setContents(
											 			new ByteArrayInputStream(output.toByteArray()), 
											 					IResource.FORCE | IResource.KEEP_HISTORY, monitor);
									 monitor.worked(1);
								} catch (IOException e) {
									 // handle error gracefully 
									Activator.logError(0, "Could not delete property!", e); //$NON-NLS-1$
									MessageDialog.openError(Display.getDefault().getActiveShell(), 
							 				"Error Deleting Property",  //$NON-NLS-1$
							 				"Could not delete property!");   //$NON-NLS-1$
								}
									 
							 } else // shouldn't happen, but handle error condition 
								 MessageDialog.openError(Display.getDefault().getActiveShell(), 
										 				"Error Deleting Property",  //$NON-NLS-1$
										 				"The properties file was not accessible!");   //$NON-NLS-1$
							 
						 } else // shouldn't happen, but handle error condition 
							 MessageDialog.openError(Display.getDefault().getActiveShell(), 
						 				"Error Deleting Property",  //$NON-NLS-1$
						 				"The element that was selected was not of the right type.");   //$NON-NLS-1$
					 } else // shouldn't happen, but handle error condition 
						 MessageDialog.openError(Display.getDefault().getActiveShell(), 
					 				"Error Deleting Property",  //$NON-NLS-1$
					 				"An invalid number of properties were selected.");   //$NON-NLS-1$
				} finally {
					monitor.done();
				}
			}
		};		
		try {
			PlatformUI.getWorkbench().getProgressService().run(true, false, deletePropertyOperation);
		} catch (InvocationTargetException e) { 
			// handle error gracefully			
			Activator.logError(0, "Could not delete property!", e); //$NON-NLS-1$
			MessageDialog.openError(Display.getDefault().getActiveShell(), 
	 				"Error Deleting Property",  //$NON-NLS-1$
	 				"Could not delete property!");   //$NON-NLS-1$
		} catch (InterruptedException e) {
			 // handle error gracefully
			Activator.logError(0, "Could not delete property!", e); //$NON-NLS-1$
			MessageDialog.openError(Display.getDefault().getActiveShell(), 
	 				"Error Deleting Property",  //$NON-NLS-1$
	 				"Could not delete property!");   //$NON-NLS-1$
		}
		 
	}
}