Java tutorial
/******************************************************************************* * Copyright (c) 2008, 2018 Matthew Hall and others. * * This program and the accompanying materials * are made available under the terms of the Eclipse Public License 2.0 * which accompanies this distribution, and is available at * https://www.eclipse.org/legal/epl-2.0/ * * SPDX-License-Identifier: EPL-2.0 * * Contributors: * IBM Corporation - initial API and implementation * (through WizardPageSupport.java) * Matthew Hall - initial API and implementation (bug 239900) * Matthew Hall - bugs 237856, 275058, 278550 * Ovidio Mallo - bugs 237856, 248877 ******************************************************************************/ package org.eclipse.jface.databinding.dialog; import org.eclipse.core.databinding.DataBindingContext; import org.eclipse.core.databinding.ValidationStatusProvider; import org.eclipse.core.databinding.observable.IChangeListener; import org.eclipse.core.databinding.observable.IObservable; import org.eclipse.core.databinding.observable.IStaleListener; import org.eclipse.core.databinding.observable.ObservableTracker; import org.eclipse.core.databinding.observable.StaleEvent; import org.eclipse.core.databinding.observable.list.IListChangeListener; import org.eclipse.core.databinding.observable.list.IObservableList; import org.eclipse.core.databinding.observable.list.ListChangeEvent; import org.eclipse.core.databinding.observable.list.ListDiffEntry; import org.eclipse.core.databinding.observable.value.IObservableValue; import org.eclipse.core.databinding.util.Policy; import org.eclipse.core.runtime.IStatus; import org.eclipse.core.runtime.MultiStatus; import org.eclipse.core.runtime.Status; import org.eclipse.jface.dialogs.DialogPage; import org.eclipse.jface.dialogs.IMessageProvider; import org.eclipse.swt.SWT; /** * Connects the validation result from the given data binding context to the * given dialog page, updating the page's error message accordingly. * * @since 1.3 */ public class DialogPageSupport { /** * Connect the validation result from the given data binding context to the * given dialog page. The page's error message will not be set at time of * creation, ensuring that the dialog page does not show an error right * away. Upon any validation result change, the dialog page's error message * will be updated according to the current validation result. * * @param dialogPage the dialog page to show validation errors on * @param dbc the binding context to connect * @return an instance of WizardPageSupport */ public static DialogPageSupport create(DialogPage dialogPage, DataBindingContext dbc) { return new DialogPageSupport(dialogPage, dbc); } private DialogPage dialogPage; private DataBindingContext dbc; private IValidationMessageProvider messageProvider = new ValidationMessageProvider(); private IObservableValue<ValidationStatusProvider> aggregateStatusProvider; private boolean uiChanged = false; private IChangeListener uiChangeListener = event -> handleUIChanged(); private IListChangeListener<ValidationStatusProvider> validationStatusProvidersListener = new IListChangeListener<ValidationStatusProvider>() { @Override public void handleListChange(ListChangeEvent<? extends ValidationStatusProvider> event) { for (ListDiffEntry<? extends ValidationStatusProvider> listDiffEntry : event.diff.getDifferences()) { IObservableList<IObservable> targets = listDiffEntry.getElement().getTargets(); if (listDiffEntry.isAddition()) { targets.addListChangeListener(validationStatusProviderTargetsListener); for (IObservable observable : targets) { observable.addChangeListener(uiChangeListener); } } else { targets.removeListChangeListener(validationStatusProviderTargetsListener); for (IObservable observable : targets) { observable.removeChangeListener(uiChangeListener); } } } } }; private IListChangeListener<IObservable> validationStatusProviderTargetsListener = new IListChangeListener<IObservable>() { @Override public void handleListChange(ListChangeEvent<? extends IObservable> event) { for (ListDiffEntry<? extends IObservable> listDiffEntry : event.diff.getDifferences()) { if (listDiffEntry.isAddition()) { listDiffEntry.getElement().addChangeListener(uiChangeListener); } else { listDiffEntry.getElement().removeChangeListener(uiChangeListener); } } } }; private ValidationStatusProvider currentStatusProvider; protected IStatus currentStatus; protected boolean currentStatusStale; /** * @param dialogPage the dialog page to show validation errors on * @param dbc the binding context to connect * @noreference This constructor is not intended to be referenced by * clients. */ protected DialogPageSupport(DialogPage dialogPage, DataBindingContext dbc) { this.dialogPage = dialogPage; this.dbc = dbc; init(); } /** * Sets the {@link IValidationMessageProvider} to use for providing the * message text and message type to display on the dialog page. * * @param messageProvider * The {@link IValidationMessageProvider} to use for providing * the message text and message type to display on the dialog * page. * * @since 1.4 */ public void setValidationMessageProvider(IValidationMessageProvider messageProvider) { this.messageProvider = messageProvider; handleStatusChanged(); } /** * @return the dialog page * @noreference This method is not intended to be referenced by clients. */ protected DialogPage getDialogPage() { return dialogPage; } /** * @noreference This method is not intended to be referenced by clients. */ protected void init() { ObservableTracker.setIgnore(true); try { aggregateStatusProvider = new MaxSeverityValidationStatusProvider(dbc); } finally { ObservableTracker.setIgnore(false); } aggregateStatusProvider.addValueChangeListener(event -> statusProviderChanged()); dialogPage.getShell().addListener(SWT.Dispose, event -> dispose()); aggregateStatusProvider.addStaleListener(new IStaleListener() { @Override public void handleStale(StaleEvent staleEvent) { currentStatusStale = true; handleStatusChanged(); } }); statusProviderChanged(); dbc.getValidationStatusProviders().addListChangeListener(validationStatusProvidersListener); for (ValidationStatusProvider validationStatusProvider : dbc.getValidationStatusProviders()) { IObservableList<IObservable> targets = validationStatusProvider.getTargets(); targets.addListChangeListener(validationStatusProviderTargetsListener); for (IObservable observable : targets) { observable.addChangeListener(uiChangeListener); } } } private void statusProviderChanged() { currentStatusProvider = aggregateStatusProvider.getValue(); if (currentStatusProvider != null) { currentStatus = currentStatusProvider.getValidationStatus().getValue(); } else { currentStatus = null; } currentStatusStale = aggregateStatusProvider.isStale(); handleStatusChanged(); } /** * @noreference This method is not intended to be referenced by clients. */ protected void handleUIChanged() { uiChanged = true; if (currentStatus != null) { handleStatusChanged(); } dbc.getValidationStatusProviders().removeListChangeListener(validationStatusProvidersListener); for (ValidationStatusProvider provider : dbc.getValidationStatusProviders()) { IObservableList<IObservable> targets = provider.getTargets(); targets.removeListChangeListener(validationStatusProviderTargetsListener); for (IObservable observable : targets) { observable.removeChangeListener(uiChangeListener); } } } /** * @noreference This method is not intended to be referenced by clients. */ protected void handleStatusChanged() { String message = messageProvider.getMessage(currentStatusProvider); int type = messageProvider.getMessageType(currentStatusProvider); if (type == IMessageProvider.ERROR) { dialogPage.setMessage(null); dialogPage.setErrorMessage(uiChanged ? message : null); if (currentStatus != null && currentStatusHasException()) { handleStatusException(); } } else { dialogPage.setErrorMessage(null); dialogPage.setMessage(message, type); } } private boolean currentStatusHasException() { boolean hasException = false; if (currentStatus.getException() != null) { hasException = true; } if (currentStatus instanceof MultiStatus) { MultiStatus multiStatus = (MultiStatus) currentStatus; for (int i = 0; i < multiStatus.getChildren().length; i++) { IStatus status = multiStatus.getChildren()[i]; if (status.getException() != null) { hasException = true; break; } } } return hasException; } /** * @noreference This method is not intended to be referenced by clients. */ protected void handleStatusException() { if (currentStatus.getException() != null) { logThrowable(currentStatus.getException()); } else if (currentStatus instanceof MultiStatus) { MultiStatus multiStatus = (MultiStatus) currentStatus; for (int i = 0; i < multiStatus.getChildren().length; i++) { IStatus status = multiStatus.getChildren()[i]; if (status.getException() != null) { logThrowable(status.getException()); } } } } private void logThrowable(Throwable throwable) { Policy.getLog().log(new Status(IStatus.ERROR, Policy.JFACE_DATABINDING, IStatus.OK, "Unhandled exception: " + throwable.getMessage(), throwable)); //$NON-NLS-1$ } /** * Disposes of this wizard page support object, removing any listeners it * may have attached. */ public void dispose() { if (aggregateStatusProvider != null) aggregateStatusProvider.dispose(); if (dbc != null && !uiChanged) { for (ValidationStatusProvider provider : dbc.getValidationStatusProviders()) { provider.getTargets().removeListChangeListener(validationStatusProviderTargetsListener); for (IObservable observable : provider.getTargets()) { observable.removeChangeListener(uiChangeListener); } } dbc.getValidationStatusProviders().removeListChangeListener(validationStatusProvidersListener); } aggregateStatusProvider = null; dbc = null; uiChangeListener = null; validationStatusProvidersListener = null; validationStatusProviderTargetsListener = null; dialogPage = null; } }