Java tutorial
/******************************************************************************* * Copyright (c) 2004, 2009 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 * Daniel Megert daniel_megert@ch.ibm.com Bug 169696 *******************************************************************************/ package org.eclipse.ui.ide.dialogs; import java.nio.charset.Charset; import java.nio.charset.IllegalCharsetNameException; import java.util.List; import org.eclipse.jface.preference.FieldEditor; import org.eclipse.jface.preference.IPreferenceStore; import org.eclipse.osgi.util.NLS; import org.eclipse.swt.SWT; import org.eclipse.swt.events.KeyAdapter; import org.eclipse.swt.events.KeyEvent; import org.eclipse.swt.events.SelectionAdapter; import org.eclipse.swt.events.SelectionEvent; import org.eclipse.swt.layout.GridData; import org.eclipse.swt.layout.GridLayout; import org.eclipse.swt.widgets.Button; import org.eclipse.swt.widgets.Combo; import org.eclipse.swt.widgets.Composite; import org.eclipse.swt.widgets.Group; import org.eclipse.ui.WorkbenchEncoding; import org.eclipse.ui.ide.IDEEncoding; import org.eclipse.ui.internal.ide.IDEWorkbenchMessages; /** * The abstract superclass of field editors used to set an encoding. Any user * entered encodings will be added to the list of encodings available via * {@link org.eclipse.ui.ide.IDEEncoding}. * <p> * Subclasses may extend, but must call <code>createEncodingGroup</code> * during <code>doFillIntoGrid</code>. * </p> * * @see org.eclipse.ui.ide.IDEEncoding * @since 3.1 */ public abstract class AbstractEncodingFieldEditor extends FieldEditor { private Composite container; private Button defaultEncodingButton; private String defaultEnc; private Button otherEncodingButton; private Combo encodingCombo; private boolean isValid = true; private String oldSelectedEncoding; private String groupTitle = IDEWorkbenchMessages.WorkbenchPreference_encoding; /** * Creates a new encoding field editor with no settings set. */ protected AbstractEncodingFieldEditor() { super(); } /** * Creates a new encoding field editor with the given preference name, label * and parent. * * @param name * the name of the preference this field editor works on * @param labelText * the label text of the field editor * @param parent * the parent of the field editor's control */ protected AbstractEncodingFieldEditor(String name, String labelText, Composite parent) { super(name, labelText, parent); } /** * Creates a new encoding field editor with the given preference name, label * and parent. * * @param name * the name of the preference this field editor works on * @param labelText * the label text of the field editor * @param groupTitle * the title for the field editor's control. If groupTitle is * <code>null</code> the control will be unlabelled * (by default a {@link Composite} instead of a {@link Group}. * @param parent * the parent of the field editor's control * @see AbstractEncodingFieldEditor#setGroupTitle(String) * @since 3.3 */ protected AbstractEncodingFieldEditor(String name, String labelText, String groupTitle, Composite parent) { init(name, labelText); this.groupTitle = groupTitle; createControl(parent); } /* * (non-Javadoc) * * @see org.eclipse.jface.preference.FieldEditor#adjustForNumColumns(int) */ protected void adjustForNumColumns(int numColumns) { ((GridData) getContainer().getLayoutData()).horizontalSpan = numColumns; } /* * (non-Javadoc) * * @see org.eclipse.jface.preference.FieldEditor#doFillIntoGrid(org.eclipse.swt.widgets.Composite, * int) */ protected void doFillIntoGrid(Composite parent, int numColumns) { container = createEncodingGroup(parent, numColumns); } /* * (non-Javadoc) * * @see org.eclipse.jface.preference.FieldEditor#doLoad() */ protected void doLoad() { if (encodingCombo != null) { List encodings = IDEEncoding.getIDEEncodings(); String resourcePreference = getStoredValue(); populateEncodingsCombo(encodings, resourcePreference); updateEncodingState(resourcePreference == null); } } /** * Returns the value that is currently stored for the encoding. * * @return the currently stored encoding */ protected abstract String getStoredValue(); /* * (non-Javadoc) * * @see org.eclipse.jface.preference.FieldEditor#doLoadDefault() */ protected void doLoadDefault() { updateEncodingState(true); } /* * (non-Javadoc) * * @see org.eclipse.jface.preference.FieldEditor#getNumberOfControls() */ public int getNumberOfControls() { return 1; } /* * (non-Javadoc) * * @see org.eclipse.jface.preference.FieldEditor#isValid() */ public boolean isValid() { return isValid; } /* * (non-Javadoc) * * @see org.eclipse.jface.preference.FieldEditor#refreshValidState() */ protected void refreshValidState() { updateValidState(); } /* * (non-Javadoc) * * @see org.eclipse.jface.preference.FieldEditor#setPreferenceStore(org.eclipse.jface.preference.IPreferenceStore) */ public void setPreferenceStore(IPreferenceStore store) { super.setPreferenceStore(store); defaultEnc = store.getDefaultString(getPreferenceName()); updateDefaultEncoding(); } private void updateDefaultEncoding() { defaultEncodingButton.setText(defaultButtonText()); } private Composite getContainer() { return container; } /** * Creates a composite with all the encoding controls. * <p> * Subclasses may extend. * </p> * * @param parent * the parent widget * @param numColumns * the number of columns in the parent * @return the group control */ protected Composite createEncodingGroup(Composite parent, int numColumns) { Composite topControl; GridLayout layout = new GridLayout(); layout.numColumns = 2; if (groupTitle == null) { topControl = new Composite(parent, SWT.NONE); layout.marginWidth = 0; layout.marginHeight = 0; } else { Group top = new Group(parent, SWT.NONE); top.setText(groupTitle); topControl = top; } GridData data = new GridData(GridData.FILL_HORIZONTAL); topControl.setLayoutData(data); topControl.setLayout(layout); SelectionAdapter buttonListener = new SelectionAdapter() { public void widgetSelected(SelectionEvent e) { updateEncodingState(defaultEncodingButton.getSelection()); updateValidState(); } }; defaultEncodingButton = new Button(topControl, SWT.RADIO); defaultEnc = findDefaultEncoding(); defaultEncodingButton.setText(defaultButtonText()); data = new GridData(); data.horizontalSpan = 2; defaultEncodingButton.setLayoutData(data); defaultEncodingButton.addSelectionListener(buttonListener); otherEncodingButton = new Button(topControl, SWT.RADIO); otherEncodingButton.setText(IDEWorkbenchMessages.WorkbenchPreference_otherEncoding); otherEncodingButton.addSelectionListener(buttonListener); encodingCombo = new Combo(topControl, SWT.NONE); data = new GridData(); encodingCombo.setLayoutData(data); encodingCombo.addSelectionListener(new SelectionAdapter() { /* * (non-Javadoc) * * @see org.eclipse.swt.events.SelectionListener#widgetSelected(org.eclipse.swt.events.SelectionEvent) */ public void widgetSelected(SelectionEvent e) { updateValidState(); } }); encodingCombo.addKeyListener(new KeyAdapter() { /* * (non-Javadoc) * * @see org.eclipse.swt.events.KeyListener#keyReleased(org.eclipse.swt.events.KeyEvent) */ public void keyReleased(KeyEvent e) { updateValidState(); } }); return topControl; } /* * (non-Javadoc) * * @see org.eclipse.jface.preference.FieldEditor#setEnabled(boolean, * org.eclipse.swt.widgets.Composite) * @since 3.3 */ public void setEnabled(boolean enabled, Composite parent) { if (container != null) container.setEnabled(enabled); if (defaultEncodingButton != null) defaultEncodingButton.setEnabled(enabled); if (otherEncodingButton != null) otherEncodingButton.setEnabled(enabled); if (encodingCombo != null) encodingCombo.setEnabled(enabled && otherEncodingButton.getSelection()); } /** * Returns the default encoding for the object being shown. * * @return the default encoding for the object being shown */ protected String findDefaultEncoding() { return WorkbenchEncoding.getWorkbenchDefaultEncoding(); } /** * Returns the text for the default encoding button. * * @return the text for the default encoding button */ protected String defaultButtonText() { return NLS.bind(IDEWorkbenchMessages.WorkbenchPreference_defaultEncoding, defaultEnc); } /** * Populates the encodings combo. Sets the text based on the selected * encoding. If there is no selected encoding, the text is set to the * default encoding. * * @param encodings * the list of encodings (list of String) * @param selectedEncoding * the selected encoding, or <code>null</code> */ private void populateEncodingsCombo(List encodings, String selectedEncoding) { String[] encodingStrings = new String[encodings.size()]; encodings.toArray(encodingStrings); encodingCombo.setItems(encodingStrings); if (selectedEncoding == null) { encodingCombo.setText(getDefaultEnc()); } else { encodingCombo.setText(selectedEncoding); } } private void updateEncodingState(boolean useDefault) { defaultEncodingButton.setSelection(useDefault); otherEncodingButton.setSelection(!useDefault); if (useDefault) { encodingCombo.setText(getDefaultEnc()); } encodingCombo.setEnabled(!useDefault); setPresentsDefaultValue(useDefault); updateValidState(); } private void updateValidState() { boolean isValidNow = isEncodingValid(); if (isValidNow != isValid) { isValid = isValidNow; if (isValid) { clearErrorMessage(); } else { showErrorMessage(IDEWorkbenchMessages.WorkbenchPreference_unsupportedEncoding); } fireStateChanged(IS_VALID, !isValid, isValid); } String newValue = getSelectedEncoding(); if (isValid && !newValue.equals(oldSelectedEncoding)) { fireValueChanged(VALUE, oldSelectedEncoding, newValue); oldSelectedEncoding = newValue; } } /** * Returns the currently selected encoding. * * @return the currently selected encoding */ protected String getSelectedEncoding() { if (defaultEncodingButton.getSelection()) { return defaultEnc; } return encodingCombo.getText(); } private boolean isEncodingValid() { return defaultEncodingButton.getSelection() || isValidEncoding(encodingCombo.getText()); } /** * Returns whether or not the given encoding is valid. * * @param enc * the encoding to validate * @return <code>true</code> if the encoding is valid, <code>false</code> * otherwise */ private boolean isValidEncoding(String enc) { try { return Charset.isSupported(enc); } catch (IllegalCharsetNameException e) { // This is a valid exception return false; } } /** * Returns the default encoding. * * @return the default encoding */ protected String getDefaultEnc() { return defaultEnc; } /** * Returns whether or not the encoding setting changed. * * @param encodingSetting * the setting from the page. * @return boolean <code>true</code> if the resource encoding is the same * as before. */ protected boolean hasSameEncoding(String encodingSetting) { String current = getStoredValue(); if (encodingSetting == null) { // Changed if default is selected and there is no setting return current == null || current.length() == 0; } return encodingSetting.equals(current); } /** * Return whether or not the default has been selected. * * @return <code>true</code> if the default button has been selected. */ boolean isDefaultSelected() { return defaultEncodingButton.getSelection(); } /** * Set the title of the group to groupTitle. If this is not called a default * title is used. If groupTitle is <code>null</code> the control will be * unlabelled (by default a {@link Composite} instead of a {@link Group}. * * <strong>NOTE</strong> this value must be set before * {@link #createControl(Composite)} is called or it will be ignored. * * @param groupTitle * The groupTitle to set. * @since 3.3 */ public void setGroupTitle(String groupTitle) { this.groupTitle = groupTitle; } }