jlistadapterprovider.java

java属性邦定的（JSR-295）的一个实现

/*
 * Copyright (C) 2006-2007 Sun Microsystems, Inc. All rights reserved. Use is
 * subject to license terms.
 */

package org.jdesktop.swingbinding.adapters;

import java.beans.*;
import javax.swing.*;
import org.jdesktop.beansbinding.ext.BeanAdapterProvider;
import org.jdesktop.swingbinding.impl.ListBindingManager;
import javax.swing.event.*;
import java.util.List;
import java.util.ArrayList;

/**
 * @author Shannon Hickey
 */
public final class JListAdapterProvider implements BeanAdapterProvider {

    private static final String SELECTED_ELEMENT_P = "selectedElement";
    private static final String SELECTED_ELEMENTS_P = "selectedElements";
    private static final String SELECTED_ELEMENT_IA_P = SELECTED_ELEMENT_P + "_IGNORE_ADJUSTING";
    private static final String SELECTED_ELEMENTS_IA_P = SELECTED_ELEMENTS_P + "_IGNORE_ADJUSTING";

    public final class Adapter extends BeanAdapterBase {
        private JList list;
        private Handler handler;
        private Object cachedElementOrElements;

        private Adapter(JList list, String property) {
            super(property);
            this.list = list;
        }

        private boolean isPlural() {
            return property == SELECTED_ELEMENTS_P || property == SELECTED_ELEMENTS_IA_P;
        }

        public Object getSelectedElement() {
            return JListAdapterProvider.getSelectedElement(list);
        }
        
        public Object getSelectedElement_IGNORE_ADJUSTING() {
            return getSelectedElement();
        }

        public List<Object> getSelectedElements() {
            return JListAdapterProvider.getSelectedElements(list);
        }

        public List<Object> getSelectedElements_IGNORE_ADJUSTING() {
            return getSelectedElements();
        }
        
        protected void listeningStarted() {
            handler = new Handler();
            cachedElementOrElements = isPlural() ?
                getSelectedElements() : getSelectedElement();
            list.addPropertyChangeListener("model", handler);
            list.addPropertyChangeListener("selectionModel", handler);
            list.getSelectionModel().addListSelectionListener(handler);
        }
        
        protected void listeningStopped() {
            list.getSelectionModel().removeListSelectionListener(handler);
            list.removePropertyChangeListener("model", handler);
            list.removePropertyChangeListener("selectionModel", handler);
            cachedElementOrElements = null;
            handler = null;
        }

        private class Handler implements ListSelectionListener, PropertyChangeListener {
            private void listSelectionChanged() {
                Object oldElementOrElements = cachedElementOrElements;
                cachedElementOrElements = isPlural() ?
                    getSelectedElements() : getSelectedElement();
                firePropertyChange(oldElementOrElements, cachedElementOrElements);
            }

            public void valueChanged(ListSelectionEvent e) {
                if ((property == SELECTED_ELEMENT_IA_P || property == SELECTED_ELEMENTS_IA_P)
                        && e.getValueIsAdjusting()) {

                    return;
                }

                listSelectionChanged();
            }
            
            public void propertyChange(PropertyChangeEvent pce) {
                String propertyName = pce.getPropertyName();

                if (propertyName == "selectionModel") {
                    ((ListSelectionModel)pce.getOldValue()).removeListSelectionListener(handler);
                    ((ListSelectionModel)pce.getNewValue()).addListSelectionListener(handler);
                    listSelectionChanged();
                } else if (propertyName == "model") {
                    listSelectionChanged();
                }
            }
        }
    }

    private static List<Object> getSelectedElements(JList list) {
        assert list != null;

        ListSelectionModel selectionModel = list.getSelectionModel();
        int min = selectionModel.getMinSelectionIndex();
        int max = selectionModel.getMaxSelectionIndex();

        List<Object> newSelection;

        if (min < 0 || max < 0) {
            return new ArrayList<Object>(0);
        }
        
        ArrayList<Object> elements = new ArrayList<Object>(max - min + 1);

        for (int i = min; i <= max; i++) {
            if (selectionModel.isSelectedIndex(i)) {
                elements.add(getElement(list, i));
            }
        }

        return elements;
    }
    
    private static Object getSelectedElement(JList list) {
        assert list != null;

        // PENDING(shannonh) - more cases to consider
        int index = list.getSelectionModel().getLeadSelectionIndex();
        index = list.getSelectionModel().isSelectedIndex(index) ?
            index : list.getSelectionModel().getMinSelectionIndex();

        if (index == -1) {
            return null;
        }

        return getElement(list, index);
    }

    private static Object getElement(JList list, int index) {
        ListModel model = list.getModel();
        return model instanceof ListBindingManager ? ((ListBindingManager)model).getElement(index)
                                                   : model.getElementAt(index);
    }
    
    public boolean providesAdapter(Class<?> type, String property) {
        if (!JList.class.isAssignableFrom(type)) {
            return false;
        }

        property = property.intern();

        return property == SELECTED_ELEMENT_P ||
               property == SELECTED_ELEMENT_IA_P ||
               property == SELECTED_ELEMENTS_P ||
               property == SELECTED_ELEMENTS_IA_P;
                 
    }
    
    public Object createAdapter(Object source, String property) {
        if (!providesAdapter(source.getClass(), property)) {
            throw new IllegalArgumentException();
        }
        
        return new Adapter((JList)source, property);
    }
    
    public Class<?> getAdapterClass(Class<?> type) {
        return JList.class.isAssignableFrom(type) ? 
            JListAdapterProvider.Adapter.class :
            null;
    }
    
}