resourcemanager.java

eclipse开发笔记

package com.swtdesigner;
import java.io.File;
import java.io.InputStream;
import java.lang.reflect.Constructor;
import java.lang.reflect.Method;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.HashMap;
import java.util.Iterator;
import org.eclipse.jface.resource.ImageDescriptor;
import org.eclipse.swt.graphics.*;

/**
 * Utility class for managing OS resources associated with SWT/JFace controls such as
 * colors, fonts, images, etc.
 * 
 * !!! IMPORTANT !!! Application code must explicitly invoke the <code>dispose()</code>
 * method to release the operating system resources managed by cached objects
 * when those objects and OS resources are no longer needed (e.g. on
 * application shutdown)
 * 
 * This class may be freely distributed as part of any application or plugin.
 * <p>
 * Copyright (c) 2003 - 2005, Instantiations, Inc. <br>All Rights Reserved
 * 
 * @author scheglov_ke
 * @author Dan Rubel
 */
public class ResourceManager extends SWTResourceManager {

    /**
     * Dispose of cached objects and their underlying OS resources. This should
     * only be called when the cached objects are no longer needed (e.g. on
     * application shutdown)
     */
    public static void dispose() {
        disposeColors();
        disposeFonts();
        disposeImages();
        disposeCursors();
    }

    //////////////////////////////
    // Image support
    //////////////////////////////

	/**
	 * Maps image descriptors to images
	 */
    private static HashMap<ImageDescriptor, Image> m_DescriptorImageMap = new HashMap<ImageDescriptor, Image>();
    
    /**
     * Returns an image descriptor stored in the file at the specified path relative to the specified class
     * @param clazz Class The class relative to which to find the image descriptor
     * @param path String The path to the image file
     * @return ImageDescriptor The image descriptor stored in the file at the specified path
     */
    public static ImageDescriptor getImageDescriptor(Class clazz, String path) {
        return ImageDescriptor.createFromFile(clazz, path);
    }

    /**
     * Returns an image descriptor stored in the file at the specified path
     * @param path String The path to the image file
     * @return ImageDescriptor The image descriptor stored in the file at the specified path
     */
    public static ImageDescriptor getImageDescriptor(String path) {
        try {
            return ImageDescriptor.createFromURL((new File(path)).toURL());
        } catch (MalformedURLException e) {
            return null;
        }
    }

    /**
     * Returns an image based on the specified image descriptor
     * @param descriptor ImageDescriptor The image descriptor for the image
     * @return Image The image based on the specified image descriptor
     */
    public static Image getImage(ImageDescriptor descriptor) {
        if (descriptor == null)
            return null;
        Image image = m_DescriptorImageMap.get(descriptor);
        if (image == null) {
            image = descriptor.createImage();
            m_DescriptorImageMap.put(descriptor, image);
        }
        return image;
    }

    /**
     * Dispose all of the cached images
     */
    public static void disposeImages() {
    	SWTResourceManager.disposeImages();
    	//
        for (Iterator I = m_DescriptorImageMap.values().iterator(); I.hasNext();)
             ((Image) I.next()).dispose();
        m_DescriptorImageMap.clear();
    }

    //////////////////////////////
    // Plugin images support
    //////////////////////////////

    /**
     * Maps URL to images
     */
    private static HashMap<URL, Image> m_URLImageMap = new HashMap<URL, Image>();

    /**
     * Retuns an image based on a plugin and file path
     * @param plugin Object The plugin containing the image
     * @param name String The path to th eimage within the plugin
     * @return Image The image stored in the file at the specified path
     */
    public static Image getPluginImage(Object plugin, String name) {
        try {
            try {
                URL url = getPluginImageURL(plugin, name);
                if (m_URLImageMap.containsKey(url))
                    return m_URLImageMap.get(url);
                InputStream is = url.openStream();
                Image image;
                try {
                    image = getImage(is);
                    m_URLImageMap.put(url, image);
                } finally {
                    is.close();
                }
                return image;
            } catch (Throwable e) {
            	// Ignore any exceptions
            }
        } catch (Throwable e) {
        	// Ignore any exceptions
        }
        return null;
    }

    /**
     * Retuns an image descriptor based on a plugin and file path
     * @param plugin Object The plugin containing the image
     * @param name String The path to th eimage within the plugin
     * @return ImageDescriptor The image descriptor stored in the file at the specified path
     */
    public static ImageDescriptor getPluginImageDescriptor(Object plugin, String name) {
        try {
            try {
                URL url = getPluginImageURL(plugin, name);
                return ImageDescriptor.createFromURL(url);
            } catch (Throwable e) {
            	// Ignore any exceptions
            }
        } catch (Throwable e) {
        	// Ignore any exceptions
        }
        return null;
    }

    /**
     * Retuns an URL based on a plugin and file path
     * @param plugin Object The plugin containing the file path
     * @param name String The file path
     * @return URL The URL representing the file at the specified path
     * @throws Exception
     */
	@SuppressWarnings("unchecked") //$NON-NLS-1$
	private static URL getPluginImageURL(Object plugin, String name) throws Exception {
		// try to work with 'plugin' as with OSGI BundleContext
		try {
			Class bundleClass = Class.forName("org.osgi.framework.Bundle"); //$NON-NLS-1$
			Class bundleContextClass = Class.forName("org.osgi.framework.BundleContext"); //$NON-NLS-1$
			if (bundleContextClass.isAssignableFrom(plugin.getClass())) {
				Method getBundleMethod = bundleContextClass.getMethod("getBundle", new Class[]{}); //$NON-NLS-1$
				Object bundle = getBundleMethod.invoke(plugin, new Object[]{});
				//
				Class ipathClass = Class.forName("org.eclipse.core.runtime.IPath"); //$NON-NLS-1$
				Class pathClass = Class.forName("org.eclipse.core.runtime.Path"); //$NON-NLS-1$
				Constructor pathConstructor = pathClass.getConstructor(new Class[]{String.class});
				Object path = pathConstructor.newInstance(new Object[]{name});
				//
				Class platformClass = Class.forName("org.eclipse.core.runtime.Platform"); //$NON-NLS-1$
				Method findMethod = platformClass.getMethod("find", new Class[]{bundleClass, ipathClass}); //$NON-NLS-1$
				return (URL) findMethod.invoke(null, new Object[]{bundle, path});
			}
		} catch (Throwable e) {
        	// Ignore any exceptions
		}
		// else work with 'plugin' as with usual Eclipse plugin
		{
			Class pluginClass = Class.forName("org.eclipse.core.runtime.Plugin"); //$NON-NLS-1$
			if (pluginClass.isAssignableFrom(plugin.getClass())) {
				//
				Class ipathClass = Class.forName("org.eclipse.core.runtime.IPath"); //$NON-NLS-1$
				Class pathClass = Class.forName("org.eclipse.core.runtime.Path"); //$NON-NLS-1$
				Constructor pathConstructor = pathClass.getConstructor(new Class[]{String.class});
				Object path = pathConstructor.newInstance(new Object[]{name});
				//
				Method findMethod = pluginClass.getMethod("find", new Class[]{ipathClass}); //$NON-NLS-1$
				return (URL) findMethod.invoke(plugin, new Object[]{path});
			}
		}
		return null;
	}
}