extensionloader.java

来自「JRemoteControl is a simple Java&#8482 dr」· Java 代码 · 共 113 行

/*
 * JRemCntl - Copyright (C) 2007 Filippo Di Vattimo <[e-mail]>
 * See COPYING
 */

package fildiv.jremcntl.server.core;

import java.util.Hashtable;
import java.util.Map;

import fildiv.jremcntl.common.core.Logger;

public class ExtensionLoader {

	private JRemEnv env;
	
	private ExtensionClassLoader extClsLoader;
	
	// single factory instance
	
	private Map factories;
	
	protected ExtensionLoader() {
		this.env = JRemEnv.getInstance();		
		
		extClsLoader = new ExtensionClassLoader();
		
		factories = new Hashtable();
	}
	
	protected void addRepository(String repo) {
		extClsLoader.addRepository(repo);		
	}
	
	protected JRemExtensionFactory getCachedExtensionFactory(String className) {
		return (JRemExtensionFactory) factories.get(className);
	}
	
	protected void addExtensionFactoryToCache(JRemExtensionFactory factory, String className) {
		factories.put(className, factory);
	}
	
	public JRemExtension getExtension(String className) {
		
		JRemExtensionFactory fact = getCachedExtensionFactory(className);
		if (fact != null)
			return createExtension(fact);
		
		fact = createExtensionFactory(className, fact);
		if (fact == null) {
			if (env.isLogEnabled())
				env.getLogger().info(
						"Unable to create factory with class name: " + className);
			return null;		
		}
		
		return createExtension(fact);
	}

	private JRemExtensionFactory createExtensionFactory(String className, JRemExtensionFactory fact) {
		
		Logger log = env.getLogger();
		
		try {
			Class fc = extClsLoader.loadClass(className);
			fact = (JRemExtensionFactory) fc.newInstance();

			addExtensionFactoryToCache(fact, className);

		} catch (ClassNotFoundException e) {
			log.error(e);
			return null;
		} catch (InstantiationException e) {
			log.error(e);
			return null;
		} catch (IllegalAccessException e) {
			log.error(e);
			return null;
		}
		
		return fact;
	}

	private JRemExtension createExtension(JRemExtensionFactory ef) {		
		
		JRemExtension ext = ef.createExtension(createSafeEnv());
		
		registerExtensionProperties(ext);
		
		return ext;
	}
	
	private void registerExtensionProperties(JRemExtension ext) {
		
		JRemProperty properties[] = ext.getProperties();

		if (properties == null)
			return;
		
		JRemPropertyMapper pm = env.getPropertiesMapper();
		
		for (int index = 0; index < properties.length; ++index) {
			
			JRemProperty p = properties[index];
			pm.registerProperty(ext.getID(), p);			
		}		
	}

	protected Environment createSafeEnv() {
		return new JRemExtensionEnv();		
	}
}