pluginutility.java

FMJ（freedom media for java)是java视频开发的新选择

package net.sf.fmj.utility;

import java.util.logging.Logger;

import javax.media.Codec;
import javax.media.Demultiplexer;
import javax.media.Effect;
import javax.media.Format;
import javax.media.Multiplexer;
import javax.media.PlugInManager;
import javax.media.Renderer;
import javax.media.protocol.ContentDescriptor;

/**
 * Helper class to register plugins with the PlugInManager, but only requiring the class name.
 * The rest is done by reflection/instantiation/querying.
 * @author Ken Larson
 *
 */
public class PlugInUtility
{
	private static final Logger logger = LoggerSingleton.logger;

	private static final boolean TRACE = false;
	
	public static boolean registerPlugIn(String className)
	{
		
		final Object o;
		try
		{
			final Class clazz = Class.forName(className);
			o = clazz.newInstance();

			if (o instanceof Demultiplexer)
			{
				if (TRACE) logger.fine("PlugInUtility: Registering demultiplexer: " + className);
				final Demultiplexer oCast = (Demultiplexer) o;
				final ContentDescriptor[] contentDescriptors = oCast.getSupportedInputContentDescriptors();
				final Format[] formats = new Format[contentDescriptors.length];
				for (int i = 0; i < contentDescriptors.length; ++i)
				{
					if (TRACE) logger.fine("\t" + contentDescriptors[i]);
					formats[i] = contentDescriptors[i];
				}
				
				return PlugInManager.addPlugIn(className, formats, new Format[] {}, PlugInManager.DEMULTIPLEXER);
				
			}
			else if (o instanceof Codec)
			{
				if (TRACE) logger.fine("PlugInUtility: Registering codec: " + className);
				final Codec oCast = (Codec) o;
				final Format[] inputFormats = oCast.getSupportedInputFormats();
	
				final Format[] outputFormats = oCast.getSupportedOutputFormats(null);	// this is what JMRegistry does
				
				return PlugInManager.addPlugIn(className, inputFormats, outputFormats, (o instanceof Effect) ? PlugInManager.EFFECT : PlugInManager.CODEC);
		
			}
			else if (o instanceof Renderer)
			{
				if (TRACE) logger.fine("PlugInUtility: Registering renderer: " + className);
				final Renderer oCast = (Renderer) o;
				final Format[] inputFormats = oCast.getSupportedInputFormats();
				return PlugInManager.addPlugIn(className, inputFormats, new Format[] {}, PlugInManager.RENDERER);
			}
			else if (o instanceof Multiplexer)
			{	
				if (TRACE) logger.fine("PlugInUtility: Registering Multiplexer: " + className);
				final Multiplexer oCast = (Multiplexer) o;
				// JMF Multiplexers always have nothing for the input formats.
				return PlugInManager.addPlugIn(className, new Format[] {}, oCast.getSupportedOutputContentDescriptors(null), PlugInManager.MULTIPLEXER);
			}
			else
			{
				logger.warning("PlugInUtility: Unknown or unsupported plug-in: " + o.getClass());
				return false;
			}
		
		}
		catch (Throwable e)	// catch Throwable instead of Exception because some plug-ins load native libraries, and if the native libraries are missing, we can get exceptions not caught by Exception
		{
			logger.fine("PlugInUtility: Unable to register plugin " + className + ": " + e);
			return false;
		}
		
	}
}