imagej.patcher.LegacyClassLoader Maven / Gradle / Ivy

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A runtime patcher to introduce extension points into the original ImageJ (1.x). This project offers extension points for use with ImageJ2 and it also offers limited support for headless operations.
There is a newer version: 1.2.7
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/*
 * #%L
 * ImageJ software for multidimensional image processing and analysis.
 * %%
 * Copyright (C) 2009 - 2016 Board of Regents of the University of
 * Wisconsin-Madison, Broad Institute of MIT and Harvard, and Max Planck
 * Institute of Molecular Cell Biology and Genetics.
 * %%
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 * 
 * 1. Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDERS OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 * #L%
 */
package imagej.patcher;

import ij.ImagePlus;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.URL;
import java.net.URLClassLoader;
import java.security.ProtectionDomain;

/**
 * A special purpose class loader to encapsulate ImageJ 1.x "instances" from each other.
 * 
 * @see LegacyEnvironment
 * 
 * @author Johannes Schindelin
 */
@Deprecated
public class LegacyClassLoader extends URLClassLoader {
	private final Class[] knownClasses = new Class[] {
		LegacyHooks.class, LegacyHooks.FatJarNameComparator.class, EssentialLegacyHooks.class, HeadlessGenericDialog.class
	};
	private final int sharedClassCount = 2;

	public LegacyClassLoader(final boolean headless) throws ClassNotFoundException {
		this(headless, new LegacyInjector());
	}

	LegacyClassLoader(final boolean headless, final LegacyInjector injector) throws ClassNotFoundException {
		super(getImageJ1Jar(), determineParent());
		final ClassLoader loader = this;
		injector.injectHooks(loader, headless);
	}

	@Override
	public URL getResource(final String name) {
		if (name.startsWith("imagej/patcher/")) {
			for (final Class clazz : knownClasses) {
				if (name.equals(clazz.getName().replace('.', '/') + ".class")) {
					return clazz.getResource("/" + name);
				}
			}
		}
		return super.getResource(name);
	}

	@Override
	public Class findClass(final String className) throws ClassNotFoundException {
		for (int i = 0; i < knownClasses.length; i++) {
			if (knownClasses[i].getName().equals(className)) try {
				if (i < sharedClassCount) return knownClasses[i];
				final ProtectionDomain domain = knownClasses[i].getProtectionDomain();
				final InputStream in = knownClasses[i].getResourceAsStream("/" + className.replace('.', '/') + ".class");
				final ByteArrayOutputStream out = new ByteArrayOutputStream();
				byte[] buffer = new byte[65536];
				for (;;) {
					int count = in.read(buffer);
					if (count < 0) break;
					out.write(buffer, 0, count);
				}
				in.close();
				buffer = out.toByteArray();
				out.close();
				return defineClass(className, buffer, 0, buffer.length, domain);
			} catch (IOException e) {
				throw new ClassNotFoundException("Could not read bytecode for " + className, e);
			}
		}
		return super.findClass(className);
	}

	private static ClassLoader determineParent() {
		ClassLoader loader = ClassLoader.getSystemClassLoader();
		for (;;) try {
			if (loader.loadClass("ij.IJ") == null) {
				return loader;
			}
			loader = loader.getParent();
			if (loader == null) {
				throw new RuntimeException("Cannot find bootstrap class loader");
			}
		} catch (ClassNotFoundException e) {
			return loader;
		}
	}

	private static URL[] getImageJ1Jar() {
		return new URL[] { Utils.getLocation(ImagePlus.class) };
	}
}