ClassLoaderUtil.java

/*******************************************************************************
 * Copyright (c) 2010-2012, Mark Czotter, Istvan Rath and Daniel Varro
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 * Mark Czotter - initial API and implementation
 *******************************************************************************/
package org.eclipse.incquery.runtime.util;

import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLClassLoader;
import java.util.ArrayList;
import java.util.List;

import org.eclipse.core.resources.IFile;
import org.eclipse.core.resources.IProject;
import org.eclipse.core.runtime.CoreException;
import org.eclipse.core.runtime.IPath;
import org.eclipse.core.runtime.Path;
import org.eclipse.jdt.core.IJavaProject;
import org.eclipse.jdt.core.JavaCore;
import org.eclipse.jdt.launching.JavaRuntime;

/**
 * 
 * @author Mark Czotter
 * 
 */
public class ClassLoaderUtil {

    /**
     * Returns a {@link ClassLoader} that is capable of loading classes defined in the project of the input file, or in
     * any dependencies of that project.
     * 
     * @param file
     * @return {@link ClassLoader}
     * @throws CoreException
     * @throws MalformedURLException
     */
    public static ClassLoader getClassLoader(IFile file) throws CoreException, MalformedURLException {
        if (file != null) {
            IProject project = file.getProject();
            IJavaProject jp = JavaCore.create(project);
            String[] classPathEntries = JavaRuntime.computeDefaultRuntimeClassPath(jp);
            List<URL> classURLs = getClassesAsURLs(classPathEntries);
            URL[] urls = (URL[]) classURLs.toArray(new URL[classURLs.size()]);
            URLClassLoader loader = URLClassLoader.newInstance(urls, jp.getClass().getClassLoader());
            return loader;
        }
        return null;
    }

    private static List<URL> getClassesAsURLs(String[] classPathEntries) throws MalformedURLException {
        List<URL> urlList = new ArrayList<URL>();
        for (int i = 0; i < classPathEntries.length; i++) {
            String entry = classPathEntries[i];
            IPath path = new Path(entry);
            URL url = path.toFile().toURI().toURL();
            urlList.add(url);
        }
        return urlList;
    }

}