JavaProjectClassLoader.java

package net.sourceforge.pmd.eclipse.runtime.cmd;

import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLClassLoader;
import java.util.HashSet;
import java.util.Set;

import org.apache.log4j.Logger;
import org.eclipse.core.resources.IProject;
import org.eclipse.core.resources.IWorkspaceRoot;
import org.eclipse.core.runtime.CoreException;
import org.eclipse.core.runtime.IPath;
import org.eclipse.jdt.core.IClasspathEntry;
import org.eclipse.jdt.core.IJavaProject;
import org.eclipse.jdt.core.JavaCore;
import org.eclipse.jdt.core.JavaModelException;

/**
 * This is a ClassLoader for the Build Path of an IJavaProject.
 */
public class JavaProjectClassLoader extends URLClassLoader {
	private static final Logger log = Logger.getLogger(JavaProjectClassLoader.class);

	private Set<IJavaProject> javaProjects = new HashSet<IJavaProject>();
	private IWorkspaceRoot workspaceRoot;

	public JavaProjectClassLoader(ClassLoader parent, IProject project) {
		super(new URL[0], parent);
		try {
            if (!project.hasNature(JavaCore.NATURE_ID)) {
                throw new IllegalArgumentException("The project " + project + " is not a java project");
            }
        } catch (CoreException e) {
            throw new IllegalArgumentException("The project " + project + " is not a java project", e);
        }
		workspaceRoot = project.getProject().getWorkspace().getRoot();
		
		IJavaProject javaProject = JavaCore.create(project);
		addURLs(javaProject, false);

		// No longer need these things, drop references
		javaProjects = null;
		workspaceRoot = null;
	}

	private static IProject projectFor(IJavaProject javaProject, IClasspathEntry classpathEntry) {
		return javaProject.getProject().getWorkspace().getRoot().getProject(classpathEntry.getPath().toString());
	}
	
	private void addURLs(IJavaProject javaProject, boolean exportsOnly) {
		
		if (javaProjects.contains(javaProject)) return;
		
		javaProjects.add(javaProject);

		try {
			// Add default output location
			addURL(javaProject.getOutputLocation());

			// Add each classpath entry
			IClasspathEntry[] classpathEntries = javaProject.getResolvedClasspath(true);
			for (IClasspathEntry classpathEntry : classpathEntries) {
				if (classpathEntry.isExported() || !exportsOnly) {
					switch (classpathEntry.getEntryKind()) {

					// Recurse on projects
					case IClasspathEntry.CPE_PROJECT:
						IProject project = projectFor(javaProject, classpathEntry);
						IJavaProject javaProj = JavaCore.create(project);
						if (javaProj != null) {
							addURLs(javaProj, true);
							}
						break;

						// Library
					case IClasspathEntry.CPE_LIBRARY:
						addURL(classpathEntry);
						break;

					// Only Source entries with custom output location need to be added
					case IClasspathEntry.CPE_SOURCE:
						IPath outputLocation = classpathEntry.getOutputLocation();
						if (outputLocation != null) {
							addURL(outputLocation);
							}
						break;

					// Variable and Container entries should not be happening, because we've asked for resolved entries.
					case IClasspathEntry.CPE_VARIABLE:
					case IClasspathEntry.CPE_CONTAINER:
					break;
					}
				}
			}
		} catch (JavaModelException e) {
			log.debug("MalformedURLException occurred: " + e.getLocalizedMessage(), e);
			}
	}

	private void addURL(IClasspathEntry classpathEntry) {
		addURL(classpathEntry.getPath());
	}

	private void addURL(IPath path) {
		try {
			if (workspaceRoot.exists(path)) {
				// path = workspaceRoot.getFileForLocation(path).getFullPath();
				//path = workspaceRoot.getFile(path).getFullPath();
				path = workspaceRoot.getLocation().append(path);
			}
			URL url = path.toFile().getAbsoluteFile().toURI().toURL();
			addURL(url);
		} catch (MalformedURLException e) {
			log.debug("MalformedURLException occurred: " + e.getLocalizedMessage(), e);
		}
	}
}