SystemUtils.java

package com.pivotalservices.java2r;

import java.io.File;
import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.net.URL;
import java.net.URLClassLoader;
import java.util.Arrays;

public abstract class SystemUtils {

	private SystemUtils() {
	}

	public static void addToClassPath(File file) {
		if (!file.exists()) {
			throw new RuntimeException(file + " not found");
		}
		try {
			Method method = URLClassLoader.class.getDeclaredMethod("addURL",
					new Class[] { URL.class });
			method.setAccessible(true);
			method.invoke(ClassLoader.getSystemClassLoader(),
					new Object[] { file.toURI().toURL() });
		} catch (Exception e) {
			throw new RuntimeException("Error adding JRI.jar to classpath");
		}
	}

	/**
	 * Adds the specified path to the java library path
	 * 
	 * Based on origin by Fahd Shariff
	 * 
	 * @param pathToAdd
	 *            the path to add
	 */
	public static void addLibraryPath(String pathToAdd) {
		try {
			final Field usrPathsField = ClassLoader.class
					.getDeclaredField("usr_paths");
			usrPathsField.setAccessible(true);

			// get array of paths
			final String[] paths = (String[]) usrPathsField.get(null);

			// check if the path to add is already present
			for (String path : paths) {
				if (path.equals(pathToAdd)) {
					return;
				}
			}

			// add the new path
			final String[] newPaths = Arrays.copyOf(paths, paths.length + 1);
			newPaths[newPaths.length - 1] = pathToAdd;
			usrPathsField.set(null, newPaths);
		} catch (Exception e) {
			throw new RuntimeException("Could not add " + pathToAdd
					+ " to library path");
		}
	}
}