Dynamically modify classpath and library path

Author: Jonathan Feinberg

Diff for: src/jycessing/Runner.java

@@ -17,9 +17,15 @@
 
 import java.io.BufferedReader;
 import java.io.File;
+import java.io.FileFilter;
 import java.io.FileReader;
+import java.io.FilenameFilter;
 import java.io.IOException;
 import java.io.Reader;
+import java.lang.reflect.Field;
+import java.lang.reflect.Method;
+import java.net.URL;
+import java.net.URLClassLoader;
 
 import org.python.core.Py;
 import org.python.core.PyString;
@@ -28,6 +34,8 @@
 import processing.core.PApplet;
 
 public class Runner {
+	static boolean VERBOSE = false;
+
 	private static String read(final Reader r) throws IOException {
 		final BufferedReader reader = new BufferedReader(r);
 		final StringBuilder sb = new StringBuilder(1024);
@@ -42,13 +50,73 @@ private static String read(final Reader r) throws IOException {
 		}
 	}
 
+	// See http://robertmaldon.blogspot.com/2007/11/dynamically-add-to-eclipse-junit.html
+	private static void addJar(final URL url) throws Exception {
+		final URLClassLoader classLoader = (URLClassLoader)ClassLoader.getSystemClassLoader();
+		final Method method = URLClassLoader.class.getDeclaredMethod("addURL", URL.class);
+		method.setAccessible(true);
+		method.invoke(classLoader, new Object[] { url });
+		if (VERBOSE) {
+			System.err.println("Added " + url + " to classpath.");
+		}
+	}
+
+	// See http://forums.sun.com/thread.jspa?threadID=707176
+	private static void addLibraryPath(final String newPath) throws Exception {
+		final Field field = ClassLoader.class.getDeclaredField("usr_paths");
+		field.setAccessible(true);
+		final String[] paths = (String[])field.get(null);
+		for (final String path : paths) {
+			if (newPath.equals(path)) {
+				return;
+			}
+		}
+		final String[] tmp = new String[paths.length + 1];
+		System.arraycopy(paths, 0, tmp, 0, paths.length);
+		tmp[paths.length] = newPath;
+		field.set(null, tmp);
+		if (VERBOSE) {
+			System.err.println("Added " + newPath + " to java.library.path.");
+		}
+	}
+
+	private static void searchForExtraStuff(final File dir) throws Exception {
+		final File[] dlls = dir.listFiles(new FilenameFilter() {
+			public boolean accept(final File dir, final String name) {
+				return name.matches("^.+\\.(so|dll|jnilib)$");
+			}
+		});
+		if (dlls != null && dlls.length > 0) {
+			addLibraryPath(dir.getAbsolutePath());
+		}
+		final File[] jars = dir.listFiles(new FilenameFilter() {
+			public boolean accept(final File dir, final String name) {
+				return name.matches("^.+\\.jar$");
+			}
+		});
+		for (final File jar : jars) {
+			addJar(jar.toURI().toURL());
+		}
+		final File[] dirs = dir.listFiles(new FileFilter() {
+			public boolean accept(final File f) {
+				return f.isDirectory() && f.getName().charAt(0) != '.';
+			}
+		});
+		for (final File d : dirs) {
+			searchForExtraStuff(d);
+		}
+	}
+
 	public static void main(final String[] args) throws Exception {
 		if (args.length < 1) {
 			System.err.println("I need the path of your Python script as an argument.");
 		}
+		if (Boolean.getBoolean("verbose")) {
+			VERBOSE = true;
+		}
 		final String pathname = args[args.length - 1];
 		final String text = read(new FileReader(pathname));
-
+		searchForExtraStuff(new File("libraries"));
 		Py.initPython();
 		final InteractiveConsole interp = new InteractiveConsole();
 		final String path = new File(pathname).getCanonicalFile().getParent();