flesh out resource URL scheme implementation

classpath/java/lang/SystemClassLoader.java

@@ -1,9 +1,23 @@
 package java.lang;
 
+import java.net.URL;
+import java.net.MalformedURLException;
+
 public class SystemClassLoader extends ClassLoader {
   private Object map;
 
   protected native Class findClass(String name) throws ClassNotFoundException;
 
   protected native Class findLoadedClass(String name);
+
+  private native boolean resourceExists(String name);
+
+  protected URL findResource(String name) {
+    if (resourceExists(name)) {
+      try {
+        return new URL("resource://" + name);
+      } catch (MalformedURLException ignored) { }
+    }
+    return null;
+  }
 }