Implemented a basic NIO socket channel interface. Non-blocking socket channels

and server socket channels are implemented.  This version works but only when
libnative is linked with g++ (because of C++ object creation code that fails
without this linking)

classpath/java/nio/channels/SelectableChannel.java

@@ -0,0 +1,28 @@
+package java.nio.channels;
+
+import java.io.IOException;
+import java.nio.ByteBuffer;
+
+public abstract class SelectableChannel implements Channel {
+  private SelectionKey key;
+
+  public abstract int read(ByteBuffer b) throws Exception;
+  public abstract int write(ByteBuffer b) throws Exception;
+  public abstract boolean isOpen();
+
+  public SelectionKey register(Selector selector, int interestOps,
+                               Object attachment)
+  {
+    SelectionKey key = new SelectionKey
+      (this, selector, interestOps, attachment);
+    selector.add(key);
+    return key;
+  }
+
+  public void close() throws IOException {
+    if (key != null) {
+      key.selector().remove(key);
+      key = null;
+    }
+  }
+}