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/SocketChannel.java

@@ -0,0 +1,78 @@
+package java.nio.channels;
+
+import java.io.IOException;
+import java.net.InetSocketAddress;
+import java.nio.ByteBuffer;
+
+public class SocketChannel extends SelectableChannel
+  implements ReadableByteChannel, WritableByteChannel
+{
+  public static final int InvalidSocket = -1;
+
+  protected int socket = InvalidSocket;
+  protected boolean open = true;
+  protected boolean connected = false;
+
+  public static SocketChannel open() {
+    return new SocketChannel();
+  }
+
+  public void configureBlocking(boolean v) {
+    if (v) throw new IllegalArgumentException();
+  }
+
+  public void connect(InetSocketAddress address) throws Exception {
+    socket = doConnect(address.getHostName(), address.getPort());
+  }
+
+  public void close() throws IOException {
+    super.close();
+    if (! open) return;
+    closeSocket();
+    open = false;
+  }
+
+  public boolean isOpen() {
+    return open;
+  }
+
+  private int doConnect(String host, int port) throws Exception {
+    boolean b[] = new boolean[1];
+    int s = natDoConnect(host, port, b);
+    connected = b[0];
+    return s;
+  }
+
+  public int read(ByteBuffer b) throws IOException {
+    if (b.remaining() == 0) return 0;
+    int r = natRead(socket, b.array(), b.arrayOffset() + b.position(), b.remaining());
+    b.position(b.position() + r);
+    return r;
+  }
+
+  public int write(ByteBuffer b) throws IOException {
+    if (! connected) {
+      natThrowWriteError(socket);
+    }
+    int w = natWrite(socket, b.array(), b.arrayOffset() + b.position(), b.remaining());
+    b.position(b.position() + w);
+    return w;
+  }
+
+  private void closeSocket() {
+    natCloseSocket(socket);
+  }
+
+  int socketFD() {
+    return socket;
+  }
+
+  private static native int natDoConnect(String host, int port, boolean[] connected)
+    throws Exception;
+  private static native int natRead(int socket, byte[] buffer, int offset, int length)
+    throws IOException;
+  private static native int natWrite(int socket, byte[] buffer, int offset, int length)
+    throws IOException;
+  private static native void natThrowWriteError(int socket) throws IOException;
+  private static native void natCloseSocket(int socket);
+}