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/SelectionKey.java

@@ -0,0 +1,68 @@
+package java.nio.channels;
+
+public class SelectionKey {
+  public static final int OP_READ = 1 << 0;
+  public static final int OP_WRITE = 1 << 2;
+  public static final int OP_ACCEPT = 1 << 4;
+//   public static final int OP_CONNECT = 1 << 3;
+
+  private final SelectableChannel channel;
+  private final Selector selector;
+  private int interestOps;
+  private int readyOps;
+  private final Object attachment;
+
+  public SelectionKey(SelectableChannel channel, Selector selector,
+                      int interestOps, Object attachment)
+  {
+    this.channel = channel;
+    this.selector = selector;
+    this.interestOps = interestOps;
+    this.attachment = attachment;
+    this.readyOps = 0;
+  }
+
+  public int interestOps() {
+    return interestOps;
+  }
+
+  public void interestOps(int v) {
+    this.interestOps = v;
+  }
+
+  public int readyOps() {
+    return readyOps;
+  }
+
+  public void readyOps(int v) {
+    this.readyOps = v;
+  }
+
+  public boolean isReadable() {
+    return (readyOps & OP_READ) != 0;
+  }
+
+  public boolean isWritable() {
+    return (readyOps & OP_WRITE) != 0;
+  }
+
+  public boolean isAcceptable() {
+    return (readyOps & OP_ACCEPT) != 0;
+  }
+
+  public boolean isValid() {
+    return channel.isOpen() && selector.isOpen();
+  }
+
+  public SelectableChannel channel() {
+    return channel;
+  }
+
+  public Selector selector() {
+    return selector;
+  }
+
+  public Object attachment() {
+    return attachment;
+  }
+}