java-ee - 请问这个java.nio的例子哪里错了？

Question

直接上代码。
client端：

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.SocketChannel;

public class JavaTest {

    public static void main(String[] args) throws Exception {
        SocketChannel client = SocketChannel.open();
        client.connect(new InetSocketAddress("127.0.0.1", 30003));
        ByteBuffer buffer = ByteBuffer.allocate(1024);

        BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(System.in));
        String console = null;
        byte[] bytes = new byte[1024];
        while ((console = bufferedReader.readLine()) != null) {
            buffer.clear();
            buffer.put(console.getBytes(), 0, console.getBytes().length);
            int n = client.write(buffer);
            System.out.println("Client write: " + n);
            buffer.flip();
            n = client.read(buffer);
            System.out.println("Client read: " + n);
            buffer.get(bytes, 0, n);
            buffer.flip();
            System.out.println(new String(bytes));
        }
        client.close();
    }

}

server端代码：

import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.SelectionKey;
import java.nio.channels.Selector;
import java.nio.channels.ServerSocketChannel;
import java.nio.channels.SocketChannel;
import java.util.Iterator;
import java.util.Set;

public class Test {

    public static void main(String args[]) throws Exception
    {
        ServerSocketChannel server = ServerSocketChannel.open();
        server.socket().bind(new InetSocketAddress("127.0.0.1", 30003));
        Selector selector = Selector.open();

        server.configureBlocking(false);
        SelectionKey skey = server.register(selector, SelectionKey.OP_ACCEPT);
        ByteBuffer buffer = ByteBuffer.allocate(1024);

        while (true) {
            selector.select();
            Set<SelectionKey> result = selector.selectedKeys();
            Iterator<SelectionKey> resultIterator = result.iterator();
            while (resultIterator.hasNext()) {
                SelectionKey eachone = (SelectionKey)resultIterator.next();

                //if server has an acceptable client
                if (eachone.isAcceptable()) {
                    ServerSocketChannel acceptChannel = (ServerSocketChannel)eachone.channel();
                    //new client
                    SocketChannel client = acceptChannel.accept();
                    client.configureBlocking(false);
                    SelectionKey clientkey = acceptChannel.register(selector, SelectionKey.OP_READ);
                } else if (eachone.isReadable()) {
                    SocketChannel client = (SocketChannel)eachone.channel();
                    //readable client
                    byte[] bytes = new byte[1024];
                    buffer.clear();
                    int n = client.read(buffer);
                    System.out.println("Server read: " + n);
                    buffer.flip();
                    buffer.get(bytes, 0, n);
                    System.out.println(new String(bytes));
                    buffer.flip();
                    n = client.write(buffer);
                    System.out.println("Server write: " + n);
                    client.close();
                }
                resultIterator.remove();
            }
        }
    }
}

client端从System.in读入一行字符，write到server端，再从server端read，将server端发回来的字符串输出到System.out上。
调式时出错了，求问为什么。

Answer 1

Don’t you send the error message?