这只是长征路上的一小步，以后还有待改进。 NIO Selector示意图： 客户端代码：
import java.io.IOException; import java.net.InetSocketAddress; import java.nio.ByteBuffer; import java.nio.channels.SelectionKey; import java.nio.channels.Selector; import java.nio.channels.SocketChannel; /** * NIO TCP 客户端 * * @date 2010-2-3 * @time 下午03:33:26 * @version 1.00 */ public class TCPClient{ // 信道选择器 private Selector selector; // 与服务器通信的信道 SocketChannel socketChannel; // 要连接的服务器Ip地址 private String hostIp; // 要连接的远程服务器在监听的端口 private int hostListenningPort; /** * 构造函数 * @param HostIp * @param HostListenningPort * @throws IOException */ public TCPClient(String HostIp, int HostListenningPort) throws IOException{ this .hostIp = HostIp; this .hostListenningPort = HostListenningPort; initialize(); } /** * 初始化 * @throws IOException */ private void initialize() throws IOException{ // 打开监听信道并设置为非阻塞模式 socketChannel = SocketChannel.open( new InetSocketAddress(hostIp, hostListenningPort)); socketChannel.configureBlocking( false ); // 打开并注册选择器到信道 selector = Selector.open(); socketChannel.register(selector, SelectionKey.OP_READ); // 启动读取线程 new TCPClientReadThread(selector); } /** * 发送字符串到服务器 * @param message * @throws IOException */ public void sendMsg(String message) throws IOException{ ByteBuffer writeBuffer = ByteBuffer.wrap(message.getBytes( " UTF-16 " )); socketChannel.write(writeBuffer); } public static void main(String[] args) throws IOException{ TCPClient client = new TCPClient( " 192.168.0.1 " , 1978 ); client.sendMsg( " 你好!Nio!醉里挑灯看剑,梦回吹角连营 " ); } }客户端读取线程代码：
import java.io.IOException; import java.nio.ByteBuffer; import java.nio.channels.SelectionKey; import java.nio.channels.Selector; import java.nio.channels.SocketChannel; import java.nio.charset.Charset; public class TCPClientReadThread implements Runnable{ private Selector selector; public TCPClientReadThread(Selector selector){ this .selector = selector; new Thread( this ).start(); } public void run() { try { while (selector.select() > 0 ) { // 遍历每个有可用IO操作Channel对应的SelectionKey for (SelectionKey sk : selector.selectedKeys()) { // 如果该SelectionKey对应的Channel中有可读的数据 if (sk.isReadable()) { // 使用NIO读取Channel中的数据 SocketChannel sc = (SocketChannel) sk.channel(); ByteBuffer buffer = ByteBuffer.allocate( 1024 ); sc.read(buffer); buffer.flip(); // 将字节转化为为UTF-16的字符串 String receivedString = Charset.forName( " UTF-16 " ).newDecoder().decode(buffer).toString(); // 控制台打印出来 System.out.println( " 接收到来自服务器 " + sc.socket().getRemoteSocketAddress() + " 的信息: " + receivedString); // 为下一次读取作准备 sk.interestOps(SelectionKey.OP_READ); } // 删除正在处理的SelectionKey selector.selectedKeys().remove(sk); } } } catch (IOException ex) { ex.printStackTrace(); } } }服务器端代码：
import java.io.IOException; import java.net.InetSocketAddress; import java.nio.channels.SelectionKey; import java.nio.channels.Selector; import java.nio.channels.ServerSocketChannel; import java.util.Iterator; /** * TCP服务器端 * * @date 2010-2-3 * @time 上午08:39:48 * @version 1.00 */ public class TCPServer{ // 缓冲区大小 private static final int BufferSize = 1024 ; // 超时时间，单位毫秒 private static final int TimeOut = 3000 ; // 本地监听端口 private static final int ListenPort = 1978 ; public static void main(String[] args) throws IOException{ // 创建选择器 Selector selector = Selector.open(); // 打开监听信道 ServerSocketChannel listenerChannel = ServerSocketChannel.open(); // 与本地端口绑定 listenerChannel.socket().bind( new InetSocketAddress(ListenPort)); // 设置为非阻塞模式 listenerChannel.configureBlocking( false ); // 将选择器绑定到监听信道,只有非阻塞信道才可以注册选择器.并在注册过程中指出该信道可以进行Accept操作 listenerChannel.register(selector, SelectionKey.OP_ACCEPT); // 创建一个处理协议的实现类,由它来具体操作 TCPProtocol protocol = new TCPProtocolImpl(BufferSize); // 反复循环,等待IO while ( true ){ // 等待某信道就绪(或超时) if (selector.select(TimeOut) == 0 ){ System.out.print( " 独自等待. " ); continue ; } // 取得迭代器.selectedKeys()中包含了每个准备好某一I/O操作的信道的SelectionKey Iterator < SelectionKey > keyIter = selector.selectedKeys().iterator(); while (keyIter.hasNext()){ SelectionKey key = keyIter.next(); try { if (key.isAcceptable()){ // 有客户端连接请求时 protocol.handleAccept(key); } if (key.isReadable()){ // 从客户端读取数据 protocol.handleRead(key); } if (key.isValid() && key.isWritable()){ // 客户端可写时 protocol.handleWrite(key); } } catch (IOException ex){ // 出现IO异常（如客户端断开连接）时移除处理过的键 keyIter.remove(); continue ; } // 移除处理过的键 keyIter.remove(); } } } }协议接口代码：
import java.io.IOException; import java.nio.channels.SelectionKey; /** * TCPServerSelector与特定协议间通信的接口 * * @date 2010-2-3 * @time 上午08:42:42 * @version 1.00 */ public interface TCPProtocol{ /** * 接收一个SocketChannel的处理 * @param key * @throws IOException */ void handleAccept(SelectionKey key) throws IOException; /** * 从一个SocketChannel读取信息的处理 * @param key * @throws IOException */ void handleRead(SelectionKey key) throws IOException; /** * 向一个SocketChannel写入信息的处理 * @param key * @throws IOException */ void handleWrite(SelectionKey key) throws IOException; }协议实现类代码：
import java.io.IOException; import java.nio.ByteBuffer; import java.nio.channels.SelectionKey; import java.nio.channels.ServerSocketChannel; import java.nio.channels.SocketChannel; import java.nio.charset.Charset; import java.util.Date; /** * TCPProtocol的实现类 * * @date 2010-2-3 * @time 上午08:58:59 * @version 1.00 */ public class TCPProtocolImpl implements TCPProtocol{ private int bufferSize; public TCPProtocolImpl( int bufferSize){ this .bufferSize = bufferSize; } public void handleAccept(SelectionKey key) throws IOException { SocketChannel clientChannel = ((ServerSocketChannel)key.channel()).accept(); clientChannel.configureBlocking( false ); clientChannel.register(key.selector(), SelectionKey.OP_READ,ByteBuffer.allocate(bufferSize)); } public void handleRead(SelectionKey key) throws IOException { // 获得与客户端通信的信道 SocketChannel clientChannel = (SocketChannel)key.channel(); // 得到并清空缓冲区 ByteBuffer buffer = (ByteBuffer)key.attachment(); buffer.clear(); // 读取信息获得读取的字节数 long bytesRead = clientChannel.read(buffer); if (bytesRead ==- 1 ){ // 没有读取到内容的情况 clientChannel.close(); } else { // 将缓冲区准备为数据传出状态 buffer.flip(); // 将字节转化为为UTF-16的字符串 String receivedString = Charset.forName( " UTF-16 " ).newDecoder().decode(buffer).toString(); // 控制台打印出来 System.out.println( " 接收到来自 " + clientChannel.socket().getRemoteSocketAddress() + " 的信息: " + receivedString); // 准备发送的文本 String sendString = " 你好,客户端. @ " + new Date().toString() + " ，已经收到你的信息 " + receivedString; buffer = ByteBuffer.wrap(sendString.getBytes( " UTF-16 " )); clientChannel.write(buffer); // 设置为下一次读取或是写入做准备 key.interestOps(SelectionKey.OP_READ | SelectionKey.OP_WRITE); } } public void handleWrite(SelectionKey key) throws IOException { // do nothing } }
http://www.blogjava.net/longturi/archive/2010/02/03/311820.html
另外一篇比较好的文章
http://www.oschina.net/question/54100_33530
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