NIO客户端和服务端的一些例子
转自https://www.oschina.net/question/54100_33531
客户端
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"); } } 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(); } } }
服务端
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(); } } } } 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; } 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 } }
服务端 例子2
package com.stevex.app.nio; import java.io.IOException; import java.net.InetSocketAddress; import java.nio.ByteBuffer; import java.nio.CharBuffer; import java.nio.channels.ClosedChannelException; import java.nio.channels.SelectionKey; import java.nio.channels.Selector; import java.nio.channels.ServerSocketChannel; import java.nio.channels.SocketChannel; import java.util.Iterator; public class XiaoNa { private ByteBuffer readBuffer; private Selector selector; public static void main(String[] args){ XiaoNa xiaona = new XiaoNa(); xiaona.init(); xiaona.listen(); } private void init(){ readBuffer = ByteBuffer.allocate(1024); ServerSocketChannel servSocketChannel; try { servSocketChannel = ServerSocketChannel.open(); servSocketChannel.configureBlocking(false); //绑定端口 servSocketChannel.socket().bind(new InetSocketAddress(8383)); selector = Selector.open(); servSocketChannel.register(selector, SelectionKey.OP_ACCEPT); } catch (IOException e) { e.printStackTrace(); } } private void listen() { while(true){ try{ selector.select(); Iterator ite = selector.selectedKeys().iterator(); while(ite.hasNext()){ SelectionKey key = (SelectionKey) ite.next(); ite.remove();//确保不重复处理 handleKey(key); } } catch(Throwable t){ t.printStackTrace(); } } } private void handleKey(SelectionKey key) throws IOException, ClosedChannelException { SocketChannel channel = null; try{ if(key.isAcceptable()){ ServerSocketChannel serverChannel = (ServerSocketChannel) key.channel(); channel = serverChannel.accept();//接受连接请求 channel.configureBlocking(false); channel.register(selector, SelectionKey.OP_READ); } else if(key.isReadable()){ channel = (SocketChannel) key.channel(); readBuffer.clear(); /*当客户端channel关闭后，会不断收到read事件，但没有消息，即read方法返回-1 * 所以这时服务器端也需要关闭channel，避免无限无效的处理*/ int count = channel.read(readBuffer); if(count > 0){ //一定需要调用flip函数，否则读取错误数据 readBuffer.flip(); /*使用CharBuffer配合取出正确的数据 String question = new String(readBuffer.array()); 可能会出错，因为前面readBuffer.clear();并未真正清理数据 只是重置缓冲区的position, limit, mark， 而readBuffer.array()会返回整个缓冲区的内容。 decode方法只取readBuffer的position到limit数据。 例如，上一次读取到缓冲区的是"where", clear后position为0，limit为 1024， 再次读取“bye"到缓冲区后，position为3，limit不变， flip后position为0，limit为3，前三个字符被覆盖了，但"re"还存在缓冲区中， 所以 new String(readBuffer.array()) 返回 "byere", 而decode(readBuffer)返回"bye"。 */ CharBuffer charBuffer = CharsetHelper.decode(readBuffer); String question = charBuffer.toString(); String answer = getAnswer(question); channel.write(CharsetHelper.encode(CharBuffer.wrap(answer))); } else{ //这里关闭channel，因为客户端已经关闭channel或者异常了 channel.close(); } } } catch(Throwable t){ t.printStackTrace(); if(channel != null){ channel.close(); } } } private String getAnswer(String question){ String answer = null; switch(question){ case "who": answer = "我是小娜\n"; break; case "what": answer = "我是来帮你解闷的\n"; break; case "where": answer = "我来自外太空\n"; break; case "hi": answer = "hello\n"; break; case "bye": answer = "88\n"; break; default: answer = "请输入 who， 或者what， 或者where"; } return answer; } }
