服务端代码：
import java.io.IOException;
import java.net.InetSocketAddress;
import java.net.ServerSocket;
import java.net.Socket;
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.nio.charset.Charset;
import java.util.HashMap;
import java.util.Map;
import java.util.Set;
public class NIOSServer {
private int port = 8888;
//解码buffer
private Charset cs = Charset.forName("utf-8");
/*接受数据缓冲区*/
private static ByteBuffer sBuffer = ByteBuffer.allocate(1024);
/*发送数据缓冲区*/
private static ByteBuffer rBuffer = ByteBuffer.allocate(1024);
/*映射客户端channel */
private Map<String, SocketChannel> clientsMap = new HashMap<String, SocketChannel>();
private static Selector selector;
public NIOSServer(int port) {
this.port = port;
try {
init();
}
catch (Exception e) {
e.printStackTrace();
}
}
private void init() throws IOException {
/*
*启动服务器端，配置为非阻塞，绑定端口，注册accept事件
*ACCEPT事件：当服务端收到客户端连接请求时，触发该事件
*/
ServerSocketChannel serverSocketChannel = ServerSocketChannel.open();
serverSocketChannel.configureBlocking(false);
ServerSocket serverSocket = serverSocketChannel.socket();
serverSocket.bind(new InetSocketAddress(port));
selector = Selector.open();
serverSocketChannel.register(selector, SelectionKey.OP_ACCEPT);
System.out.println("server start on port:" + port);
}
/**
* 服务器端轮询监听，select方法会一直阻塞直到有相关事件发生或超时
*/
private void listen() {
while (true) {
try {
selector.select();//返回值为本次触发的事件数
Set<SelectionKey> selectionKeys = selector.selectedKeys();
for (SelectionKey key : selectionKeys) {
handle(key);
}
selectionKeys.clear();//清除处理过的事件
}
catch (Exception e) {
e.printStackTrace();
break;
}
}
}
/**
* 处理不同的事件
*/
private void handle(SelectionKey selectionKey) throws IOException {
ServerSocketChannel server = null;
SocketChannel client = null;
String receiveText = null;
int count = 0;
if (selectionKey.isAcceptable()) {
/*
* 客户端请求连接事件
* serversocket为该客户端建立socket连接，将此socket注册READ事件，监听客户端输入
* READ事件：当客户端发来数据，并已被服务器控制线程正确读取时，触发该事件
*/
server = (ServerSocketChannel)selectionKey.channel();
client = server.accept();
client.configureBlocking(false);
client.register(selector, SelectionKey.OP_READ);
}
else if (selectionKey.isReadable()) {
/*
* READ事件，收到客户端发送数据，读取数据后继续注册监听客户端
*/
client = (SocketChannel)selectionKey.channel();
rBuffer.clear();
count = client.read(rBuffer);
if (count > 0) {
rBuffer.flip();
receiveText = String.valueOf(cs.decode(rBuffer).array());
System.out.println(client.toString() + ":" + receiveText);
dispatch(client, receiveText);
client = (SocketChannel)selectionKey.channel();
//client.register(selector, SelectionKey.OP_READ);
}
}
}
/**
* 把当前客户端信息 推送到其他客户端
*/
private void dispatch(SocketChannel client, String info) throws IOException {
Socket s = client.socket();
String name =
"[" + s.getInetAddress().toString().substring(1) + ":" + Integer.toHexString(client.hashCode()) + "]";
if (!clientsMap.isEmpty()) {
for (Map.Entry<String, SocketChannel> entry : clientsMap.entrySet()) {
SocketChannel temp = entry.getValue();
if (!client.equals(temp)) {
sBuffer.clear();
sBuffer.put((name + ":" + info).getBytes());
sBuffer.flip();
//输出到通道
temp.write(sBuffer);
}
}
}
clientsMap.put(name, client);
}
public static void main(String[] args) throws IOException {
NIOSServer server = new NIOSServer(7777);
server.listen();
}
}
客户端，可运行多个
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;
import java.util.Date;
import java.util.Scanner;
import java.util.Set;
public class NIOSClient {
/*发送数据缓冲区*/
private static ByteBuffer sBuffer = ByteBuffer.allocate(1024);
/*接受数据缓冲区*/
private static ByteBuffer rBuffer = ByteBuffer.allocate(1024);
/*服务器端地址*/
private InetSocketAddress SERVER;
private static Selector selector;
private static SocketChannel client;
private static String receiveText;
private static String sendText;
private static int count = 0;
public NIOSClient(int port) {
SERVER = new InetSocketAddress("localhost", port);
init();
}
public void init() {
try {
/*
* 客户端向服务器端发起建立连接请求
*/
SocketChannel socketChannel = SocketChannel.open();
socketChannel.configureBlocking(false);
selector = Selector.open();
socketChannel.register(selector, SelectionKey.OP_CONNECT);
socketChannel.connect(SERVER);
/*
* 轮询监听客户端上注册事件的发生
*/
while (true) {
selector.select();
Set<SelectionKey> keySet = selector.selectedKeys();
for (final SelectionKey key : keySet) {
handle(key);
}
;
keySet.clear();
}
}
catch (Exception e) {
e.printStackTrace();
}
}
public static void main(String[] args) throws IOException {
new NIOSClient(7777);
}
private void handle(SelectionKey selectionKey) throws IOException {
if (selectionKey.isConnectable()) {
/*
* 连接建立事件，已成功连接至服务器
*/
client = (SocketChannel)selectionKey.channel();
if (client.isConnectionPending()) {
client.finishConnect();
System.out.println("connect success !");
sBuffer.clear();
sBuffer.put((new Date() + " connected!").getBytes());
sBuffer.flip();
client.write(sBuffer);//发送信息至服务器
/* 原文来自站长网
* 启动线程一直监听客户端输入，有信息输入则发往服务器端
* 因为输入流是阻塞的，所以单独线程监听
*/
new Thread() {
@Override
public void run() {
while (true) {
try {
sBuffer.clear();
Scanner cin = new Scanner(System.in);
sendText = cin.nextLine();
System.out.println(sendText);
/*
* 未注册WRITE事件，因为大部分时间channel都是可以写的
*/
sBuffer.put(sendText.getBytes("utf-8"));
sBuffer.flip();
client.write(sBuffer);
}
catch (IOException e) {
e.printStackTrace();
break;
}
}
};
}.start();
}
//注册读事件
client.register(selector, SelectionKey.OP_READ);
}
else if (selectionKey.isReadable()) {
/*
* 读事件触发
* 有从服务器端发送过来的信息，读取输出到屏幕上后，继续注册读事件
* 监听服务器端发送信息
*/
client = (SocketChannel)selectionKey.channel();
rBuffer.clear();
count = client.read(rBuffer);
if (count > 0) {
receiveText = new String(rBuffer.array(), 0, count);
System.out.println(receiveText);
client = (SocketChannel)selectionKey.channel();
client.register(selector, SelectionKey.OP_READ);
}
}
}
}