Java|Java NIO实现群聊系统 JavaNIO实现群聊系统

本文实例为大家分享了Java NIO实现群聊系统的具体代码，供大家参考，具体内容如下
前面的文章介绍了NIO的三大核心组件并编写了BIO的一个demo实例，本文使用NIO写一个小应用实例，巩固并加深对NIO的理解。
实例要求：
1）编写一个 NIO 群聊系统，实现服务器端和客户端之间的数据简单通讯（非阻塞）
2）实现多人群聊
3）服务器端：可以监测用户上线，离线，并实现消息转发功能
4）客户端：通过channel 可以无阻塞发送消息给其它所有用户，同时可以接受其它用户发送的消息(有服务器转发得到)
5）目的：进一步理解NIO非阻塞网络编程机制
服务端代码：

import java.io.IOException; import java.net.InetSocketAddress; import java.nio.ByteBuffer; import java.nio.channels.*; import java.util.Iterator; public class GroupChatServer {//定义属性private Selector selector; private ServerSocketChannel listenChannel; private static final int PORT = 6667; //构造器//初始化工作public GroupChatServer() { try {//得到选择器selector = Selector.open(); //ServerSocketChannellistenChannel =ServerSocketChannel.open(); //绑定端口listenChannel.socket().bind(new InetSocketAddress(PORT)); //设置非阻塞模式listenChannel.configureBlocking(false); //将该listenChannel 注册到selectorlistenChannel.register(selector, SelectionKey.OP_ACCEPT); }catch (IOException e) {e.printStackTrace(); }} //监听public void listen() { System.out.println("监听线程: " + Thread.currentThread().getName()); try { //循环处理while (true) { int count = selector.select(); if(count > 0) {//有事件处理 //遍历得到selectionKey 集合Iterator iterator = selector.selectedKeys().iterator(); while (iterator.hasNext()) {//取出selectionkeySelectionKey key = iterator.next(); //监听到acceptif(key.isAcceptable()) {SocketChannel sc = listenChannel.accept(); sc.configureBlocking(false); //将该 sc 注册到seletorsc.register(selector, SelectionKey.OP_READ); //提示System.out.println(sc.getRemoteAddress() + " 上线 "); }if(key.isReadable()) { //通道发送read事件，即通道是可读的状态//处理读 (专门写方法..)readData(key); }//当前的key 删除，防止重复处理iterator.remove(); } } else {System.out.println("等待...."); }} }catch (Exception e) {e.printStackTrace(); }finally {//发生异常处理....}} //读取客户端消息private void readData(SelectionKey key) { //取到关联的channleSocketChannel channel = null; try {//得到channelchannel = (SocketChannel) key.channel(); //创建bufferByteBuffer buffer = ByteBuffer.allocate(1024); int count = channel.read(buffer); //根据count的值做处理if(count > 0) {//把缓存区的数据转成字符串String msg = new String(buffer.array()); //输出该消息System.out.println("form 客户端: " + msg); //向其它的客户端转发消息(去掉自己), 专门写一个方法来处理sendInfoToOtherClients(msg, channel); } }catch (IOException e) {try {System.out.println(channel.getRemoteAddress() + " 离线了.."); //取消注册key.cancel(); //关闭通道channel.close(); }catch (IOException e2) {e2.printStackTrace(); ; }}} //转发消息给其它客户(通道)private void sendInfoToOtherClients(String msg, SocketChannel self ) throwsIOException{ System.out.println("服务器转发消息中..."); System.out.println("服务器转发数据给客户端线程: " + Thread.currentThread().getName()); //遍历所有注册到selector 上的 SocketChannel,并排除 selffor(SelectionKey key: selector.keys()) { //通过 key取出对应的 SocketChannelChannel targetChannel = key.channel(); //排除自己if(targetChannel instanceofSocketChannel && targetChannel != self) {//转型SocketChannel dest = (SocketChannel)targetChannel; //将msg 存储到bufferByteBuffer buffer = ByteBuffer.wrap(msg.getBytes()); //将buffer 的数据写入通道dest.write(buffer); }}} public static void main(String[] args) {//创建服务器对象GroupChatServer groupChatServer = new GroupChatServer(); groupChatServer.listen(); }} //可以写一个Handlerclass MyHandler {public void readData() {}public void sendInfoToOtherClients(){}}

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; import java.util.Iterator; import java.util.Scanner; import java.util.Set; public class GroupChatClient { //定义相关的属性private final String HOST = "127.0.0.1"; // 服务器的ipprivate final int PORT = 6667; //服务器端口private Selector selector; private SocketChannel socketChannel; private String username; //构造器, 完成初始化工作public GroupChatClient() throws IOException { selector = Selector.open(); //连接服务器socketChannel = socketChannel.open(new InetSocketAddress("127.0.0.1", PORT)); //设置非阻塞socketChannel.configureBlocking(false); //将channel 注册到selectorsocketChannel.register(selector, SelectionKey.OP_READ); //得到usernameusername = socketChannel.getLocalAddress().toString().substring(1); System.out.println(username + " is ok..."); } //向服务器发送消息public void sendInfo(String info) { info = username + " 说：" + info; try {socketChannel.write(ByteBuffer.wrap(info.getBytes())); }catch (IOException e) {e.printStackTrace(); }} //读取从服务器端回复的消息public void readInfo() { try { int readChannels = selector.select(); if(readChannels > 0) {//有可以用的通道 Iterator iterator = selector.selectedKeys().iterator(); while (iterator.hasNext()) { SelectionKey key = iterator.next(); if(key.isReadable()) {//得到相关的通道SocketChannel sc = (SocketChannel) key.channel(); //得到一个BufferByteBuffer buffer = ByteBuffer.allocate(1024); //读取sc.read(buffer); //把读到的缓冲区的数据转成字符串String msg = new String(buffer.array()); System.out.println(msg.trim()); }}iterator.remove(); //删除当前的selectionKey, 防止重复操作} else {//System.out.println("没有可以用的通道..."); } }catch (Exception e) {e.printStackTrace(); }} public static void main(String[] args) throws Exception { //启动我们客户端GroupChatClient chatClient = new GroupChatClient(); //启动一个线程, 每隔3秒，读取从服务器发送数据new Thread() {public void run() { while (true) {chatClient.readInfo(); try {Thread.currentThread().sleep(3000); }catch (InterruptedException e) {e.printStackTrace(); }}}}.start(); //发送数据给服务器端Scanner scanner = new Scanner(System.in); while (scanner.hasNextLine()) {String s = scanner.nextLine(); chatClient.sendInfo(s); }}}

注意：必须设置通道为非阻塞，才能向Selector注册，否则报 java.nio.channels.IllegalBlockingModeException 错
注意：在客户端上要想获取得到服务端的数据，也需要注册在register上(监听读事件)
【Java|Java NIO实现群聊系统】以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持脚本之家。