Java NIO實現群聊系統
本文實例為大傢分享瞭Java NIO實現群聊系統的具體代碼,供大傢參考,具體內容如下
前面的文章介紹瞭NIO的三大核心組件並編寫瞭BIO的一個demo實例,本文使用NIO寫一個小應用實例,鞏固並加深對NIO的理解。
實例要求:
1)編寫一個 NIO 群聊系統,實現服務器端和客戶端之間的數據簡單通訊(非阻塞)
2)實現多人群聊
3)服務器端:可以監測用戶上線,離線,並實現消息轉發功能
4)客戶端:通過channel 可以無阻塞發送消息給其它所有用戶,同時可以接受其它用戶發送的消息(有服務器轉發得到)
5)目的:進一步理解NIO非阻塞網絡編程機制
服務端代碼:
import java.io.IOException; import java.net.InetSocketAddress; import java.nio.ByteBuffer; import java.nio.channels.*; import java.util.Iterator; public class GroupChatServer { //定義屬性 private Selector selector; private ServerSocketChannel listenChannel; private static final int PORT = 6667; //構造器 //初始化工作 public GroupChatServer() { try { //得到選擇器 selector = Selector.open(); //ServerSocketChannel listenChannel = ServerSocketChannel.open(); //綁定端口 listenChannel.socket().bind(new InetSocketAddress(PORT)); //設置非阻塞模式 listenChannel.configureBlocking(false); //將該listenChannel 註冊到selector listenChannel.register(selector, SelectionKey.OP_ACCEPT); }catch (IOException e) { e.printStackTrace(); } } //監聽 public void listen() { System.out.println("監聽線程: " + Thread.currentThread().getName()); try { //循環處理 while (true) { int count = selector.select(); if(count > 0) {//有事件處理 //遍歷得到selectionKey 集合 Iterator<SelectionKey> iterator = selector.selectedKeys().iterator(); while (iterator.hasNext()) { //取出selectionkey SelectionKey key = iterator.next(); //監聽到accept if(key.isAcceptable()) { SocketChannel sc = listenChannel.accept(); sc.configureBlocking(false); //將該 sc 註冊到seletor sc.register(selector, SelectionKey.OP_READ); //提示 System.out.println(sc.getRemoteAddress() + " 上線 "); } if(key.isReadable()) { //通道發送read事件,即通道是可讀的狀態 //處理讀 (專門寫方法..) readData(key); } //當前的key 刪除,防止重復處理 iterator.remove(); } } else { System.out.println("等待...."); } } }catch (Exception e) { e.printStackTrace(); }finally { //發生異常處理.... } } //讀取客戶端消息 private void readData(SelectionKey key) { //取到關聯的channle SocketChannel channel = null; try { //得到channel channel = (SocketChannel) key.channel(); //創建buffer ByteBuffer buffer = ByteBuffer.allocate(1024); int count = channel.read(buffer); //根據count的值做處理 if(count > 0) { //把緩存區的數據轉成字符串 String msg = new String(buffer.array()); //輸出該消息 System.out.println("form 客戶端: " + msg); //向其它的客戶端轉發消息(去掉自己), 專門寫一個方法來處理 sendInfoToOtherClients(msg, channel); } }catch (IOException e) { try { System.out.println(channel.getRemoteAddress() + " 離線瞭.."); //取消註冊 key.cancel(); //關閉通道 channel.close(); }catch (IOException e2) { e2.printStackTrace();; } } } //轉發消息給其它客戶(通道) private void sendInfoToOtherClients(String msg, SocketChannel self ) throws IOException{ System.out.println("服務器轉發消息中..."); System.out.println("服務器轉發數據給客戶端線程: " + Thread.currentThread().getName()); //遍歷 所有註冊到selector 上的 SocketChannel,並排除 self for(SelectionKey key: selector.keys()) { //通過 key 取出對應的 SocketChannel Channel targetChannel = key.channel(); //排除自己 if(targetChannel instanceof SocketChannel && targetChannel != self) { //轉型 SocketChannel dest = (SocketChannel)targetChannel; //將msg 存儲到buffer ByteBuffer buffer = ByteBuffer.wrap(msg.getBytes()); //將buffer 的數據寫入 通道 dest.write(buffer); } } } public static void main(String[] args) { //創建服務器對象 GroupChatServer groupChatServer = new GroupChatServer(); groupChatServer.listen(); } } //可以寫一個Handler class MyHandler { public void readData() { } public void sendInfoToOtherClients(){ } }
客戶端代碼:
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 { //定義相關的屬性 private final String HOST = "127.0.0.1"; // 服務器的ip private final int PORT = 6667; //服務器端口 private Selector selector; private SocketChannel socketChannel; private String username; //構造器, 完成初始化工作 public GroupChatClient() throws IOException { selector = Selector.open(); //連接服務器 socketChannel = socketChannel.open(new InetSocketAddress("127.0.0.1", PORT)); //設置非阻塞 socketChannel.configureBlocking(false); //將channel 註冊到selector socketChannel.register(selector, SelectionKey.OP_READ); //得到username username = socketChannel.getLocalAddress().toString().substring(1); System.out.println(username + " is ok..."); } //向服務器發送消息 public void sendInfo(String info) { info = username + " 說:" + info; try { socketChannel.write(ByteBuffer.wrap(info.getBytes())); }catch (IOException e) { e.printStackTrace(); } } //讀取從服務器端回復的消息 public void readInfo() { try { int readChannels = selector.select(); if(readChannels > 0) {//有可以用的通道 Iterator<SelectionKey> iterator = selector.selectedKeys().iterator(); while (iterator.hasNext()) { SelectionKey key = iterator.next(); if(key.isReadable()) { //得到相關的通道 SocketChannel sc = (SocketChannel) key.channel(); //得到一個Buffer ByteBuffer buffer = ByteBuffer.allocate(1024); //讀取 sc.read(buffer); //把讀到的緩沖區的數據轉成字符串 String msg = new String(buffer.array()); System.out.println(msg.trim()); } } iterator.remove(); //刪除當前的selectionKey, 防止重復操作 } else { //System.out.println("沒有可以用的通道..."); } }catch (Exception e) { e.printStackTrace(); } } public static void main(String[] args) throws Exception { //啟動我們客戶端 GroupChatClient chatClient = new GroupChatClient(); //啟動一個線程, 每隔3秒,讀取從服務器發送數據 new Thread() { public void run() { while (true) { chatClient.readInfo(); try { Thread.currentThread().sleep(3000); }catch (InterruptedException e) { e.printStackTrace(); } } } }.start(); //發送數據給服務器端 Scanner scanner = new Scanner(System.in); while (scanner.hasNextLine()) { String s = scanner.nextLine(); chatClient.sendInfo(s); } } }
註意:必須設置通道為非阻塞,才能向Selector註冊,否則報 java.nio.channels.IllegalBlockingModeException 錯
註意:在客戶端上要想獲取得到服務端的數據,也需要註冊在register上(監聽讀事件)
以上就是本文的全部內容,希望對大傢的學習有所幫助,也希望大傢多多支持WalkonNet。