依賴

    <dependencies>
		<dependency>
			<groupId>io.netty</groupId>
			<artifactId>netty-all</artifactId>
			<version>4.1.25.Final</version>
		</dependency>
	</dependencies>

 server

package com.netty.websocket;

import io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.ChannelFuture;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.nio.NioServerSocketChannel;

public class WSServer {

	public static void main(String[] args) throws Exception {
		
		EventLoopGroup mainGroup = new NioEventLoopGroup();
		EventLoopGroup subGroup = new NioEventLoopGroup();
		
		try {
			ServerBootstrap server = new ServerBootstrap();
			server.group(mainGroup, subGroup)
				.channel(NioServerSocketChannel.class)
				.childHandler(new WSServerInitialzer());
			
			ChannelFuture future = server.bind(8088).sync();
			System.out.println("start.....");
			future.channel().closeFuture().sync();
		} finally {
			mainGroup.shutdownGracefully();
			subGroup.shutdownGracefully();
		}
	}
}
 

initializer

package com.netty.websocket;

import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelPipeline;
import io.netty.channel.socket.SocketChannel;
import io.netty.handler.codec.http.HttpObjectAggregator;
import io.netty.handler.codec.http.HttpServerCodec;
import io.netty.handler.codec.http.websocketx.WebSocketServerProtocolHandler;
import io.netty.handler.stream.ChunkedWriteHandler;

public class WSServerInitialzer extends ChannelInitializer<SocketChannel> {

	@Override
	protected void initChannel(SocketChannel ch) throws Exception {
		ChannelPipeline pipeline = ch.pipeline();
		
		// websocket 基於http協議，所以要有http編解碼器
		pipeline.addLast(new HttpServerCodec());
		// 對寫大資料流的支援 
		pipeline.addLast(new ChunkedWriteHandler());
		// 對httpMessage進行聚合，聚合成FullHttpRequest或FullHttpResponse
		// 幾乎在netty中的程式設計，都會使用到此hanler
		pipeline.addLast(new HttpObjectAggregator(1024*64));
		
		// ====================== 以上是用於支援http協議    ======================
		
		// ====================== 以下是支援httpWebsocket ======================
		
		/**
		 * websocket 伺服器處理的協議，用於指定給客戶端連線訪問的路由 : /ws
		 * 本handler會幫你處理一些繁重的複雜的事
		 * 會幫你處理握手動作： handshaking（close, ping, pong） ping + pong = 心跳
		 * 對於websocket來講，都是以frames進行傳輸的，不同的資料型別對應的frames也不同
		 */
		pipeline.addLast(new WebSocketServerProtocolHandler("/ws"));
		
		// 自定義的handler
		pipeline.addLast(new ChatHandler());
	}
}
 

handler

package com.netty.websocket;

import java.time.LocalDateTime;

import io.netty.channel.Channel;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.SimpleChannelInboundHandler;
import io.netty.channel.group.ChannelGroup;
import io.netty.channel.group.DefaultChannelGroup;
import io.netty.handler.codec.http.websocketx.TextWebSocketFrame;
import io.netty.util.concurrent.GlobalEventExecutor;

/**
 * 
 * @Description: 處理訊息的handler
 * TextWebSocketFrame： 在netty中，是用於為websocket專門處理文字的物件，frame是訊息的載體
 */
public class ChatHandler extends SimpleChannelInboundHandler<TextWebSocketFrame> {

	// 用於記錄和管理所有客戶端的channle
	private static ChannelGroup clients = 
			new DefaultChannelGroup(GlobalEventExecutor.INSTANCE);
	
	@Override
	protected void channelRead0(ChannelHandlerContext ctx, TextWebSocketFrame msg) 
			throws Exception {
		// 獲取客戶端傳輸過來的訊息
		String content = msg.text();
		System.out.println("接受到的資料：" + content);
		
		for (Channel channel: clients) {
			channel.writeAndFlush(
				new TextWebSocketFrame(
						"[伺服器在]" + LocalDateTime.now()
						+ "接受到訊息, 訊息為：" + content));
		}
		// 下面這個方法，和上面的for迴圈，一致
		/*clients.writeAndFlush(
				new TextWebSocketFrame(
						"[伺服器在]" + LocalDateTime.now() 
						+ "接受到訊息, 訊息為：" + content));*/
		
	}

	/**
	 * 當客戶端連線服務端之後（開啟連線）
	 * 獲取客戶端的channle，並且放到ChannelGroup中去進行管理
	 */
	@Override
	public void handlerAdded(ChannelHandlerContext ctx) throws Exception {
		clients.add(ctx.channel());
	}

	@Override
	public void handlerRemoved(ChannelHandlerContext ctx) throws Exception {
		// 當觸發handlerRemoved，ChannelGroup會自動移除對應客戶端的channel
//		clients.remove(ctx.channel());
		System.out.println("客戶端斷開，channle對應的長id為：" 
							+ ctx.channel().id().asLongText());
		System.out.println("客戶端斷開，channle對應的短id為：" 
							+ ctx.channel().id().asShortText());
	}
}
 

html

<!DOCTYPE html>
<html>

	<head>
		<meta charset="utf-8" />
		<title></title>
	</head>

	<body>

		<div>傳送訊息:</div>
		<input type="text" id="msgContent" />
		<input type="button" value="點我傳送" onclick="CHAT.chat()" />

		<div>接受訊息：</div>
		<div id="receiveMsg" style="background-color: gainsboro;"></div>

		<script type="application/javascript">
			window.CHAT = {
				socket: null,
				init: function() {
					if(window.WebSocket) {
						CHAT.socket = new WebSocket("ws://localhost:8088/ws");
						CHAT.socket.onopen = function() {
								console.log("連線建立成功...");
							},
							CHAT.socket.onclose = function() {
								console.log("連線關閉...");
							},
							CHAT.socket.onerror = function() {
								console.log("發生錯誤...");
							},
							CHAT.socket.onmessage = function(e) {
								console.log("接受到訊息：" + e.data);
								var receiveMsg = document.getElementById("receiveMsg");
								var html = receiveMsg.innerHTML;
								receiveMsg.innerHTML = html + "<br/>" + e.data;
							}
					} else {
						alert("瀏覽器不支援websocket協議...");
					}
				},
				chat: function() {
					var msg = document.getElementById("msgContent");
					CHAT.socket.send(msg.value);
					document.getElementById("msgContent").value = '';
				}
			};

			CHAT.init();
		</script>
	</body>

</html>

測試