1：pom.xml配置

		<dependency><groupId>io.netty</groupId><artifactId>netty-all</artifactId><version>4.1.73.Final</version></dependency>

2：Netty作为HTTP服务器

import io.netty.bootstrap.ServerBootstrap;
import io.netty.buffer.ByteBuf;
import io.netty.channel.*;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioServerSocketChannel;
import io.netty.handler.codec.http.*;
import io.netty.util.CharsetUtil;public class HttpServer {private final int port;public HttpServer(int port) {this.port = port;}public void start() throws Exception {EventLoopGroup bossGroup = new NioEventLoopGroup(1);EventLoopGroup workerGroup = new NioEventLoopGroup();try {ServerBootstrap b = new ServerBootstrap();b.group(bossGroup, workerGroup).channel(NioServerSocketChannel.class).childHandler(new ChannelInitializer<SocketChannel>() {@Overridepublic void initChannel(SocketChannel ch) throws Exception {ChannelPipeline p = ch.pipeline();// 添加 HTTP 编解码器和自定义的ChannelHandlerp.addLast(new HttpServerCodec());p.addLast(new HttpObjectAggregator(1024 * 1024)); // 设置最大聚合大小为1MBp.addLast(new LargeJsonHandler());}}).option(ChannelOption.SO_BACKLOG, 128).childOption(ChannelOption.SO_KEEPALIVE, true);// 绑定端口，开始接受进来的连接ChannelFuture f = b.bind(port).sync();// 等待服务器 socket 关闭f.channel().closeFuture().sync();} finally {workerGroup.shutdownGracefully();bossGroup.shutdownGracefully();}}public static void main(String[] args) throws Exception {new HttpServer(8080).start();}
}class LargeJsonHandler extends SimpleChannelInboundHandler<FullHttpRequest> {@Overridepublic void channelRead0(ChannelHandlerContext ctx, FullHttpRequest request) throws Exception {if (HttpUtil.is100ContinueExpected(request)) {send100Continue(ctx);}ByteBuf content = request.content();String jsonStr = content.toString(CharsetUtil.UTF_8);// 在这里对 JSON 数据进行处理System.out.println(jsonStr);// 发送响应FullHttpResponse response = new DefaultFullHttpResponse(HttpVersion.HTTP_1_1, HttpResponseStatus.OK);response.headers().set(HttpHeaderNames.CONTENT_TYPE, "text/plain; charset=UTF-8");response.content().writeBytes("OK".getBytes(CharsetUtil.UTF_8));response.headers().set(HttpHeaderNames.CONTENT_LENGTH, response.content().readableBytes());ctx.writeAndFlush(response);}private static void send100Continue(ChannelHandlerContext ctx) {FullHttpResponse response = new DefaultFullHttpResponse(HttpVersion.HTTP_1_1, HttpResponseStatus.CONTINUE);ctx.writeAndFlush(response);}@Overridepublic void channelReadComplete(ChannelHandlerContext ctx) {// 写一个空的buf，并刷新写出区域。完成后关闭sock channel连接。//ctx.writeAndFlush(Unpooled.EMPTY_BUFFER).addListener(ChannelFutureListener.CLOSE);}@Overridepublic void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {cause.printStackTrace();ctx.close();}
}

注意：如果发送的JSO数据如果大于1M，是会分包发送的，每次发送都会执行channelReadComplete方法，所以不可以关闭通道，发送完数据才执行channelRead0方法

3：Netty作为webSocket服务器

package com.example.slave.netty.server;import io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.*;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioServerSocketChannel;
import io.netty.handler.codec.http.HttpObjectAggregator;
import io.netty.handler.codec.http.HttpServerCodec;
import io.netty.handler.codec.http.websocketx.WebSocketServerProtocolHandler;/*** @Description:* @Author: xu* @Data: 2024-2024/1/4-11* @Version: V1.0*/
public class CustomWebSocket {private final int port;public CustomWebSocket(int port) {this.port = port;}public void start() throws Exception {//设置用于连接的boss组， 可在构造器中定义使用的线程数  监听端口接收客户端连接，一个端口一个线程，然后转给worker组//boss组用于监听客户端连接请求，有连接传入时就生成连接channel传给worker，等worker 接收请求 io多路复用，EventLoopGroup bossGroup = new NioEventLoopGroup(1);EventLoopGroup workerGroup = new NioEventLoopGroup();try {ServerBootstrap b = new ServerBootstrap();b.group(bossGroup, workerGroup)//定义使用的通道 可以选择是NIO或者是OIO 代表了worker在处理socket channel时的不同情况。oio只能1对1， nio则没有1对1对关系//当netty要处理长连接时最好使用NIO，不然如果要保证效率 需要创建大量的线程，和io多路复用一致.channel(NioServerSocketChannel.class)//.channel(OioServerSocketChannel.class).childHandler(new ChannelInitializer<SocketChannel>() {@Overridepublic void initChannel(SocketChannel ch) throws Exception {ChannelPipeline p = ch.pipeline();// 添加 HTTP 编解码器和自定义的ChannelHandlerp.addLast(new HttpServerCodec());p.addLast(new HttpObjectAggregator(1024 * 1024)); // 设置最大聚合大小为1MBp.addLast(new WebSocketServerProtocolHandler("/ws", "WebSocket", true, 65536 * 10));p.addLast(new MyWebSocketHandler());}}).option(ChannelOption.SO_BACKLOG, 128).childOption(ChannelOption.SO_KEEPALIVE, true);// 绑定端口，开始接受进来的连接ChannelFuture f = b.bind(port).sync();// 等待服务器 socket 关闭f.channel().closeFuture().sync();} finally {workerGroup.shutdownGracefully();bossGroup.shutdownGracefully();}}}

public class MyWebSocketHandler extends SimpleChannelInboundHandler<TextWebSocketFrame> {public static ChannelGroup channelGroup;static {channelGroup = new DefaultChannelGroup(GlobalEventExecutor.INSTANCE);}//客户端与服务器建立连接的时候触发，@Overridepublic void channelActive(ChannelHandlerContext ctx) throws Exception {System.out.println("与客户端建立连接，通道开启！");//添加到channelGroup通道组channelGroup.add(ctx.channel());}//客户端与服务器关闭连接的时候触发，@Overridepublic void channelInactive(ChannelHandlerContext ctx) throws Exception {System.out.println("与客户端断开连接，通道关闭！");channelGroup.remove(ctx.channel());}@Overridepublic void channelReadComplete(ChannelHandlerContext ctx) {// 写一个空的buf，并刷新写出区域。完成后关闭sock channel连接。ctx.writeAndFlush(Unpooled.EMPTY_BUFFER).addListener(ChannelFutureListener.CLOSE);}
​@Overridepublic void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) {// 关闭发生异常的连接ctx.close();}//服务器接受客户端的数据信息，@Overrideprotected void channelRead0(ChannelHandlerContext ctx, TextWebSocketFrame msg){System.out.println("服务器收到的数据：" + msg.text());//sendMessage(ctx);sendAllMessage();}//给固定的人发消息private void sendMessage(ChannelHandlerContext ctx) {String message = "你好，"+ctx.channel().localAddress()+" 给固定的人发消息";ctx.channel().writeAndFlush(new TextWebSocketFrame(message));}//发送群消息,此时其他客户端也能收到群消息private void sendAllMessage(){String message = "我是服务器，这里发送的是群消息";channelGroup.writeAndFlush( new TextWebSocketFrame(message));}
}