pom 依赖

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <groupId>com.example</groupId>
    <artifactId>netty-http</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>netty :: Http</name>
    <description>netty实现高性能http服务器</description>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
        <netty-all.version>4.1.100.Final</netty-all.version>
        <logback.version>1.1.7</logback.version>
        <commons.codec.version>1.10</commons.codec.version>
        <fastjson.version>1.2.51</fastjson.version>
        <java.version>17</java.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>io.netty</groupId>
            <artifactId>netty-all</artifactId>
            <version>4.1.100.Final</version>
        </dependency>
        <dependency>
            <groupId>ch.qos.logback</groupId>
            <artifactId>logback-classic</artifactId>
            <version>${logback.version}</version>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.18.2</version>
            <scope>provided</scope>
        </dependency>
        <dependency>
            <groupId>commons-codec</groupId>
            <artifactId>commons-codec</artifactId>
            <version>${commons.codec.version}</version>
        </dependency>
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>fastjson</artifactId>
            <version>${fastjson.version}</version>
        </dependency>

    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>3.7.0</version>
                <configuration>
                    <source>1.8</source>
                    <target>1.8</target>
                    <encoding>utf-8</encoding>
                </configuration>
            </plugin>
        </plugins>
    </build>


</project>

Server

package com.example.netty;

import org.slf4j.LoggerFactory;
import org.slf4j.Logger;
import io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.Channel;
import io.netty.channel.ChannelOption;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.nio.NioServerSocketChannel;
import io.netty.handler.logging.LogLevel;
import io.netty.handler.logging.LoggingHandler;

public final class HttpServer {
    private static final Logger logger = LoggerFactory.getLogger(HttpServer.class);
// 创建一个日志记录器实例，用于记录日志信息。
    static final int PORT = 8888;
// 定义服务器监听的端口号为8888。
    public static void main(String[] args) throws Exception {
        /*
        bossGroup：这个事件循环组专门用于接受客户端的连接。在你的代码中，bossGroup 是通过 new NioEventLoopGroup(1) 创建的，
        这意味着它只有一个线程。这个单线程（或单个EventLoop）将负责监听服务器端口，并接受所有进入的连接。
        由于它只处理连接的接受，而不处理其他I/O操作，通常一个线程就足够了，这也是为什么你看到创建时传递了 1 作为参数。
        workerGroup：这个事件循环组用于处理已被 bossGroup 接受的连接之后的所有I/O操作。
        例如，它将负责读取请求数据、处理请求和发送响应。在你的代码中，workerGroup 是通过 new NioEventLoopGroup() 创建的，
        没有指定线程数量，这意味着Netty将根据默认的I/O工作器数量来创建EventLoops。这个组可以根据你的服务器硬件和负载情况配置多个线程，
        以提高并发处理能力。
         */
        EventLoopGroup bossGroup = new NioEventLoopGroup(1); // 监听端口
        EventLoopGroup workerGroup = new NioEventLoopGroup(5); // 处理连接
        try {
            ServerBootstrap b = new ServerBootstrap();
            // 使用ServerBootstrap辅助启动类来初始化服务器。
            b.option(ChannelOption.SO_BACKLOG, 1024);
            // 设置服务器可接受的连接队列大小为1024。
            b.childOption(ChannelOption.TCP_NODELAY, true);
            // 设置TCP_NODELAY选项为true，禁用Nagle算法，确保数据立即发送。
            b.childOption(ChannelOption.SO_KEEPALIVE, true);
            // 设置SO_KEEPALIVE选项为true，启用TCP保活机制。
            b.group(bossGroup, workerGroup)
                    // 设置接受连接的事件循环组和处理连接的事件循环组。
                    .channel(NioServerSocketChannel.class)
                    // 设置用于创建服务器通道的类。
                    .handler(new LoggingHandler(LogLevel.INFO))
                    // 添加日志处理器，记录服务器的日志信息。
                    .childHandler(new HttpServerInitializer());
            // 设置用于初始化每个新连接的Channel的ChannelInitializer。
            Channel ch = b.bind(PORT).sync().channel();
            // 绑定服务器到指定端口，并同步等待直到绑定成功。
            logger.info("Netty http server listening on port " + PORT);
            // 记录日志信息，告知服务器正在监听指定端口。
            ch.closeFuture().sync();
            // 等待直到Channel关闭。
        } finally {
            bossGroup.shutdownGracefully();
            // 优雅地关闭bossGroup，释放资源。
            workerGroup.shutdownGracefully();
            // 优雅地关闭workerGroup，释放资源。
        }
    }
}

ServerHandler

package com.example.netty;

import java.util.Date;
import java.util.List;
import java.util.Map;
import java.util.Objects;

import com.example.netty.pojo.User;
import com.example.netty.serialize.impl.JSONSerializer;
import io.netty.channel.*;
import io.netty.handler.codec.http.*;
import io.netty.util.AsciiString;
import org.apache.commons.codec.Charsets;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import static io.netty.handler.codec.http.HttpMethod.GET;
import static io.netty.handler.codec.http.HttpMethod.POST;

/**
 * @author pengtao
 */
public class HttpServerHandler extends SimpleChannelInboundHandler<HttpObject> {
    private static final Logger logger = LoggerFactory.getLogger(HttpServerHandler.class);
    private static final String FAVICON_ICO = "/favicon.ico";
    private static final AsciiString CONTENT_TYPE_HDR = AsciiString.cached("Content-Type");
    private static final AsciiString CONTENT_LENGTH_HDR = AsciiString.cached("Content-Length");
    private static final AsciiString CONNECTION_HDR = AsciiString.cached("Connection");
    private static final AsciiString KEEP_ALIVE_VAL = AsciiString.cached("keep-alive");

    private HttpRequest request;
    private HttpHeaders headers;

    @Override
    protected void channelRead0(ChannelHandlerContext ctx, HttpObject msg) throws Exception {
        // 检查是否为HttpRequest对象
        if (!(msg instanceof HttpRequest)) {
            return; // 如果不是HttpRequest，不进行处理
        }
        // 将HttpObject转换为HttpRequest对象
        request = (HttpRequest) msg;
        // 从HttpRequest对象中获取HttpHeaders
        headers = request.headers();
        // 调用自定义方法来进一步处理请求
        handleRequest(ctx); // ctx是ChannelHandlerContext对象，提供了对Channel的引用
    }

    private void handleRequest(ChannelHandlerContext ctx) throws Exception {
        String uri = request.uri();
        if (uri.equals(FAVICON_ICO)) {
            return;
        }
        HttpMethod method = request.method();
        User user = new User();
        user.setUserName("pengtao");
        user.setDate(new Date());
        user.setMethod(method.name());
        if (method.equals(GET)) {
            handleGetRequest();
        } else if (method.equals(POST)) {
            handlePostRequest(ctx);
        } else {
            throw new UnsupportedOperationException("HTTP method " + method + " is not supported");
        }
        writeResponse(ctx, serializeUser(user));
    }

    private void handleGetRequest() {
        logger.info("get请求....");
        QueryStringDecoder queryDecoder = new QueryStringDecoder(request.uri(), Charsets.UTF_8);
        for (Map.Entry<String, List<String>> param : queryDecoder.parameters().entrySet()) {
            for (String value : param.getValue()) {
                logger.info("{}={}", param.getKey(), value);
            }
        }
    }

    private void handlePostRequest(ChannelHandlerContext ctx) throws Exception {
        logger.info("post请求....");
        dealWithContentType(ctx);
    }

    private void writeResponse(ChannelHandlerContext ctx, byte[] content) {
        FullHttpResponse response = new DefaultFullHttpResponse(HttpVersion.HTTP_1_1, HttpResponseStatus.OK);
        response.content().writeBytes(content);
        response.headers().set(CONTENT_TYPE_HDR, "application/json; charset=UTF-8");
        response.headers().set(CONTENT_LENGTH_HDR, response.content().readableBytes());
        boolean keepAlive = HttpUtil.isKeepAlive(request);
        response.headers().set(CONNECTION_HDR, keepAlive ? KEEP_ALIVE_VAL : null);
        ctx.writeAndFlush(response)
                .addListener(keepAlive ? ChannelFutureListener.CLOSE : ChannelFutureListener.CLOSE_ON_FAILURE);
    }

    private byte[] serializeUser(User user) {
        try {
            return new JSONSerializer().serialize(user);
        } catch (Exception e) {
            logger.error("Error serializing user", e);
            throw e;
        }
    }

    private void dealWithContentType(ChannelHandlerContext ctx) throws Exception {
        String contentType = getContentType();
        if (Objects.isNull(contentType)) return;
        switch (Objects.requireNonNull(contentType)) {
            case "application/json":
                parseJsonRequest(ctx);
                break;
            case "application/x-www-form-urlencoded":
                parseFormRequest(ctx);
                break;
            case "multipart/form-data":
                parseMultipartRequest(ctx);
                break;
            default:
                logger.warn("Unsupported content type: {}", contentType);
                sendError(ctx);
                break;
        }
    }

    private String getContentType() {
        return headers.get(CONTENT_TYPE_HDR) == null ? null : headers.get(CONTENT_TYPE_HDR).toString().split(";")[0].trim();
    }

    private void parseJsonRequest(ChannelHandlerContext ctx) throws Exception {
    }

    private void parseFormRequest(ChannelHandlerContext ctx) throws Exception {

    }

    private void parseMultipartRequest(ChannelHandlerContext ctx) throws Exception {

    }

    private void sendError(ChannelHandlerContext ctx) {
        FullHttpResponse response = new DefaultFullHttpResponse(HttpVersion.HTTP_1_1, HttpResponseStatus.UNSUPPORTED_MEDIA_TYPE);
        ctx.writeAndFlush(response).addListener(ChannelFutureListener.CLOSE);
    }


    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) {
        logger.error("Exception caught", cause);
        ctx.close();
    }

    @Override
    public void channelReadComplete(ChannelHandlerContext ctx) {
        ctx.flush();
    }
}

HttpServerInitializer

package com.example.netty;

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.HttpServerExpectContinueHandler;


public class HttpServerInitializer extends ChannelInitializer<SocketChannel> {

    @Override
    public void initChannel(SocketChannel ch) {
        ChannelPipeline p = ch.pipeline();
        /**
         * HttpServerCodec是Netty提供的HTTP请求和响应编解码器，
         * 它将处理HTTP请求和响应的编码和解码。
         */
        p.addLast(new HttpServerCodec());

        /**
         * HttpObjectAggregator是Netty提供的处理器，用于聚合HTTP片段，
         * 例如将HttpRequest和随后的HttpContent聚合成一个FullHttpRequest，
         * 便于后续处理。这里设置的聚合字节大小为1MB。
         */
        p.addLast(new HttpObjectAggregator(1024 * 1024));

        /**
         * HttpServerExpectContinueHandler用于处理HTTP 'Expect: 100-continue' 头部，
         * 当客户端发送的请求包含这个头部时，服务器将先发送100 Continue响应，
         * 然后客户端再发送请求体。这可以用于支持需要分块传输的大型请求体。
         */
        p.addLast(new HttpServerExpectContinueHandler());

        /**
         * HttpHelloWorldServerHandler是我们自定义的HTTP请求处理器，
         * 它将根据接收到的HTTP请求生成响应。
         */
        p.addLast(new HttpServerHandler());
    }

源码 demo:https://github.com/Breeze1203/netty-learning/tree/master/netty-http