如何使用Netty实现Http服务器

作者:鱼仔
博客首页: codeease.top (opens new window)
公众号:Java鱼仔

# 引言

之前在看XxlJob源码的时候，发现他用Netty实现了一个Http服务器，用来做调度中心和执行器之间的通信。这篇文章我们就用Netty去实现一个Http服务器。同时加深对Netty的理解。

netty版本选择4.1.90.Final

<dependency>
    <groupId>io.netty</groupId>
    <artifactId>netty-codec-http</artifactId>
    <version>4.1.90.Final</version>
</dependency>

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# 服务端搭建

整体的搭建流程和之前写TCP的例子是一样的，定义bossGroup和workerGroup，再通过ServerBootstrap组装group，channel和handler。在ChannelPipeline中，先添加了一个netty提供的处理HTTP的编码器HttpServerCodec，然后再添加一个自定义的编码处理器，当接收到请求的时候，就在这个自定义的编码处理器中进行逻辑处理。

package com.spring.ease.example.netty;

import io.netty.bootstrap.ServerBootstrap;
import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
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;

/**
 * @author by: 鱼仔
 * @ClassName: FirstHttpServer
 * @Description:
 * @Date: 2024/11/8 15:32
 */
public class FirstHttpServer {

    public static void main(String[] args) {
        NioEventLoopGroup bossGroup = new NioEventLoopGroup();
        NioEventLoopGroup workerGroup = new NioEventLoopGroup();
        try {
            ServerBootstrap serverBootstrap = new ServerBootstrap();
            serverBootstrap.group(bossGroup, workerGroup)
                    .channel(NioServerSocketChannel.class)
                    .childHandler(new ChannelInitializer<SocketChannel>() {
                        @Override
                        protected void initChannel(SocketChannel socketChannel) throws Exception {
                            ChannelPipeline pipeline = socketChannel.pipeline();
                            // netty提供的处理HTTP的编码器
                            pipeline.addLast("httpServerCodec", new HttpServerCodec());
                            // 增加一个自定义的编码处理器
                            pipeline.addLast("httpServerHandler",new MyHttpServerHandler());

                        }
                    });
            ChannelFuture channelFuture = serverBootstrap.bind(8080).sync();
            System.out.println("初始化完成，运行端口为：8080");
            channelFuture.channel().closeFuture().sync();

        } catch (InterruptedException e) {
            throw new RuntimeException(e);
        } finally {
            bossGroup.shutdownGracefully();
            workerGroup.shutdownGracefully();
        }

    }

    private static class MyHttpServerHandler extends SimpleChannelInboundHandler<HttpObject> {

        @Override
        protected void channelRead0(ChannelHandlerContext channelHandlerContext, HttpObject httpObject) throws Exception {
            // 如果传输的是Http请求，才进行处理
            if (httpObject instanceof HttpRequest) {

                HttpRequest request = (HttpRequest) httpObject;
                String uri = request.uri();
                System.out.println("uri = " + uri);

                // 跳过favicon.ico
                String faviconUrl = "/favicon.ico";
                if (faviconUrl.equals(uri)){
                    return;
                }

                //回复信息给浏览器 [http协议]

                ByteBuf content = Unpooled.copiedBuffer("hello, 我是服务器", CharsetUtil.UTF_8);

                //构造一个http的相应，即 httpresponse
                FullHttpResponse response = new DefaultFullHttpResponse(HttpVersion.HTTP_1_1, HttpResponseStatus.OK, content);

                response.headers().set(HttpHeaderNames.CONTENT_TYPE, "text/plain; charset=UTF-8");
                response.headers().set(HttpHeaderNames.CONTENT_LENGTH, content.readableBytes());

                //将构建好 response返回
                channelHandlerContext.writeAndFlush(response);
            }
        }
    }
}

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