java ｜ http 协议 「SimpleChannelInboundHandler」

netty 自带 http 解码器。

new HttpServerCodec()

使用 new HttpServerCodec() 会将数据解析成两个

• DefaultHttpRequest
• HttpContent

该处理器既是出站处理器也是入站处理器。

所以，接收数据可以写成

服务端

package com.redisc;

import io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandlerAdapter;
import io.netty.channel.ChannelInitializer;
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.DefaultHttpRequest;
import io.netty.handler.codec.http.HttpContent;
import io.netty.handler.codec.http.HttpServerCodec;
import io.netty.handler.logging.LogLevel;
import io.netty.handler.logging.LoggingHandler;
import lombok.extern.slf4j.Slf4j;

import java.io.IOException;


@Slf4j
public class Server {

    public static void main(String[] args) throws IOException {
        NioEventLoopGroup boss = new NioEventLoopGroup();
        NioEventLoopGroup worker = new NioEventLoopGroup();

        try {
            ServerBootstrap serverBootstrap = new ServerBootstrap();
            serverBootstrap.channel(NioServerSocketChannel.class);
            serverBootstrap.group(boss, worker);
            serverBootstrap.childHandler(new ChannelInitializer<SocketChannel>() {
                @Override
                protected void initChannel(SocketChannel socketChannel) throws Exception {
                    socketChannel.pipeline().addLast(new LoggingHandler(LogLevel.DEBUG));
                    socketChannel.pipeline().addLast(new HttpServerCodec());
                    socketChannel.pipeline().addLast(new ChannelInboundHandlerAdapter() {
                        @Override
                        public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
                            if (msg instanceof DefaultHttpRequest) { // 请求头，请求行

                            } else if (msg instanceof HttpContent) { // 请求体

                            }
                        }
                    });
                }
            });
            ChannelFuture channelFuture = serverBootstrap.bind(8000).sync();
            channelFuture.channel().closeFuture().sync();
        } catch (InterruptedException e) {
            log.error("error", e);
        } finally {
            boss.shutdownGracefully();
            worker.shutdownGracefully();
        }

    }
}

但是，每次我们用 if else 判断可能不优雅，比如，有时候，我们只需要请求体，所以可以简化成

直接在浏览器访问 http://127.0.0.1:8000/index.html

package com.redisc;

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.*;
import io.netty.handler.logging.LogLevel;
import io.netty.handler.logging.LoggingHandler;
import lombok.extern.slf4j.Slf4j;

import java.io.IOException;

import static io.netty.handler.codec.http.HttpHeaderNames.CONTENT_LENGTH;


@Slf4j
public class Server {

    public static void main(String[] args) throws IOException {
        NioEventLoopGroup boss = new NioEventLoopGroup();
        NioEventLoopGroup worker = new NioEventLoopGroup();

        try {
            ServerBootstrap serverBootstrap = new ServerBootstrap();
            serverBootstrap.channel(NioServerSocketChannel.class);
            serverBootstrap.group(boss, worker);
            serverBootstrap.childHandler(new ChannelInitializer<SocketChannel>() {
                @Override
                protected void initChannel(SocketChannel socketChannel) throws Exception {
                    socketChannel.pipeline().addLast(new LoggingHandler(LogLevel.DEBUG));
                    socketChannel.pipeline().addLast(new HttpServerCodec());
                    socketChannel.pipeline().addLast(new SimpleChannelInboundHandler<HttpRequest>() {
                        @Override
                        protected void channelRead0(ChannelHandlerContext channelHandlerContext, HttpRequest msg) throws Exception {
                            // 返回响应

                            DefaultFullHttpResponse defaultHttpResponse = new DefaultFullHttpResponse(msg.protocolVersion(), HttpResponseStatus.OK);
                            byte[] b = "<h1>hello</h1>".getBytes();
                            defaultHttpResponse.headers().setInt(CONTENT_LENGTH, b.length);
                            defaultHttpResponse.content().writeBytes(b); // 不加这一句的话，chrome 就会一直等着，因为，他不知道数据长度是多长

                            // 写回响应
                            channelHandlerContext.writeAndFlush(defaultHttpResponse);
                        }
                    });
                }
            });
            ChannelFuture channelFuture = serverBootstrap.bind(8000).sync();
            channelFuture.channel().closeFuture().sync();
        } catch (InterruptedException e) {
            log.error("error", e);
        } finally {
            boss.shutdownGracefully();
            worker.shutdownGracefully();
        }

    }
}

通过使用简单处理器，SimpleChannelInboundHandler 中传递 HttpContent 里面就可以直接收 HttpContent 的内容了。