netty hello_world

curl --location --request GET 'http://localhost:8089'

创建一个Springboot project

• pom.xml 添加netty 依赖

        <!-- https://mvnrepository.com/artifact/io.netty/netty-all -->
<dependency>
    <groupId>io.netty</groupId>
    <artifactId>netty-all</artifactId>
    <version>4.1.69.Final</version>
</dependency>

NettyServer

import io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.Channel;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelOption;
import io.netty.channel.ChannelPipeline;
import io.netty.channel.EventLoopGroup;
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.HttpServerCodec;
import io.netty.handler.logging.LogLevel;
import io.netty.handler.logging.LoggingHandler;

public class NettyServer {
	private static final int PORT = 8089;

	public static void main(String[] args) {

		// Configure the server.
		EventLoopGroup bossGroup = new NioEventLoopGroup(1);
		EventLoopGroup workerGroup = new NioEventLoopGroup();
		try {
			ServerBootstrap b = new ServerBootstrap();
			b.option(ChannelOption.SO_BACKLOG, 1024);
			b.group(bossGroup, workerGroup)
				.channel(NioServerSocketChannel.class)
				.handler(new LoggingHandler(LogLevel.INFO))
				.childHandler(new ChannelInitializer<SocketChannel>() {
					@Override
					protected void initChannel(SocketChannel socketChannel) throws Exception {
						ChannelPipeline p = socketChannel.pipeline();
						p.addLast(new HttpServerCodec());
						p.addLast(new HttpHelloWorldServerHandler());
					}
				});

			Channel ch = b.bind(PORT).sync().channel();
			ch.closeFuture().sync();
		} catch (InterruptedException e) {
			e.printStackTrace();
		} finally {
			bossGroup.shutdownGracefully();
			workerGroup.shutdownGracefully();
		}
	}
}

HttpHelloWorldServerHandler

import static io.netty.handler.codec.http.HttpHeaderNames.*;
import static io.netty.handler.codec.http.HttpHeaderValues.*;
import static io.netty.handler.codec.http.HttpHeaderValues.KEEP_ALIVE;
import static io.netty.handler.codec.http.HttpResponseStatus.*;

import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelFutureListener;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.SimpleChannelInboundHandler;
import io.netty.handler.codec.http.DefaultFullHttpResponse;
import io.netty.handler.codec.http.FullHttpResponse;
import io.netty.handler.codec.http.HttpObject;
import io.netty.handler.codec.http.HttpRequest;
import io.netty.handler.codec.http.HttpUtil;

public class HttpHelloWorldServerHandler extends SimpleChannelInboundHandler<HttpObject> {
    private static final byte[] CONTENT = { 'H', 'e', 'l', 'l', 'o', ' ', 'W', 'o', 'r', 'l', 'd' };

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

    @Override
    public void channelRead0(ChannelHandlerContext ctx, HttpObject msg) {
        if (msg instanceof HttpRequest) {

            HttpRequest req = (HttpRequest) msg;

            boolean keepAlive = HttpUtil.isKeepAlive(req);
			System.out.println("=======================");
			System.out.println("keep alive is:"+keepAlive);
			
            FullHttpResponse response = new DefaultFullHttpResponse(req.protocolVersion(), OK,
                                                                    Unpooled.wrappedBuffer(CONTENT));
            response.headers()
                    .set(CONTENT_TYPE, TEXT_PLAIN)
                    .setInt(CONTENT_LENGTH, response.content().readableBytes());

            if (keepAlive) {
                if (!req.protocolVersion().isKeepAliveDefault()) {
                    response.headers().set(CONNECTION, KEEP_ALIVE);
                }
            } else {
                // Tell the client we're going to close the connection.
                response.headers().set(CONNECTION, CLOSE);
            }

            ChannelFuture f = ctx.write(response);

            if (!keepAlive) {
                f.addListener(ChannelFutureListener.CLOSE);
            }
        }
    }

    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) {
        cause.printStackTrace();
        ctx.close();
    }
}

run or debug NettyServer.main

参考文章