Netty执行流程分析与重要组件介绍

一、环境搭建

创建工程，引入Netty依赖

二、基于Netty的请求响应Demo

1、TestHttpServerHandle  处理器。读取客户端发送过来的请求，并且向客户端返回hello world响应

package com.example.firstexample;

import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.SimpleChannelInboundHandler;
import io.netty.handler.codec.http.*;
import io.netty.util.CharsetUtil;

public class TestHttpServerHandle  extends SimpleChannelInboundHandler<HttpObject>{

    //读取客户端发送过来的请求，并且向客户端返回响应
    protected void channelRead0(ChannelHandlerContext channelHandlerContext, HttpObject httpObject) throws Exception {

        if(httpObject instanceof  HttpRequest){
            ByteBuf content = Unpooled.copiedBuffer("Hello world", CharsetUtil.UTF_8);
            FullHttpResponse response = new DefaultFullHttpResponse(HttpVersion.HTTP_1_1, HttpResponseStatus.OK,content);
            response.headers().set(HttpHeaderNames.CONTENT_TYPE,"text/plain");
            response.headers().set(HttpHeaderNames.CONTENT_LENGTH, content.readableBytes());
            //写回客户端
            channelHandlerContext.writeAndFlush(response);
        }

    }
}

　　

　　

2、TestServerInitializer 类

public class TestServerInitializer extends ChannelInitializer<SocketChannel> {
    protected void initChannel(SocketChannel socketChannel) throws Exception {
        ChannelPipeline pipeline =  socketChannel.pipeline();

        pipeline.addLast("httpServerCode", new HttpServerCodec());
        pipeline.addLast("testHttpServerHandler", new TestHttpServerHandle());

    }
}

　

3、TestServer 类

package com.example.firstexample;

import io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.ChannelFuture;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.nio.NioServerSocketChannel;

public class TestServer {

    public static void main(String[] args) throws Exception {

        //bossGroup获取连接
        EventLoopGroup bossGroup = new NioEventLoopGroup();
        //workerGroup处理连接
        EventLoopGroup workerGroup = new NioEventLoopGroup();
        try{
            ServerBootstrap serverBootstrap = new ServerBootstrap();
            //1、启动Bootstrap服务器，服务器关联两个事件循环组bossGroup，workerGroup
            //2、并且关联事件处理器，处理器使用TestServerInitializer定义，如TestServerInitializer里使用了处理器TestHttpServerHandle
            serverBootstrap.group(bossGroup, workerGroup).channel(NioServerSocketChannel.class)
                    .childHandler(new TestServerInitializer());

            ChannelFuture channelFuture = serverBootstrap.bind(8899).sync();
            channelFuture.channel().closeFuture().sync();

        }finally {
            bossGroup.shutdownGracefully();
            workerGroup.shutdownGracefully();
        }

    }
}

　　

　　启动main方法

4、测试

5、总结Netty执行流程

1)启动Bootstrap服务器，服务器关联两个事件循环组bossGroup（获取连接），workerGroup（处理连接）
2)并且关联事件处理器，处理器使用TestServerInitializer定义，如TestServerInitializer里使用了处理器TestHttpServerHandle