Netty入门之WebSocket初体验

什么是Netty

• 高性能 事件驱动、异步非阻塞
• 基于NIO的客户端、服务端编程框架
• 稳定性和伸缩性

Netty使用场景

• 高性能领域
• 多线程并发领域
• 异步通信领域

IO通信

BIO通信

同步阻塞IO

• 一个线程负责连接
• 一个请求一应答
• 缺乏弹性伸缩能力
  BIO通信模型
  典型的就是tomcat
  

伪异步IO通信

同步阻塞IO

• 线程池负责连接
• M请求N连接
• 线程池阻塞
  伪异步IO通信模型
  

NIO模型

同步非阻塞IO

• M请求1连接
• 缓冲区Buffer
• 通道Channel
• 多路复用器Selector

AIO通信

异步非阻塞IO

• 连接注册读写事件和回调函数
• 读写方法异步
• 主动通知程序

Netty实现WebSocket

项目地址： https://github.com/ghostKang/netty-study

maven依赖

        
            io.netty
            netty-all
            4.1.16.Final
        

启动类

import handler.MyWebSocketChannelHandler;
import io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.Channel;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.nio.NioServerSocketChannel;

/**
 * 程序的入口，负责启动应用
 *
 * Created by Yuk on 2019/1/2.
 */
public class Main {

    public static void main(String[] args) {
        EventLoopGroup boosGroup = new NioEventLoopGroup();
        EventLoopGroup workGroup = new NioEventLoopGroup();

        try {
            ServerBootstrap b = new ServerBootstrap();
            b.group(boosGroup,workGroup);
            b.channel(NioServerSocketChannel.class);
            b.childHandler(new MyWebSocketChannelHandler());// 调用自己封装的处理类
            System.out.println("服务端开启等待客户端连接...");
            Channel ch = b.bind(9998).sync().channel();
            ch.closeFuture().sync();

        }catch (Exception e){
            e.printStackTrace();
        }finally {
            // 优雅地退出程序
            boosGroup.shutdownGracefully();
            workGroup.shutdownGracefully();
        }

    }
}

自己封装的处理类

MyWebSocketChannelHandler .java

package handler;

import io.netty.channel.ChannelInitializer;
import io.netty.channel.socket.SocketChannel;
import io.netty.handler.codec.http.HttpObjectAggregator;
import io.netty.handler.codec.http.HttpServerCodec;
import io.netty.handler.stream.ChunkedWriteHandler;


/**
 * 初始化连接时候的各个组件
 *
 * Created by Yuk on 2019/1/2.
 */
public class MyWebSocketChannelHandler extends ChannelInitializer {

    @Override
    protected void initChannel(SocketChannel e) throws Exception {
        e.pipeline().addLast("http-codec",new HttpServerCodec());
        e.pipeline().addLast("aggregator",new HttpObjectAggregator(65536));
        e.pipeline().addLast("http-chunked",new ChunkedWriteHandler());
        e.pipeline().addLast("handler",new MyWebSocketHandler());// 调用自己封装的处理类
    }
}

MyWebSocketHandler.java

package handler;

import config.NettyConfig;
import io.netty.buffer.ByteBuf;
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.FullHttpRequest;
import io.netty.handler.codec.http.HttpResponseStatus;
import io.netty.handler.codec.http.HttpVersion;
import io.netty.handler.codec.http.websocketx.*;
import io.netty.util.CharsetUtil;

import java.util.Date;

/**
 * 接受/处理/响应客户端webSocket请求的核心业务处理类
 *
 * Created by Yuk on 2019/1/1.
 */
public class MyWebSocketHandler extends SimpleChannelInboundHandler