Netty搭建简单WebSocket通信

概述

websocket使用主从线程组模型，仅实现浏览器发送数据，服务器接收数据控制台输出并转发给所有连接的客户端

端口绑定8088

代码

主启动类 WSServer.java

package com.imooc.netty.websocket;

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;

/**
 * @Author Sakura
 * @Date 5/8/2019
 **/


public class WSServer {

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

        //创建主从线程组
        EventLoopGroup mainGroup = new NioEventLoopGroup();
        EventLoopGroup subGroup = new NioEventLoopGroup();

        try {
            ServerBootstrap serverBootstrap = new ServerBootstrap();

            serverBootstrap.group(mainGroup,subGroup)
                           .channel(NioServerSocketChannel.class)
                           .childHandler(new WSServerInitializer());

            //绑定端口，同步启动
            ChannelFuture channelFuture = serverBootstrap.bind(8088).sync();

            //监听关闭，同步启动
            channelFuture.channel().closeFuture().sync();
        } finally {
            mainGroup.shutdownGracefully();
            subGroup.shutdownGracefully();
        }
    }
}

初始化器 WSServerInitializer.java

package com.imooc.netty.websocket;

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

/**
 * @Author Sakura
 * @Date 5/8/2019
 **/
public class WSServerInitializer extends ChannelInitializer<SocketChannel> {
    protected void initChannel(SocketChannel socketChannel) throws Exception {

        ChannelPipeline pipeline = socketChannel.pipeline();

        //websoket基于http，所以有http编码解码器
        pipeline.addLast(new HttpServerCodec());
        //对写大数据流的支持
        pipeline.addLast(new ChunkedWriteHandler());
        //对httpMessage进行聚合，聚合成HttpRequest或HttpResponse
        //几乎在Netty的编程都会使用到此handler
        pipeline.addLast(new HttpObjectAggregator(1024*64));


        //====================以上是用于支持Http协议===========================
        /**
         * websocket服务器处理协议，用于指定给客户端访问的路由：/ws (比如  ws://localhost:8088/ws)
         * 本handler会处理以下繁重的事务
         * 握手动作：handshaking(close,ping--请求,pong--响应)
         * websocket都是以frames进行传输，不同数据类型frames也不同
         */
        pipeline.addLast(new WebSocketServerProtocolHandler("/ws"));
        //自定义通信助手类，客户端消息处理与消息回送
        pipeline.addLast(new ChatHandler());


    }
}

自定义助手类 ChatHandler.java

package com.imooc.netty.websocket;

import io.netty.channel.Channel;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.SimpleChannelInboundHandler;
import io.netty.channel.group.ChannelGroup;
import io.netty.channel.group.DefaultChannelGroup;
import io.netty.handler.codec.http.websocketx.TextWebSocketFrame;
import io.netty.util.concurrent.GlobalEventExecutor;

import java.time.LocalDateTime;

/**
 * @Author Sakura
 * @Date 5/8/2019
 * 处理消息的handler
 * TextWebSocketFrame 在netty中专门为websocket处理文本的对象，frame是消息载体
 **/
public class ChatHandler extends SimpleChannelInboundHandler<TextWebSocketFrame> {

    //用于记录和管理所有客户端channel的ChannelGroup
    private static ChannelGroup clients = new DefaultChannelGroup(GlobalEventExecutor.INSTANCE);

    protected void channelRead0(ChannelHandlerContext channelHandlerContext, TextWebSocketFrame msg) throws Exception {

        //获取客户端传输的消息
        String content = msg.text();
        System.out.println("接受到的数据为：" + content);

//        for (Channel channel:clients) {
//            channel.writeAndFlush(
//                    new TextWebSocketFrame("[服务器于"+ LocalDateTime.now()+ "收到消息]：" + content)
//            );
//        }
        //该方法同以上循环
        clients.writeAndFlush(new TextWebSocketFrame("[服务器于"+ LocalDateTime.now()+ "收到消息]：" + content));
    }

    /**
     *客户端连接服务端后(打开链接)
     * 获取客户端channel，并放入ChannelGroup中管理
     */

    @Override
    public void handlerAdded(ChannelHandlerContext ctx) throws Exception {
        clients.add(ctx.channel());
    }

    /**
     * 当触发handlerRemoved方法时，ChannelGroup会自动移除对应客户端的channel
     * 所以无需手动remove
     */

    @Override
    public void handlerRemoved(ChannelHandlerContext ctx) throws Exception {
        //clients.remove(ctx.channel());
        //每个channel都有标是自身的id，分长短。有大型channel时短id可能重复
        System.out.println("客户端断开，channel对应长id为："+ ctx.channel().id().asLongText());
        System.out.println("客户端断开，channel对应短id为："+ ctx.channel().id().asShortText());
    }
}

前端代码

<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8" />
		<title></title>
	</head>
	<body>
		<text>消息发送</text> <br/>
		<input type="text" id="msgSend" />
		<input type="button" value="发送" onclick="CHAT.chat()"/><br/>
		<text>消息接收</text><br/>
		<div id="msgRecv" style="background-color: blanchedalmond;"></div>
		
		<script type="text/javascript">
			window.CHAT = {
				socket:null,
				init:function(){
					if(window.WebSocket){
						
						CHAT.socket = new WebSocket("ws://127.0.0.1:8088/ws");
						CHAT.socket.onopen=function(){
							console.log("建立连接");
						},
						CHAT.socket.onclose=function(){
							console.log("连接关闭")
						},
						CHAT.socket.onerror=function(){
							console.log("发生错误")
						},
						CHAT.socket.onmessage=function(e){
							console.log("收到消息:"+e.data)
							
							var msgRecv = document.getElementById("msgRecv");
							var html = msgRecv.innerHTML;
							msgRecv.innerHTML = html + "<br/>" + e.data;
						}
					}else{
						alert("该浏览器不支持websocket");
					}
				},
	
				chat:function(){
					var msg = document.getElementById("msgSend");
					CHAT.socket.send(msg.value)
				}
			}
			
			CHAT.init()
		</script>
	</body>
</html>

测试

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