Spring boot 集成netty实现websocket通信

一、netty介绍

Netty是由JBOSS提供的一个java开源框架，现为 Github上的独立项目。Netty提供异步的、事件驱动的网络应用程序框架和工具，用以快速开发高性能、高可靠性的网络服务器和客户端程序。也就是说，Netty 是一个基于NIO的客户、服务器端的编程框架，使用Netty 可以确保你快速和简单的开发出一个网络应用，例如实现了某种协议的客户、服务端应用。Netty相当于简化和流线化了网络应用的编程开发过程，例如：基于TCP和UDP的socket服务开发。快速"和"简单"并不用产生维护性或性能上的问题。Netty 是一个吸收了多种协议（包括FTP、SMTP、HTTP等各种二进制文本协议）的实现经验，并经过相当精心设计的项目。最终，Netty 成功的找到了一种方式，在保证易于开发的同时还保证了其应用的性能，稳定性和伸缩性

二、工程搭建

实验目标：实现推送消息给指定的用户

pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <parent>
        <artifactId>springboot-demo</artifactId>
        <groupId>com.et</groupId>
        <version>1.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>

    <artifactId>netty</artifactId>

    <properties>
        <maven.compiler.source>8</maven.compiler.source>
        <maven.compiler.target>8</maven.compiler.target>
    </properties>
    <dependencies>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-autoconfigure</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>io.netty</groupId>
            <artifactId>netty-all</artifactId>
            <version>4.1.87.Final</version>
        </dependency>
        <dependency>
            <groupId>cn.hutool</groupId>
            <artifactId>hutool-all</artifactId>
            <version>5.6.1</version>
        </dependency>
    </dependencies>
</project>

属性文件

server:
  port: 8088

netty server

package com.et.netty.server;

import com.et.netty.config.ProjectInitializer;
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;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;

import javax.annotation.PostConstruct;
import javax.annotation.PreDestroy;
import java.net.InetSocketAddress;

/**
 * @author dongliang7
 * @projectName websocket-parent
 * @ClassName NettyServer.java
 * @description: TODO
 * @createTime 2023年02月06日 16:41:00
 */
@Component
public class NettyServer {
    static final Logger log = LoggerFactory.getLogger(NettyServer.class);

    /**
     * 端口号
     */
    @Value("${webSocket.netty.port:8889}")
    int port;

    EventLoopGroup bossGroup;
    EventLoopGroup workGroup;

    @Autowired
    ProjectInitializer nettyInitializer;

    @PostConstruct
    public void start() throws InterruptedException {
        new Thread(() -> {
            bossGroup = new NioEventLoopGroup();
            workGroup = new NioEventLoopGroup();
            ServerBootstrap bootstrap = new ServerBootstrap();
            // bossGroup辅助客户端的tcp连接请求, workGroup负责与客户端之前的读写操作
            bootstrap.group(bossGroup, workGroup);
            // 设置NIO类型的channel
            bootstrap.channel(NioServerSocketChannel.class);
            // 设置监听端口
            bootstrap.localAddress(new InetSocketAddress(port));
            // 设置管道
            bootstrap.childHandler(nettyInitializer);

            // 配置完成，开始绑定server，通过调用sync同步方法阻塞直到绑定成功
            ChannelFuture channelFuture = null;
            try {
                channelFuture = bootstrap.bind().sync();
                log.info("Server started and listen on:{}", channelFuture.channel().localAddress());
                // 对关闭通道进行监听
                channelFuture.channel().closeFuture().sync();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }).start();
    }

    /**
     * 释放资源
     */
    @PreDestroy
    public void destroy() throws InterruptedException {
        if (bossGroup != null) {
            bossGroup.shutdownGracefully().sync();
        }
        if (workGroup != null) {
            workGroup.shutdownGracefully().sync();
        }
    }
}

ProjectInitializer

初始化，设置websocket handler

package com.et.netty.config;

import com.et.netty.handler.WebSocketHandler;
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.codec.serialization.ObjectEncoder;
import io.netty.handler.stream.ChunkedWriteHandler;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;

/**
 * @author dongliang7
 * @projectName websocket-parent
 * @ClassName ProjectInitializer.java
 * @description: 管道配置
 * @createTime 2023年02月06日 16:43:00
 */
@Component
public class ProjectInitializer extends ChannelInitializer<SocketChannel> {

    /**
     * webSocket协议名
     */
    static final String WEBSOCKET_PROTOCOL = "WebSocket";

    /**
     * webSocket路径
     */
    @Value("${webSocket.netty.path:/webSocket}")
    String webSocketPath;
    @Autowired
    WebSocketHandler webSocketHandler;

    @Override
    protected void initChannel(SocketChannel socketChannel) throws Exception {
        // 设置管道
        ChannelPipeline pipeline = socketChannel.pipeline();
        // 流水线管理通道中的处理程序（Handler），用来处理业务
        // webSocket协议本身是基于http协议的，所以这边也要使用http编解码器
        pipeline.addLast(new HttpServerCodec());
        pipeline.addLast(new ObjectEncoder());
        // 以块的方式来写的处理器
        pipeline.addLast(new ChunkedWriteHandler());
        pipeline.addLast(new HttpObjectAggregator(8192));
        pipeline.addLast(new WebSocketServerProtocolHandler(webSocketPath, WEBSOCKET_PROTOCOL, true, 65536 * 10));
        // 自定义的handler，处理业务逻辑
        pipeline.addLast(webSocketHandler);
    }
}

WebSocketHandler

package com.et.netty.handler;

import cn.hutool.json.JSONObject;
import cn.hutool.json.JSONUtil;
import com.et.netty.config.NettyConfig;
import com.et.netty.server.NettyServer;
import io.netty.channel.ChannelHandler;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.SimpleChannelInboundHandler;
import io.netty.handler.codec.http.websocketx.TextWebSocketFrame;
import io.netty.util.AttributeKey;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.stereotype.Component;

/**
 * @author dongliang7
 * @projectName websocket-parent
 * @ClassName WebSocketHandler.java
 * @description: TODO
 * @createTime 2023年02月06日 16:44:00
 */
@Component
@ChannelHandler.Sharable
public class WebSocketHandler extends SimpleChannelInboundHandler<TextWebSocketFrame> {
    private static final Logger log = LoggerFactory.getLogger(NettyServer.class);

    /**
     * 一旦连接，第一个被执行
     */
    @Override
    public void handlerAdded(ChannelHandlerContext ctx) throws Exception {
        log.info("有新的客户端链接：[{}]", ctx.channel().id().asLongText());
        // 添加到channelGroup 通道组
        NettyConfig.getChannelGroup().add(ctx.channel());
    }

    /**
     * 读取数据
     */
    @Override
    protected void channelRead0(ChannelHandlerContext ctx, TextWebSocketFrame msg) throws Exception {
        log.info("服务器收到消息：{}", msg.text());

        // 获取用户ID,关联channel
        JSONObject jsonObject = JSONUtil.parseObj(msg.text());
        String uid = jsonObject.getStr("uid");
        NettyConfig.getChannelMap().put(uid, ctx.channel());

        // 将用户ID作为自定义属性加入到channel中，方便随时channel中获取用户ID
        AttributeKey<String> key = AttributeKey.valueOf("userId");
        ctx.channel().attr(key).setIfAbsent(uid);

        // 回复消息
        ctx.channel().writeAndFlush(new TextWebSocketFrame("服务器收到消息啦"));
    }

    @Override
    public void handlerRemoved(ChannelHandlerContext ctx) throws Exception {
        log.info("用户下线了:{}", ctx.channel().id().asLongText());
        // 删除通道
        NettyConfig.getChannelGroup().remove(ctx.channel());
        removeUserId(ctx);
    }

    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
        log.info("异常：{}", cause.getMessage());
        // 删除通道
        NettyConfig.getChannelGroup().remove(ctx.channel());
        removeUserId(ctx);
        ctx.close();
    }

    /**
     * 删除用户与channel的对应关系
     */
    private void removeUserId(ChannelHandlerContext ctx) {
        AttributeKey<String> key = AttributeKey.valueOf("userId");
        String userId = ctx.channel().attr(key).get();
        NettyConfig.getChannelMap().remove(userId);
    }
}

NettyConfig

package com.et.netty.config;

import io.netty.channel.Channel;
import io.netty.channel.group.ChannelGroup;
import io.netty.channel.group.DefaultChannelGroup;
import io.netty.util.concurrent.GlobalEventExecutor;

import java.util.concurrent.ConcurrentHashMap;

/**
 * @author dongliang7
 * @projectName websocket-parent
 * @ClassName NettyConfig.java
 * @description: 管理全局Channel以及用户对应的channel（推送消息）
 * @createTime 2023年02月06日 16:43:00
 */
public class NettyConfig {
    /**
     * 定义全局单利channel组 管理所有channel
     */
    private static volatile ChannelGroup channelGroup = null;

    /**
     * 存放请求ID与channel的对应关系
     */
    private static volatile ConcurrentHashMap<String, Channel> channelMap = null;

    /**
     * 定义两把锁
     */
    private static final Object lock1 = new Object();
    private static final Object lock2 = new Object();


    public static ChannelGroup getChannelGroup() {
        if (null == channelGroup) {
            synchronized (lock1) {
                if (null == channelGroup) {
                    channelGroup = new DefaultChannelGroup(GlobalEventExecutor.INSTANCE);
                }
            }
        }
        return channelGroup;
    }

    public static ConcurrentHashMap<String, Channel> getChannelMap() {
        if (null == channelMap) {
            synchronized (lock2) {
                if (null == channelMap) {
                    channelMap = new ConcurrentHashMap<>();
                }
            }
        }
        return channelMap;
    }

    public static Channel getChannel(String userId) {
        if (null == channelMap) {
            return getChannelMap().get(userId);
        }
        return channelMap.get(userId);
    }
}

controller

package com.et.netty.controller;

import com.et.netty.service.PushMsgService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;


/**
 * @author dongliang7
 * @projectName
 * @ClassName TestController.java
 * @description: TODO
 * @createTime 2023年02月06日 17:48:00
 */
@RestController
@RequestMapping("/push")
public class TestController {
    @Autowired
    PushMsgService pushMsgService;

    /**
     * 推送消息到具体客户端
     * @param uid
     */
    @GetMapping("/{uid}")
    public void pushOne(@PathVariable String uid) {
        pushMsgService.pushMsgToOne(uid, "hello-------------------------");
    }

    /**
     * 推送消息到所有客户端
     */
    @GetMapping("/pushAll")
    public void pushAll() {
        pushMsgService.pushMsgToAll("hello all-------------------------");
    }
}

PushMsgService

package com.et.netty.service;

/**
 * @author dongliang7
 * @projectName websocket-parent
 * @ClassName PushMsgService.java
 * @description: 推送消息接口
 * @createTime 2023年02月06日 16:44:00
 */
public interface PushMsgService {
    /**
     * 推送给指定用户
     */
    void pushMsgToOne(String userId, String msg);

    /**
     * 推送给所有用户
     */
    void pushMsgToAll(String msg);
}

PushMsgServiceImpl

package com.et.netty.service;

import com.et.netty.config.NettyConfig;
import io.netty.channel.Channel;
import io.netty.handler.codec.http.websocketx.TextWebSocketFrame;
import org.springframework.stereotype.Service;


import java.util.Objects;

/**
 * @author dongliang7
 * @projectName websocket-parent
 * @ClassName PushMsgServiceImpl.java
 * @description: 推送消息实现类
 * @createTime 2023年02月06日 16:45:00
 */
@Service
public class PushMsgServiceImpl implements PushMsgService {

    @Override
    public void pushMsgToOne(String userId, String msg) {
        Channel channel = NettyConfig.getChannel(userId);
        if (Objects.isNull(channel)) {
            throw new RuntimeException("未连接socket服务器");
        }

        channel.writeAndFlush(new TextWebSocketFrame(msg));
    }

    @Override
    public void pushMsgToAll(String msg) {
        NettyConfig.getChannelGroup().writeAndFlush(new TextWebSocketFrame(msg));
    }
}

文章值贴出部分关键代码，具体的详情代码参加代码仓库的netty模块

代码仓库

• github.com/Harries/spr...

三、测试

启动springboot工程

2024-03-08 11:21:32.975  INFO 10348 --- [       Thread-2] com.et.netty.server.NettyServer          : Server started and listen on:/0:0:0:0:0:0:0:0:8889

postman创建websocket连接 ws://127.0.0.1:8889/webSocket，并发送消息{'uid':'sss'}给服务端

打开浏览器，给用户sss推送消息 http://127.0.0.1:8088/push/sss

四、引用

• www.cnblogs.com/dongl961230...
• www.liuhaihua.cn/archives/71...