Spring boot intergratd netty implements websocket communication

一、netty introduction

Netty is a java open source framework provided by JBOSS and is now an independent project on Github. Netty provides an asynchronous, event-driven network application framework and tools to quickly develop high-performance, high-reliability network server and client programs. In other words, Netty is a client-side and server-side programming framework based on NIO. Using Netty can ensure that you can quickly and easily develop a network application, such as a client-side or server-side application that implements a certain protocol. Netty is equivalent to simplifying and streamlining the programming and development process of network applications, such as: socket service development based on TCP and UDP. “Fast” and “simple” do not cause maintenance or performance problems. Netty is a project that absorbs the implementation experience of multiple protocols (including FTP, SMTP, HTTP and other binary text protocols) and is quite carefully designed. .In the end, Netty successfully found a way to ensure easy development while also ensuring the performance, stability and scalability of its applications.

二、Code project

Experimental goal: push messages to specified users

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>

Application.yaml

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 2023/02/06日 16:41:00
 */
@Component
public class NettyServer {
    static final Logger log = LoggerFactory.getLogger(NettyServer.class);
    /**
     *netty server port
     */
    @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();
            bootstrap.group(bossGroup, workGroup);
            bootstrap.channel(NioServerSocketChannel.class);
            bootstrap.localAddress(new InetSocketAddress(port));
            bootstrap.childHandler(nettyInitializer);
            ChannelFuture channelFuture = null;
            try {
                channelFuture = bootstrap.bind().sync();
                log.info("Server started and listen on:{}", channelFuture.channel().localAddress());
                channelFuture.channel().closeFuture().sync();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }).start();
    }
   
    @PreDestroy
    public void destroy() throws InterruptedException {
        if (bossGroup != null) {
            bossGroup.shutdownGracefully().sync();
        }
        if (workGroup != null) {
            workGroup.shutdownGracefully().sync();
        }
    }
}

ProjectInitializer

Initialize, set 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: pipeline configutation
 * @createTime 2023/02/06 16:43:00
 */
@Component
public class ProjectInitializer extends ChannelInitializer<SocketChannel> {
    /**
     * webSocket protocol
     */
    static final String WEBSOCKET_PROTOCOL = "WebSocket";
    /**
     * webSocket path
     */
    @Value("${webSocket.netty.path:/webSocket}")
    String webSocketPath;
    @Autowired
    WebSocketHandler webSocketHandler;
    @Override
    protected void initChannel(SocketChannel socketChannel) throws Exception {
        ChannelPipeline pipeline = socketChannel.pipeline();
        pipeline.addLast(new HttpServerCodec());
        pipeline.addLast(new ObjectEncoder());
        pipeline.addLast(new ChunkedWriteHandler());
        pipeline.addLast(new HttpObjectAggregator(8192));
        pipeline.addLast(new WebSocketServerProtocolHandler(webSocketPath, WEBSOCKET_PROTOCOL, true, 65536 * 10));
        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 2023/02/06日 16:44:00
 */
@Component
@ChannelHandler.Sharable
public class WebSocketHandler extends SimpleChannelInboundHandler<TextWebSocketFrame> {
    private static final Logger log = LoggerFactory.getLogger(NettyServer.class);
   
    @Override
    public void handlerAdded(ChannelHandlerContext ctx) throws Exception {
        log.info("new connect：[{}]", ctx.channel().id().asLongText());
        NettyConfig.getChannelGroup().add(ctx.channel());
    }
    /**
     * read
     */
    @Override
    protected void channelRead0(ChannelHandlerContext ctx, TextWebSocketFrame msg) throws Exception {
        log.info("receive  msg：{}", msg.text());
        JSONObject jsonObject = JSONUtil.parseObj(msg.text());
        String uid = jsonObject.getStr("uid");
        NettyConfig.getChannelMap().put(uid, ctx.channel());
        AttributeKey<String> key = AttributeKey.valueOf("userId");
        ctx.channel().attr(key).setIfAbsent(uid);
        ctx.channel().writeAndFlush(new TextWebSocketFrame("server receive msg"));
    }
    @Override
    public void handlerRemoved(ChannelHandlerContext ctx) throws Exception {
        log.info("user disonline :{}", ctx.channel().id().asLongText());
        NettyConfig.getChannelGroup().remove(ctx.channel());
        removeUserId(ctx);
    }
    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
        log.info("error：{}", cause.getMessage());
        NettyConfig.getChannelGroup().remove(ctx.channel());
        removeUserId(ctx);
        ctx.close();
    }
    /**
     * delete the relation that use and channel
     */
    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: config
 */
public class NettyConfig {
   
    private static volatile ChannelGroup channelGroup = null;
   
    private static volatile ConcurrentHashMap<String, Channel> channelMap = null;
    /
    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;
    
    @GetMapping("/{uid}")
    public void pushOne(@PathVariable String uid) {
        pushMsgService.pushMsgToOne(uid, "hello-------------------------");
    }
    
    @GetMapping("/pushAll")
    public void pushAll() {
        pushMsgService.pushMsgToAll("hello all-------------------------");
    }
}

PushMsgService

package com.et.netty.service;
/**
 * @author dongliang7
 * @projectName websocket-parent
 * @ClassName PushMsgService.java
 */
public interface PushMsgService {
    /**
     * push message to Specify user
     */
    void pushMsgToOne(String userId, String msg);
    /**
     * push msg all user
     */
    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;

@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("connection is not open");
        }
        channel.writeAndFlush(new TextWebSocketFrame(msg));
    }
    @Override
    public void pushMsgToAll(String msg) {
        NettyConfig.getChannelGroup().writeAndFlush(new TextWebSocketFrame(msg));
    }
}

The article is worth posting some key codes. The specific detailed codes can be found in the netty module of the code repository.

Code repository

• https://github.com/Harries/springboot-demo

三、Test

start the spring boot application

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

open postman and create websocket connection, then input ws://127.0.0.1:8889/webSocket,click the connect button

send message to netty message

{‘uid’:’sss’}

open your Browser，send messages to user(sss) http://127.0.0.1:8088/push/sss

四、reference

• https://www.cnblogs.com/dongl961230/p/17099057.html
• http://www.liuhaihua.cn/archives/710299.html