Springboot access to netty to achieve online statistics on the number of people

Netty YesA asynchronous event-driven web application framework, for rapid development of maintainable high-performance protocol servers and clients. Netty is a NIO client server framework that quickly and easily develops web applications such as protocol servers and clients. It greatly simplifies and streamlines network programming, such as TCP and UDP socket servers.

“Quick and easy” does not mean that the generated applications are affected by maintainability or performance issues. Netty is carefully designed and draws on implementation experiences from many protocols such as FTP, SMTP, HTTP, and various binary and text-based legacy protocols. As a result, Netty successfully found a way to achieve ease of development, performance, stability, and flexibility without compromise.

To connect to Netty in Spring Boot and implement the function of counting people online, you can follow the following steps:

Add dependencies: inAdd Netty's related dependencies to the file. You can choose the appropriate version as needed, for example:

<dependency>
    <groupId></groupId>
    <artifactId>netty-all</artifactId>
    <version>4.1.</version>
</dependency>

Create a Netty Server: Create a class to start and configure a Netty server, for exampleNettyServer。

import ;
import ;
import ;
import ;
import ;
import ;
import ;

public class NettyServer {

    private final int port;
    
    public NettyServer(int port) {
         = port;
    }
    
    public void run() throws Exception {
        EventLoopGroup bossGroup = new NioEventLoopGroup();
        EventLoopGroup workerGroup = new NioEventLoopGroup();
        
        try {
            ServerBootstrap b = new ServerBootstrap();
            (bossGroup, workerGroup)
                .channel()
                .childHandler(new ChannelInitializer&lt;SocketChannel&gt;() {
                    @Override
                    protected void initChannel(SocketChannel ch) throws Exception {
                        ().addLast(new YourChannelHandler());
                    }
                });

            ChannelFuture f = (port).sync();
            ().closeFuture().sync();
        } finally {
            ();
            ();
        }
    }

    public static void main(String[] args) throws Exception {
        int port = 8888; // Configure the server port number        new NettyServer(port).run(); // Start the server    }
}

Implement a custom ChannelHandler: You need to write an inherited fromSimpleChannelInboundHandlerCustom ChannelHandler for processing received data.

import ;
import ;

public class YourChannelHandler extends SimpleChannelInboundHandler&lt;String&gt; {
    
    // Maintain variables of online users    private static AtomicInteger onlineCount = new AtomicInteger(0);
    
    @Override
    public void channelActive(ChannelHandlerContext ctx) throws Exception {
        (); // New connections are launched to increase the number of online users    }
    
    @Override
    public void channelInactive(ChannelHandlerContext ctx) throws Exception {
        (); // Connect to offline to reduce the number of online users    }

    @Override
    protected void channelRead0(ChannelHandlerContext ctx, String msg) throws Exception {
        // Process the received message        // ...
    }
}

existYourChannelHandler, by usingAtomicIntegerVariables to maintain the number of people online and inchannelActive()andchannelInactive()In the method, the number of people online is updated when a new connection is established and the connection is disconnected.

Start the Netty Server in Spring Boot: In the entry class of the Spring Boot application, add the code to start the Netty Server.

import ;
import ;

@SpringBootApplication
public class YourApplication {

    public static void main(String[] args) throws Exception {
        int nettyPort = 8888; // Configure Netty server port number        new NettyServer(nettyPort).run(); // Start Netty server        
        (, args); // Start Spring Boot app    }
}

Number of people online in Spring Boot: You can use the number of people online in other components of Spring Boot. For example, you can create a RESTful interface to get the number of people online.

import ;
import ;

@RestController
public class OnlineUserController {
    
    @GetMapping("/online-count")
    public int getOnlineCount() {
        return (); // Get the number of online users    }
}

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