What are the ways for springboot to integrate the netty framework?

Netty is a high-performance io framework and a very easy-to-use technical framework.

Netty is a client 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 or server 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 create maintenance or performance problems. Netty is a project that absorbs the implementation experience of multiple protocols (including various binary text protocols such as FTP, SMTP, HTTP, etc.) 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 application.
First of all, introducing the pom

<?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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.2.1.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.cxy</groupId>
    <artifactId>netty</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>netty</name>
    <description>Demo project for Spring Boot</description>

    <properties>
        <java.version>1.8</java.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>io.netty</groupId>
            <artifactId>netty-all</artifactId>
            <version>4.1.25.Final</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
            <exclusions>
                <exclusion>
                    <groupId>org.junit.vintage</groupId>
                    <artifactId>junit-vintage-engine</artifactId>
                </exclusion>
            </exclusions>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

</project>

handler class into the entire project will not The changed

package com.cxy.netty.controller;
import io.netty.buffer.ByteBuf;
import io.netty.channel.ChannelFutureListener;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandlerAdapter;
import io.netty.util.CharsetUtil;
public class EchoServerHandler extends ChannelInboundHandlerAdapter {
    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg){
        ByteBuf in = (ByteBuf) msg;
        System.out.println("Server received: " + in.toString(CharsetUtil.UTF_8));
        ctx.write(in);
    }
    public void channelReadComplete(ChannelHandlerContext ctx){
        ctx.writeAndFlush(ChannelFutureListener.CLOSE);
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause){
        cause.printStackTrace();
        ctx.close();
}

This handler was copied from the official website

Method 1: Annotate @PostConstruct

package com.cxy.netty.controller;
import io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioServerSocketChannel;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.boot.autoconfigure.web.ServerProperties;
import org.springframework.stereotype.Component;
import javax.annotation.PostConstruct;
import javax.annotation.PreDestroy;
import java.net.InetSocketAddress;
@Component
public class NettyServer {
    /*private  int port =8080;
    public int getPort() {
        return port;
    }
    public void setPort(int port) {
        this.port = port;
    }
    public NettyServer(int port) {
        this.port = port;
    }*/
    @PostConstruct
    public void start() throws Exception {
        System.out.println("启动记载netty");
        EventLoopGroup boss = new NioEventLoopGroup();
        EventLoopGroup work = new NioEventLoopGroup();
        ServerBootstrap b = new ServerBootstrap();
        b.group(boss,work)
                .channel(NioServerSocketChannel.class)
                .localAddress(new InetSocketAddress(8082))
                .childHandler(new ChannelInitializer<SocketChannel>() {
                    @Override
                    protected void initChannel(SocketChannel ch) throws Exception {
                        ch.pipeline().addLast(new EchoServerHandler());
                    }
                });
        System.out.println("启动加载netty2");
        ChannelFuture channelFuturef = b.bind().sync();
        if (channelFuturef.isSuccess()){
        System.out.println("启动成功");
        }
    }
}

Click to start:

View the log:

Indicates that it has been started

So why is this annotation so magical:

About the meaning , let’s take a look, it means that this method will be loaded as the class is loaded. The meaning of initial loading is:

@Documented
@Retention (RUNTIME)
@Target(METHOD)
public @interface PostConstruct {
}

Method 2: Use the listener to start:

package com.cxy.netty.controller;
import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;
/**
 * 系统初始化监听器
 * @author Administrator
 *
 */
public class InitListener implements ServletContextListener {
    @Override
    public void contextInitialized(ServletContextEvent sce) {
        
        NettyServer nettyServer = new NettyServer(8081);
        try {
            nettyServer.start();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
    
    @Override
    public void contextDestroyed(ServletContextEvent sce) {
        
    }
}

Start the class:

package com.cxy.netty;
import com.cxy.netty.controller.InitListener;
import com.cxy.netty.controller.NettyServer;
import org.springframework.boot.CommandLineRunner;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.web.servlet.ServletListenerRegistrationBean;
import org.springframework.context.annotation.Bean;
@SpringBootApplication
public class NettyApplication {
    /**
     * 注册监听器
     * @return
     */
    @SuppressWarnings({ "rawtypes", "unchecked" })
    @Bean
    public ServletListenerRegistrationBean servletListenerRegistrationBean() {
        ServletListenerRegistrationBean servletListenerRegistrationBean =
                new ServletListenerRegistrationBean();
        servletListenerRegistrationBean.setListener(new InitListener());
        return servletListenerRegistrationBean;
    }
    public static void main(String[] args) {
        SpringApplication.run(NettyApplication.class, args);
    }
}

Look at the log:

##Method 3: Use the ApplicationListener context listener

package com.cxy.netty.controller;
import com.cxy.netty.controller.NettyServer;
import org.springframework.context.ApplicationListener;
import org.springframework.context.event.ContextRefreshedEvent;
import org.springframework.stereotype.Component;
@Component
public class NettyBooter implements ApplicationListener<ContextRefreshedEvent> {
    @Override
    public void onApplicationEvent(ContextRefreshedEvent event) {
        NettyServer nettyServer = new NettyServer(8081);
        try {
            nettyServer.start();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

Startup class:

package com.cxy.netty;
import com.cxy.netty.controller.NettyServer;
import org.springframework.boot.CommandLineRunner;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.web.servlet.ServletListenerRegistrationBean;
import org.springframework.context.annotation.Bean;
@SpringBootApplication
public class NettyApplication {
   /**
     * 注册监听器
     * @return
     */
   /* @SuppressWarnings({ "rawtypes", "unchecked" })
    @Bean
    public ServletListenerRegistrationBean servletListenerRegistrationBean() {
        ServletListenerRegistrationBean servletListenerRegistrationBean =
                new ServletListenerRegistrationBean();
        servletListenerRegistrationBean.setListener(new InitListener());
        return servletListenerRegistrationBean;
    }*/
    public static void main(String[] args) {
        SpringApplication.run(NettyApplication.class, args);
    }
}

Look at the startup Log:

Method 4: commiandLinerunner starts

package com.cxy.netty;
import com.cxy.netty.controller.NettyServer;
import org.springframework.boot.CommandLineRunner;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.web.servlet.ServletListenerRegistrationBean;
import org.springframework.context.annotation.Bean;
/*
@SpringBootApplication
public class NettyApplication {
   */
/**
     * 注册监听器
     * @return
     *//*
   */
/* @SuppressWarnings({ "rawtypes", "unchecked" })
    @Bean
    public ServletListenerRegistrationBean servletListenerRegistrationBean() {
        ServletListenerRegistrationBean servletListenerRegistrationBean =
                new ServletListenerRegistrationBean();
        servletListenerRegistrationBean.setListener(new InitListener());
        return servletListenerRegistrationBean;
    }*//*
    public static void main(String[] args) {
        SpringApplication.run(NettyApplication.class, args);
    }
}
*/
@SpringBootApplication
public class NettyApplication implements CommandLineRunner {
    public static void main(String[] args) {
        SpringApplication.run(NettyApplication.class, args);
    }
    @Override
    public void run(String... args) throws Exception {
        NettyServer echoServer = new NettyServer(8083);
        echoServer.start();
    }
}

Look at the log:

##

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