springboot整合netty的多种方式

　　netty作为一个高性能的io框架，是非好用的一个技术框架，

　　Netty 是一个基于NIO的客户、服务器端编程框架，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

　　那么如何和springboot这个比较流行的框架进行整合呢？

　　首先整个项目引入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类是不会改变的

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);
    }

    @Override
    public void channelReadComplete(ChannelHandlerContext ctx){
        ctx.writeAndFlush(ChannelFutureListener.CLOSE);
    }

    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause){
        cause.printStackTrace();
        ctx.close();
    }

}

这个handler是我从官网上copy下来的

方式一：注解@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");
        }

    }

}

点击启动：

看日志：

说明已经启动

那么这个注解为什么这么神奇呢：

大概的意思，大家看下，意思就是这个方法会随着类的加载而加载，初始化加载的意思：

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

方式二：利用监听器启动：

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) {

    }

}

启动类：

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);
    }

}

看日志：

三 ：利用 ApplicationListener  上下文监听器

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();
        }
    }

}

启动类：

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);
    }

}

看启动日志：

四：commiandLinerunner启动

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();
    }
}

看日志：

代表这四种都可以启动成功，下章接再分析后面三种为什么可以启动成功