《精通并发与Netty》学习笔记（08 - netty4+springboot项目案例）

时间：2019-05-21 11:34:08 阅读：104 评论：0 收藏：0 [点我收藏+]

本节通过案例介绍springboot与netty的集成

第一步：新建Spring Initializr 项目

技术分享图片

我这里选择Gradle项目，也可选择Maven项目

技术分享图片

（注意：最好选择自己下载gradle,如下图)

技术分享图片

然后修改build.gradle文件，加入依赖(需要安装Lombok插件)

plugins {
    id ‘org.springframework.boot‘ version ‘2.1.5.RELEASE‘
    id ‘java‘
}

apply plugin: ‘io.spring.dependency-management‘

group = ‘com.spring.netty‘
version = ‘0.0.1-SNAPSHOT‘
sourceCompatibility = ‘1.8‘
targetCompatibility = 1.8

repositories {
    mavenCentral()
}

dependencies {
    compile(
            "junit:junit:4.12",
            "io.netty:netty-all:4.1.36.Final",
            "org.springframework.boot:spring-boot-starter",
            "org.springframework.boot:spring-boot-starter-test",

            "org.projectlombok:lombok:1.18.8"

) }

接下来编写服务端程序

package com.spring.netty.springbootnettydemo;

import io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.Channel;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelOption;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.nio.NioServerSocketChannel;
import io.netty.util.concurrent.Future;
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.PreDestroy;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;

/**
 * description:
 * @since 2019/05/21
 **/
@Component
public class NettyTcpServer {

    private static final Logger log = LoggerFactory.getLogger(NettyTcpServer.class);
    //boss事件轮询线程组
    //处理Accept连接事件的线程，这里线程数设置为1即可，netty处理链接事件默认为单线程，过度设置反而浪费cpu资源
    private EventLoopGroup boss = new NioEventLoopGroup(1);
    //worker事件轮询线程组
    //处理hadnler的工作线程，其实也就是处理IO读写 。线程数据默认为 CPU 核心数乘以2
    private EventLoopGroup worker = new NioEventLoopGroup();

    @Autowired
    ServerChannelInitializer serverChannelInitializer;

    @Value("${netty.tcp.client.port}")
    private Integer port;

    //与客户端建立连接后得到的通道对象
    private Channel channel;

    /**
     * 存储client的channel
     * key:ip，value:Channel
     */
    public static Map<String, Channel> map = new ConcurrentHashMap<String, Channel>();

    /**
     * 开启Netty tcp server服务
     *
     * @return
     */
    public ChannelFuture start() {
        //启动类
        ServerBootstrap serverBootstrap = new ServerBootstrap();
        serverBootstrap.group(boss, worker)//组配置，初始化ServerBootstrap的线程组
                .channel(NioServerSocketChannel.class)///构造channel通道工厂//bossGroup的通道，只是负责连接
                .childHandler(serverChannelInitializer)//设置通道处理者ChannelHandler////workerGroup的处理器
                .option(ChannelOption.SO_BACKLOG, 1024)//socket参数，当服务器请求处理程全满时，用于临时存放已完成三次握手请求的队列的最大长度。如果未设置或所设置的值小于1，Java将使用默认值50。
                .childOption(ChannelOption.SO_KEEPALIVE, true);//启用心跳保活机制，tcp，默认2小时发一次心跳
        //Future：异步任务的生命周期，可用来获取任务结果
        ChannelFuture channelFuture1 = serverBootstrap.bind(port).syncUninterruptibly();//绑定端口，开启监听，同步等待
        if (channelFuture1 != null && channelFuture1.isSuccess()) {
            channel = channelFuture1.channel();//获取通道
            log.info("Netty tcp server start success, port = {}", port);
        } else {
            log.error("Netty tcp server start fail");
        }
        return channelFuture1;
    }

    /**
     * 停止Netty tcp server服务
     */
    @PreDestroy
    public void destroy() {
        if (channel != null) {
            channel.close();
        }
        try {
            Future<?> future = worker.shutdownGracefully().await();
            if (!future.isSuccess()) {
                log.error("netty tcp workerGroup shutdown fail, {}", future.cause());
            }
            Future<?> future1 = boss.shutdownGracefully().await();
            if (!future1.isSuccess()) {
                log.error("netty tcp bossGroup shutdown fail, {}", future1.cause());
            }
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        log.info("Netty tcp server shutdown success");
    }

}

package com.spring.netty.springbootnettydemo;

import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelPipeline;
import io.netty.channel.socket.SocketChannel;
import io.netty.handler.codec.string.StringDecoder;
import io.netty.handler.codec.string.StringEncoder;
import io.netty.handler.timeout.IdleStateHandler;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;

import java.util.concurrent.TimeUnit;

/**
 * description: 通道初始化，主要用于设置各种Handler
 * @since 2019/05/21
 **/
@Component
public class ServerChannelInitializer extends ChannelInitializer<SocketChannel> {

    @Autowired
    ServerChannelHandler serverChannelHandler;

    @Override
    protected void initChannel(SocketChannel socketChannel) throws Exception {
        ChannelPipeline pipeline = socketChannel.pipeline();
        //IdleStateHandler心跳机制,如果超时触发Handle中userEventTrigger()方法
        pipeline.addLast("idleStateHandler",
                new IdleStateHandler(15, 0, 0, TimeUnit.MINUTES));
        //字符串编解码器
        pipeline.addLast(
                new StringDecoder(),
                new StringEncoder()
        );
        //自定义Handler
        pipeline.addLast("serverChannelHandler", serverChannelHandler);
    }
}

package com.spring.netty.springbootnettydemo;

import io.netty.channel.ChannelHandler;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.SimpleChannelInboundHandler;
import io.netty.handler.timeout.IdleState;
import io.netty.handler.timeout.IdleStateEvent;
import lombok.extern.slf4j.Slf4j;
import org.springframework.stereotype.Component;

/**
 * description:
 * @since 2019/05/21
 **/
@Component
@ChannelHandler.Sharable
@Slf4j
public class ServerChannelHandler extends SimpleChannelInboundHandler<Object> {

    /**
     * 拿到传过来的msg数据，开始处理
     *
     * @param ctx
     * @param msg
     * @throws Exception
     */
    @Override
    protected void channelRead0(ChannelHandlerContext ctx, Object msg) throws Exception {
        System.out.println("Netty tcp server receive msg : " + msg);
        ctx.channel().writeAndFlush(" response msg ").syncUninterruptibly();
    }

    /**
     * 活跃的、有效的通道
     * 第一次连接成功后进入的方法
     *
     * @param ctx
     * @throws Exception
     */
    @Override
    public void channelActive(ChannelHandlerContext ctx) throws Exception {
        super.channelActive(ctx);
        log.info("tcp client " + getRemoteAddress(ctx) + " connect success");
        //往channel map中添加channel信息
        NettyTcpServer.map.put(getIPString(ctx), ctx.channel());
    }

    /**
     * 不活动的通道
     * 连接丢失后执行的方法（client端可据此实现断线重连）
     *
     * @param ctx
     * @throws Exception
     */
    @Override
    public void channelInactive(ChannelHandlerContext ctx) throws Exception {
        //删除Channel Map中的失效Client
        NettyTcpServer.map.remove(getIPString(ctx));
        ctx.close();
    }

    /**
     * 异常处理
     *
     * @param ctx
     * @param cause
     * @throws Exception
     */
    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
        super.exceptionCaught(ctx, cause);
        //发生异常，关闭连接
        log.error("引擎 {} 的通道发生异常，即将断开连接", getRemoteAddress(ctx));
        ctx.close();//再次建议close
    }

    /**
     * 心跳机制，超时处理
     *
     * @param ctx
     * @param evt
     * @throws Exception
     */
    @Override
    public void userEventTriggered(ChannelHandlerContext ctx, Object evt) throws Exception {
        String socketString = ctx.channel().remoteAddress().toString();
        if (evt instanceof IdleStateEvent) {
            IdleStateEvent event = (IdleStateEvent) evt;
            if (event.state() == IdleState.READER_IDLE) {
                log.info("Client: " + socketString + " READER_IDLE 读超时");
                ctx.disconnect();//断开
            } else if (event.state() == IdleState.WRITER_IDLE) {
                log.info("Client: " + socketString + " WRITER_IDLE 写超时");
                ctx.disconnect();
            } else if (event.state() == IdleState.ALL_IDLE) {
                log.info("Client: " + socketString + " ALL_IDLE 总超时");
                ctx.disconnect();
            }
        }
    }

    /**
     * 获取client对象：ip+port
     *
     * @param ctx
     * @return
     */
    public String getRemoteAddress(ChannelHandlerContext ctx) {
        String socketString = "";
        socketString = ctx.channel().remoteAddress().toString();
        return socketString;
    }

    /**
     * 获取client的ip
     *
     * @param ctx
     * @return
     */
    public String getIPString(ChannelHandlerContext ctx) {
        String ipString = "";
        String socketString = ctx.channel().remoteAddress().toString();
        int colonAt = socketString.indexOf(":");
        ipString = socketString.substring(1, colonAt);
        return ipString;
    }

}

编写客户端代码

package com.spring.netty.springbootnettydemo;

import io.netty.bootstrap.Bootstrap;
import io.netty.channel.Channel;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelOption;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.nio.NioSocketChannel;
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;

/**
 * description:
 * @since 2019/05/21
 **/
@Component
public class NettyTcpClient {

    private static final Logger log = LoggerFactory.getLogger(NettyTcpClient.class);

    @Value(("${netty.tcp.server.host}"))
    String HOST;
    @Value("${netty.tcp.server.port}")
    int PORT;

    @Autowired
    ClientChannelInitializer clientChannelInitializer;

    //与服务端建立连接后得到的通道对象
    private Channel channel;

    /**
     * 初始化 `Bootstrap` 客户端引导程序
     *
     * @return
     */
    private final Bootstrap getBootstrap() {
        Bootstrap b = new Bootstrap();
        EventLoopGroup group = new NioEventLoopGroup();
        b.group(group)
                .channel(NioSocketChannel.class)//通道连接者
                .handler(clientChannelInitializer)//通道处理者
                .option(ChannelOption.SO_KEEPALIVE, true);//心跳报活
        return b;
    }

    /**
     * 建立连接，获取连接通道对象
     *
     * @return
     */
    public void connect() {
        ChannelFuture channelFuture = getBootstrap().connect(HOST, PORT).syncUninterruptibly();
        if (channelFuture != null && channelFuture.isSuccess()) {
            channel = channelFuture.channel();
            log.info("connect tcp server host = {}, port = {} success", HOST, PORT);
        } else {
            log.error("connect tcp server host = {}, port = {} fail", HOST, PORT);
        }
    }

    /**
     * 向服务器发送消息
     *
     * @param msg
     * @throws Exception
     */
    public void sendMsg(Object msg) throws Exception {
        if (channel != null) {
            channel.writeAndFlush(msg).sync();
        } else {
            log.warn("消息发送失败,连接尚未建立!");
        }
    }

}

package com.spring.netty.springbootnettydemo;

import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelPipeline;
import io.netty.channel.socket.SocketChannel;
import io.netty.handler.codec.string.StringDecoder;
import io.netty.handler.codec.string.StringEncoder;
import io.netty.handler.timeout.IdleStateHandler;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;

import java.util.concurrent.TimeUnit;

/**
 * description: 通道初始化，主要用于设置各种Handler
 * @since 2019/05/21
 **/
@Component
public class ClientChannelInitializer extends ChannelInitializer<SocketChannel> {

    @Autowired
    ClientChannelHandler clientChannelHandler;

    @Override
    protected void initChannel(SocketChannel socketChannel) throws Exception {
        ChannelPipeline pipeline = socketChannel.pipeline();
        //IdleStateHandler心跳机制,如果超时触发Handle中userEventTrigger()方法
        pipeline.addLast("idleStateHandler",
                new IdleStateHandler(15, 0, 0, TimeUnit.MINUTES));
        //字符串编解码器
        pipeline.addLast(
                new StringDecoder(),
                new StringEncoder()
        );
        //自定义Handler
        pipeline.addLast("clientChannelHandler", clientChannelHandler);
    }
}

package com.spring.netty.springbootnettydemo;

import io.netty.channel.ChannelHandler;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.SimpleChannelInboundHandler;
import org.springframework.stereotype.Component;

/**
 * description:
 * @since 2019/05/21
 **/
@Component
@ChannelHandler.Sharable
public class ClientChannelHandler extends SimpleChannelInboundHandler<Object> {

    /**
     * 从服务器接收到的msg
     *
     * @param ctx
     * @param msg
     * @throws Exception
     */
    @Override
    protected void channelRead0(ChannelHandlerContext ctx, Object msg) throws Exception {
        System.out.println("Netty tcp client receive msg : " + msg);
    }

}

最后修改springboot启动程序

package com.spring.netty.springbootnettydemo;

import io.netty.channel.ChannelFuture;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.CommandLineRunner;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class SpringbootNettyDemoApplication implements CommandLineRunner {

    public static void main(String[] args) {
        SpringApplication.run(SpringbootNettyDemoApplication.class, args);
    }

    @Autowired
    NettyTcpServer nettyTcpServer;
    @Autowired
    NettyTcpClient nettyTcpClient;

    @Override
    public void run(String... args) throws Exception {
        //启动服务端
        ChannelFuture start = nettyTcpServer.start();

        //启动客户端，发送数据
        nettyTcpClient.connect();
        for (int i = 0; i < 10; i++) {
            nettyTcpClient.sendMsg("hello world" + i);
        }

        //服务端管道关闭的监听器并同步阻塞,直到channel关闭,线程才会往下执行,结束进程
        start.channel().closeFuture().syncUninterruptibly();
    }

}

运行测试效果如下：

技术分享图片

本节我们通过一个案例将springboot与netty结合实现了异步通信，下节我们一起来研究下Google的gRPC

《精通并发与Netty》学习笔记（08 - netty4+springboot项目案例）

原文：https://www.cnblogs.com/happy2010/p/10895209.html

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