Netty框架实现TCP/IP通信

项目中需要使用到TCP/IP协议完成数据的发送与接收。如果只是用以前写的简单的socket套接字方法，每次接收发送消息都会创建新的socket再关闭socket，造成资源浪费。于是使用netty框架完成java网络通信。
Netty框架的内容很多，这里只是代码展示其中的一个功能。

代码仓库

这里使用的是Springboot+Netty框架，使用maven搭建项目。这里是在一个项目中搭建服务端与客户端，所以端口一样。还可以使用TCP/UTP工具自己搭建服务端和客户端，只要在yml文件中修改ip和端口就好。

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"><modelVersion>4.0.0</modelVersion><groupId>com.hzx.testmaven15netty</groupId><artifactId>testmaven15netty</artifactId><version>1.0-SNAPSHOT</version><parent><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-parent</artifactId><version>2.3.0.RELEASE</version></parent><dependencies><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter</artifactId></dependency><dependency><groupId>io.netty</groupId><artifactId>netty-all</artifactId><version>4.1.31.Final</version></dependency></dependencies></project>

application.yml

server:port: 8080# 作为客户端请求的服务端地址
netty:tcp:server:# 作为客户端请求的服务端地址host: 127.0.0.1# 作为客户端请求的服务端端口port: 7000client:# 作为服务端开放给客户端的端口port: 7000

服务端

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 java.util.Map;
import java.util.concurrent.ConcurrentHashMap;@Component
public class NettyTcpServer {private static final Logger LOGGER = 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handler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2private EventLoopGroup worker = new NioEventLoopGroup();@AutowiredServerChannelInitializer 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ChannelHandlerWorkerGroup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LOGGER.info("Netty tcp server start success,port={}",port);}else {LOGGER.error("Netty tcp server start fail");}return channelFuture1;}/*** 停止Netty tcp server服务*/public void destroy(){if (channel != null) {channel.close();}try {Future<?> future = worker.shutdownGracefully().await();if (!future.isSuccess()) {LOGGER.error("netty tcp workerGroup shutdown fail,{}",future.cause());}} catch (InterruptedException e) {LOGGER.error(e.toString());}LOGGER.info("Netty tcp server shutdown success");}
}

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;@Component
public class ServerChannelInitializer extends ChannelInitializer<SocketChannel> {@AutowiredServerChannelHandler serverChannelHandler;@Overrideprotected 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Handlerpipeline.addLast("serverChannelHandler",serverChannelHandler);}
}

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 org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.stereotype.Component;@Component
@ChannelHandler.Sharable
public class ServerChannelHandler extends SimpleChannelInboundHandler<Object> {private static final Logger LOGGER = LoggerFactory.getLogger(ServerChannelHandler.class);/*** 拿到传过来的msg数据，开始处理* @param channelHandlerContext* @param msg* @throws Exception*/@Overrideprotected void channelRead0(ChannelHandlerContext channelHandlerContext, Object msg) throws Exception {LOGGER.info("Netty tcp server receive message: {}",msg);channelHandlerContext.writeAndFlush(" response message "+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*/@Overridepublic void channelActive(ChannelHandlerContext ctx) throws Exception {super.channelActive(ctx);LOGGER.info("tcp client "+getRemoteAddress(ctx)+" connect success");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*/@Overridepublic void channelInactive(ChannelHandlerContext ctx) throws Exception {// 删除Channel Map中失效的ClientNettyTcpServer.map.remove(getIPString(ctx));ctx.close();}/*** 异常处理* @param ctx* @param cause* @throws Exception*/@Overridepublic void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {super.exceptionCaught(ctx, cause);// 发生异常 关闭连接LOGGER.error("引擎{}的通道发生异常，断开连接",getRemoteAddress(ctx));ctx.close();}/*** 心跳机制 超时处理* @param ctx* @param evt* @throws Exception*/@Overridepublic 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) {LOGGER.info("Client: "+socketString+" READER_IDLE读超时");ctx.disconnect();}else if (event.state()==IdleState.WRITER_IDLE){LOGGER.info("Client: "+socketString+" WRITER_IDLE写超时");ctx.disconnect();}else if (event.state()==IdleState.ALL_IDLE){LOGGER.info("Client: "+socketString+" ALL_IDLE总超时");ctx.disconnect();}}}/*** 获取client对象：ip+port* @param channelHandlerContext* @return*/public String getRemoteAddress(ChannelHandlerContext channelHandlerContext){String socketString = "";socketString = channelHandlerContext.channel().remoteAddress().toString();return socketString;}/*** 获取client的ip* @param channelHandlerContext* @return*/public String getIPString(ChannelHandlerContext channelHandlerContext){String ipString = "";String socketString = channelHandlerContext.channel().remoteAddress().toString();int colonAt = socketString.indexOf(":");ipString = socketString.substring(1,colonAt);return ipString;}
}

客户端

import io.netty.bootstrap.Bootstrap;
import io.netty.channel.Channel;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelOption;
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;import javax.xml.ws.Holder;@Component
public class NettyTcpClient {private static final Logger LOGGER = LoggerFactory.getLogger(NettyTcpClient.class);@Value("${netty.tcp.server.host}")String HOST;@Value("${netty.tcp.server.port}")int PORT;@AutowiredClientChannelInitializer clientChannelInitializer;private Channel channel;/*** 初始化 `Bootstrap` 客户端引导程序* @return*/private final Bootstrap getBootstrap(){Bootstrap bootstrap = new Bootstrap();NioEventLoopGroup group = new NioEventLoopGroup();bootstrap.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 bootstrap;}/***  建立连接，获取连接通道对象*/public void connect(){ChannelFuture channelFuture = getBootstrap().connect(HOST, PORT).syncUninterruptibly();if (channelFuture != null&&channelFuture.isSuccess()) {channel = channelFuture.channel();LOGGER.info("connect tcp server host = {},port = {} success", HOST,PORT);}else {LOGGER.error("connect tcp server host = {},port = {} fail",HOST,PORT);}}/*** 向服务器发送消息*/public void sendMessage(Object msg) throws InterruptedException {if (channel != null) {channel.writeAndFlush(msg).sync();}else {LOGGER.warn("消息发送失败，连接尚未建立");}}
}

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;@Component
public class ClientChannelInitializer extends ChannelInitializer<SocketChannel> {@AutowiredClientChannelHandler clientChannelHandler;@Overrideprotected void initChannel(SocketChannel socketChannel) throws Exception {ChannelPipeline pipeline = socketChannel.pipeline();pipeline.addLast("idleStateHandler",new IdleStateHandler(15,0,0, TimeUnit.MINUTES));pipeline.addLast(new StringDecoder(),new StringEncoder());pipeline.addLast("clientChannelHandler",clientChannelHandler);}
}

import io.netty.channel.ChannelHandler;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.SimpleChannelInboundHandler;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.stereotype.Component;@Component
@ChannelHandler.Sharable
public class ClientChannelHandler extends SimpleChannelInboundHandler<Object> {private static final Logger LOGGER = LoggerFactory.getLogger(ClientChannelHandler.class);@Overrideprotected void channelRead0(ChannelHandlerContext channelHandlerContext, Object msg) throws Exception {LOGGER.info("Netty tcp client receive msg : " + msg);}}

启动类

import com.netty.client.NettyTcpClient;
import com.netty.server.NettyTcpServer;
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 StartApplication implements CommandLineRunner {public static void main(String[] args) throws Exception {SpringApplication.run(StartApplication.class, args);}@AutowiredNettyTcpServer nettyTcpServer;@AutowiredNettyTcpClient nettyTcpClient;/*** Callback used to run the bean.** @param args incoming main method arguments* @throws Exception on error*/@Overridepublic void run(String... args) throws Exception {ChannelFuture start = nettyTcpServer.start();nettyTcpClient.connect();for (int i = 0; i < 10; i++) {nettyTcpClient.sendMessage("hello world "+i);}start.channel().closeFuture().syncUninterruptibly();}
}

使用循环让客户端向服务端发送10条数据

运行结果

在这里插入图片描述

"C:\Program Files\Java\jdk1.8.0_271\bin\java.exe" -XX:TieredStopAtLevel=1 -noverify -Dspring.output.ansi.enabled=always -Dcom.sun.management.jmxremote -Dspring.jmx.enabled=true -Dspring.liveBeansView.mbeanDomain -Dspring.application.admin.enabled=true "-javaagent:D:\IDEA\IntelliJ IDEA 2019.1.1\lib\idea_rt.jar=62789:D:\IDEA\IntelliJ IDEA 2019.1.1\bin" -Dfile.encoding=UTF-8 -classpath "C:\Program Files\Java\jdk1.8.0_271\jre\lib\charsets.jar;C:\Program Files\Java\jdk1.8.0_271\jre\lib\deploy.jar;C:\Program Files\Java\jdk1.8.0_271\jre\lib\ext\access-bridge-64.jar;C:\Program Files\Java\jdk1.8.0_271\jre\lib\ext\cldrdata.jar;C:\Program Files\Java\jdk1.8.0_271\jre\lib\ext\dnsns.jar;C:\Program Files\Java\jdk1.8.0_271\jre\lib\ext\jaccess.jar;C:\Program Files\Java\jdk1.8.0_271\jre\lib\ext\jfxrt.jar;C:\Program Files\Java\jdk1.8.0_271\jre\lib\ext\localedata.jar;C:\Program Files\Java\jdk1.8.0_271\jre\lib\ext\nashorn.jar;C:\Program Files\Java\jdk1.8.0_271\jre\lib\ext\sqljdbc4-4.0.0.jar;C:\Program Files\Java\jdk1.8.0_271\jre\lib\ext\sunec.jar;C:\Program Files\Java\jdk1.8.0_271\jre\lib\ext\sunjce_provider.jar;C:\Program Files\Java\jdk1.8.0_271\jre\lib\ext\sunmscapi.jar;C:\Program Files\Java\jdk1.8.0_271\jre\lib\ext\sunpkcs11.jar;C:\Program Files\Java\jdk1.8.0_271\jre\lib\ext\zipfs.jar;C:\Program Files\Java\jdk1.8.0_271\jre\lib\javaws.jar;C:\Program Files\Java\jdk1.8.0_271\jre\lib\jce.jar;C:\Program Files\Java\jdk1.8.0_271\jre\lib\jfr.jar;C:\Program Files\Java\jdk1.8.0_271\jre\lib\jfxswt.jar;C:\Program Files\Java\jdk1.8.0_271\jre\lib\jsse.jar;C:\Program Files\Java\jdk1.8.0_271\jre\lib\management-agent.jar;C:\Program Files\Java\jdk1.8.0_271\jre\lib\plugin.jar;C:\Program Files\Java\jdk1.8.0_271\jre\lib\resources.jar;C:\Program Files\Java\jdk1.8.0_271\jre\lib\rt.jar;D:\Java Code\testmaven15netty\target\classes;D:\Maven\myreprository\org\springframework\boot\spring-boot-starter\2.3.0.RELEASE\spring-boot-starter-2.3.0.RELEASE.jar;D:\Maven\myreprository\org\springframework\boot\spring-boot\2.3.0.RELEASE\spring-boot-2.3.0.RELEASE.jar;D:\Maven\myreprository\org\springframework\spring-context\5.2.6.RELEASE\spring-context-5.2.6.RELEASE.jar;D:\Maven\myreprository\org\springframework\spring-aop\5.2.6.RELEASE\spring-aop-5.2.6.RELEASE.jar;D:\Maven\myreprository\org\springframework\spring-beans\5.2.6.RELEASE\spring-beans-5.2.6.RELEASE.jar;D:\Maven\myreprository\org\springframework\spring-expression\5.2.6.RELEASE\spring-expression-5.2.6.RELEASE.jar;D:\Maven\myreprository\org\springframework\boot\spring-boot-autoconfigure\2.3.0.RELEASE\spring-boot-autoconfigure-2.3.0.RELEASE.jar;D:\Maven\myreprository\org\springframework\boot\spring-boot-starter-logging\2.3.0.RELEASE\spring-boot-starter-logging-2.3.0.RELEASE.jar;D:\Maven\myreprository\ch\qos\logback\logback-classic\1.2.3\logback-classic-1.2.3.jar;D:\Maven\myreprository\ch\qos\logback\logback-core\1.2.3\logback-core-1.2.3.jar;D:\Maven\myreprository\org\slf4j\slf4j-api\1.7.30\slf4j-api-1.7.30.jar;D:\Maven\myreprository\org\apache\logging\log4j\log4j-to-slf4j\2.13.2\log4j-to-slf4j-2.13.2.jar;D:\Maven\myreprository\org\apache\logging\log4j\log4j-api\2.13.2\log4j-api-2.13.2.jar;D:\Maven\myreprository\org\slf4j\jul-to-slf4j\1.7.30\jul-to-slf4j-1.7.30.jar;D:\Maven\myreprository\jakarta\annotation\jakarta.annotation-api\1.3.5\jakarta.annotation-api-1.3.5.jar;D:\Maven\myreprository\org\springframework\spring-core\5.2.6.RELEASE\spring-core-5.2.6.RELEASE.jar;D:\Maven\myreprository\org\springframework\spring-jcl\5.2.6.RELEASE\spring-jcl-5.2.6.RELEASE.jar;D:\Maven\myreprository\org\yaml\snakeyaml\1.26\snakeyaml-1.26.jar;D:\Maven\myreprository\io\netty\netty-all\4.1.31.Final\netty-all-4.1.31.Final.jar" com.netty.StartApplication.   ____          _            __ _ _/\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \\\/  ___)| |_)| | | | | || (_| |  ) ) ) )'  |____| .__|_| |_|_| |_\__, | / / / /=========|_|==============|___/=/_/_/_/:: Spring Boot ::        (v2.3.0.RELEASE)2021-07-13 08:32:17.161  INFO 18068 --- [           main] com.netty.StartApplication               : Starting StartApplication on LAPTOP-H9JFQJGF with PID 18068 (D:\Java Code\testmaven15netty\target\classes started by huangzixiao in D:\Java Code\testmaven15netty)
2021-07-13 08:32:17.165  INFO 18068 --- [           main] com.netty.StartApplication               : No active profile set, falling back to default profiles: default
2021-07-13 08:32:18.371  INFO 18068 --- [           main] com.netty.StartApplication               : Started StartApplication in 1.706 seconds (JVM running for 2.672)
2021-07-13 08:32:18.931  INFO 18068 --- [           main] com.netty.server.NettyTcpServer          : Netty tcp server start success,port=7000
2021-07-13 08:32:19.016  INFO 18068 --- [           main] com.netty.client.NettyTcpClient          : connect tcp server host = 127.0.0.1,port = 7000 success
2021-07-13 08:32:19.078  INFO 18068 --- [ntLoopGroup-3-1] com.netty.server.ServerChannelHandler    : tcp client /127.0.0.1:52653 connect success
2021-07-13 08:32:19.100  INFO 18068 --- [ntLoopGroup-3-1] com.netty.server.ServerChannelHandler    : Netty tcp server receive message: hello world 0
2021-07-13 08:32:19.100  INFO 18068 --- [ntLoopGroup-3-1] com.netty.server.ServerChannelHandler    : Netty tcp server receive message: hello world 1
2021-07-13 08:32:19.100  INFO 18068 --- [ntLoopGroup-4-1] com.netty.client.ClientChannelHandler    : Netty tcp client receive msg :  response message hello world 0
2021-07-13 08:32:19.100  INFO 18068 --- [ntLoopGroup-3-1] com.netty.server.ServerChannelHandler    : Netty tcp server receive message: hello world 2
2021-07-13 08:32:19.100  INFO 18068 --- [ntLoopGroup-4-1] com.netty.client.ClientChannelHandler    : Netty tcp client receive msg :  response message hello world 1
2021-07-13 08:32:19.100  INFO 18068 --- [ntLoopGroup-3-1] com.netty.server.ServerChannelHandler    : Netty tcp server receive message: hello world 3
2021-07-13 08:32:19.100  INFO 18068 --- [ntLoopGroup-4-1] com.netty.client.ClientChannelHandler    : Netty tcp client receive msg :  response message hello world 2
2021-07-13 08:32:19.100  INFO 18068 --- [ntLoopGroup-3-1] com.netty.server.ServerChannelHandler    : Netty tcp server receive message: hello world 4
2021-07-13 08:32:19.100  INFO 18068 --- [ntLoopGroup-4-1] com.netty.client.ClientChannelHandler    : Netty tcp client receive msg :  response message hello world 3
2021-07-13 08:32:19.104  INFO 18068 --- [ntLoopGroup-3-1] com.netty.server.ServerChannelHandler    : Netty tcp server receive message: hello world 5
2021-07-13 08:32:19.104  INFO 18068 --- [ntLoopGroup-4-1] com.netty.client.ClientChannelHandler    : Netty tcp client receive msg :  response message hello world 4
2021-07-13 08:32:19.104  INFO 18068 --- [ntLoopGroup-3-1] com.netty.server.ServerChannelHandler    : Netty tcp server receive message: hello world 6
2021-07-13 08:32:19.104  INFO 18068 --- [ntLoopGroup-4-1] com.netty.client.ClientChannelHandler    : Netty tcp client receive msg :  response message hello world 5
2021-07-13 08:32:19.104  INFO 18068 --- [ntLoopGroup-3-1] com.netty.server.ServerChannelHandler    : Netty tcp server receive message: hello world 7
2021-07-13 08:32:19.104  INFO 18068 --- [ntLoopGroup-4-1] com.netty.client.ClientChannelHandler    : Netty tcp client receive msg :  response message hello world 6 response message hello world 7
2021-07-13 08:32:19.104  INFO 18068 --- [ntLoopGroup-3-1] com.netty.server.ServerChannelHandler    : Netty tcp server receive message: hello world 8
2021-07-13 08:32:19.104  INFO 18068 --- [ntLoopGroup-4-1] com.netty.client.ClientChannelHandler    : Netty tcp client receive msg :  response message hello world 8
2021-07-13 08:32:19.104  INFO 18068 --- [ntLoopGroup-3-1] com.netty.server.ServerChannelHandler    : Netty tcp server receive message: hello world 9
2021-07-13 08:32:19.104  INFO 18068 --- [ntLoopGroup-4-1] com.netty.client.ClientChannelHandler    : Netty tcp client receive msg :  response message hello world 9