使用netty实现im聊天

简书地址图文更清晰： https://www.jianshu.com/p/f455814f3c40

1、新建maven工程
2、引入maven依赖

<dependencies>
        <dependency> <groupId>io.netty</groupId> <artifactId>netty-all</artifactId> <version>4.1.49.Final</version> </dependency> <dependency> <groupId>com.alibaba</groupId> <artifactId>fastjson</artifactId> <version>1.2.68</version> </dependency> </dependencies> <build> <plugins> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-compiler-plugin</artifactId> <version>3.6.1</version> <configuration> <source>1.8</source> <target>1.8</target> </configuration> </plugin> </plugins> </build> 

3、定义消息体MsgBody

public class MsgBody {


    //发送人名称 private String sendUserName; private String msg; public String getSendUserName() { return sendUserName; } public void setSendUserName(String sendUserName) { this.sendUserName = sendUserName; } public String getMsg() { return msg; } public void setMsg(String msg) { this.msg = msg; } } 

4、新建服务器端的NettyServer和ServerHandler

/**
 * netty的服务器
 * @Author: yeyongjian
 * @Date: 2020-05-03 23:34
 */
public class NettyServer { private int port; public NettyServer(int port) { this.port = port; bind(); } private void bind() { EventLoopGroup boss = new NioEventLoopGroup(); EventLoopGroup worker = new NioEventLoopGroup(); try { ServerBootstrap bootstrap = new ServerBootstrap(); bootstrap.group(boss, worker); bootstrap.channel(NioServerSocketChannel.class); bootstrap.option(ChannelOption.SO_BACKLOG, 1024); // 连接数 bootstrap.option(ChannelOption.TCP_NODELAY, true); // 不延迟，消息立即发送 bootstrap.childOption(ChannelOption.SO_KEEPALIVE, true); // 长连接 bootstrap.childHandler(new ChannelInitializer<SocketChannel>() { @Override protected void initChannel(SocketChannel socketChannel){ ChannelPipeline p = socketChannel.pipeline(); ServerHandler serverHandler = new ServerHandler(); p.addLast(serverHandler);// 添加NettyServerHandler，用来处理Server端接收和处理消息的逻辑 } }); ChannelFuture channelFuture = bootstrap.bind(port).sync(); if (channelFuture.isSuccess()) { System.err.println("启动Netty服务成功，端口号：" + this.port); } // 关闭连接 channelFuture.channel().closeFuture().sync(); } catch (Exception e) { System.err.println("启动Netty服务异常，异常信息：" + e.getMessage()); e.printStackTrace(); } finally { boss.shutdownGracefully(); worker.shutdownGracefully(); } } public static void main(String[] args) throws InterruptedException { new NettyServer(10086); } } 

import com.alibaba.fastjson.JSONObject; import com.eujian.im.MsgBody; import io.netty.buffer.ByteBuf; import io.netty.buffer.Unpooled; import io.netty.channel.Channel; import io.netty.channel.ChannelHandlerContext; import io.netty.channel.ChannelId; import io.netty.channel.SimpleChannelInboundHandler; import java.io.UnsupportedEncodingException; import java.util.HashMap; import java.util.Map; /** * 服务器的处理器 * @Author: yeyongjian * @Date: 2020-05-03 23:35 */ public class ServerHandler extends SimpleChannelInboundHandler { //连接id与容器的关系 private static Map<String, ChannelHandlerContext> map = new HashMap<>(); @Override protected void channelRead0(ChannelHandlerContext ctx, Object msg) { Channel channel = ctx.channel(); ChannelId id = channel.id(); map.put(id.toString(),ctx); ByteBuf buf = (ByteBuf) msg; String recieved = getMessage(buf); MsgBody msgBody = JSONObject.parseObject(recieved, MsgBody.class); String format = String.format("服务器接收到客户端消息，发送人：%s，发送信息：%s", msgBody.getSendUserName(), msgBody.getMsg()); System.err.println(format); map.forEach((k,v)->{ try { if(id.toString().equals(k)){ return; } MsgBody sendMsgBody = new MsgBody(); sendMsgBody.setSendUserName(msgBody.getSendUserName()); sendMsgBody.setMsg(msgBody.getMsg()); v.writeAndFlush(getSendByteBuf(JSONObject.toJSONString(sendMsgBody))); System.err.println("服务器回复消息："+JSONObject.toJSONString(sendMsgBody)); } catch (UnsupportedEncodingException e) { e.printStackTrace(); } }); } /* * 从ByteBuf中获取信息 使用UTF-8编码返回 */ private String getMessage(ByteBuf buf) { byte[] con = new byte[buf.readableBytes()]; buf.readBytes(con); try { return new String(con, "UTF8"); } catch (UnsupportedEncodingException e) { e.printStackTrace(); return null; } } private ByteBuf getSendByteBuf(String message) throws UnsupportedEncodingException { byte[] req = message.getBytes("UTF-8"); ByteBuf pingMessage = Unpooled.buffer(); pingMessage.writeBytes(req); return pingMessage; } } 

5、新建客户端代码

import com.alibaba.fastjson.JSONObject; import com.eujian.im.MsgBody; import io.netty.buffer.ByteBuf; import io.netty.buffer.Unpooled; import io.netty.channel.ChannelHandlerContext; import io.netty.channel.SimpleChannelInboundHandler; import java.io.UnsupportedEncodingException; public class NettyClientHandler extends SimpleChannelInboundHandler { private ByteBuf firstMessage; private ChannelHandlerContext ctx; private String userName; public String getUserName() { return userName; } public void setUserName(String userName) { this.userName = userName; } public void sendMsg(String str){ byte[] data = str.getBytes(); firstMessage = Unpooled.buffer(); firstMessage.writeBytes(data); ctx.writeAndFlush(firstMessage); } @Override public void channelActive(ChannelHandlerContext ctx) { this.ctx= ctx; MsgBody msgBody = new MsgBody(); msgBody.setSendUserName(userName); msgBody.setMsg("进入聊天室"); byte[] data = JSONObject.toJSONString(msgBody).getBytes(); firstMessage = Unpooled.buffer(); firstMessage.writeBytes(data); ctx.writeAndFlush(firstMessage); } @Override protected void channelRead0(ChannelHandlerContext channelHandlerContext, Object msg){ ByteBuf buf = (ByteBuf) msg; String rev = getMessage(buf); MsgBody msgBody = JSONObject.parseObject(rev, MsgBody.class); String format = String.format("客户端收到服务器消息，发送人：%s，发送信息：%s", msgBody.getSendUserName(), msgBody.getMsg()); System.err.println(format); } private String getMessage(ByteBuf buf) { byte[] con = new byte[buf.readableBytes()]; buf.readBytes(con); try { return new String(con, "UTF8"); } catch (UnsupportedEncodingException e) { e.printStackTrace(); return null; } } } 

import com.alibaba.fastjson.JSONObject; import com.eujian.im.MsgBody; import io.netty.bootstrap.Bootstrap; import io.netty.channel.ChannelFuture; import io.netty.channel.ChannelInitializer; import io.netty.channel.ChannelOption; import io.netty.channel.EventLoopGroup; import io.netty.channel.nio.NioEventLoopGroup; import io.netty.channel.socket.SocketChannel; import io.netty.channel.socket.nio.NioSocketChannel; import java.util.Scanner; public class NettyClient { public NettyClientHandler nettyClientHandler; /* * 服务器端口号 */ private int port; private String sendUserName; /* * 服务器IP */ private String host; public NettyClient(int port, String host, String sendUserName) throws InterruptedException { this.port = port; this.host = host; this.sendUserName = sendUserName; start(); } private void start() throws InterruptedException { EventLoopGroup eventLoopGroup = new NioEventLoopGroup(); try { Bootstrap bootstrap = new Bootstrap(); bootstrap.channel(NioSocketChannel.class); bootstrap.option(ChannelOption.SO_KEEPALIVE, true); bootstrap.group(eventLoopGroup); bootstrap.remoteAddress(host, port); bootstrap.handler(new ChannelInitializer<SocketChannel>() { @Override protected void initChannel(SocketChannel socketChannel) throws Exception { nettyClientHandler = new NettyClientHandler(); nettyClientHandler.setUserName(sendUserName); socketChannel.pipeline().addLast(nettyClientHandler); } }); ChannelFuture channelFuture = bootstrap.connect(host, port).sync(); if (channelFuture.isSuccess()) { new Thread(new Runnable() { @Override public void run() { Scanner sc = new Scanner(System.in); while (sc.hasNext()){ MsgBody msgBody = new MsgBody(); msgBody.setSendUserName(sendUserName); msgBody.setMsg(sc.next()); nettyClientHandler.sendMsg(JSONObject.toJSONString(msgBody)); } } }).start(); System.err.println(sendUserName+"连接服务器成功"); } channelFuture.channel().closeFuture().sync(); } finally { eventLoopGroup.shutdownGracefully(); } } } 

6、新建2个main函数，模拟两个客户端

    public static void main(String[] args) throws InterruptedException {
        new NettyClient(10086, "localhost","tom");
    }
}

    public static void main(String[] args) throws InterruptedException {
        new NettyClient(10086, "localhost","jack");
    }
}

7、启动nettyServer，main1和main2
在main1输入 jack,你好，
在main2输入 tom,hello，我很好
server显示

 

main1显示

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main2显示

 

github代码： https://github.com/hd-eujian/netty-im.git

码云： https://gitee.com/guoeryyj/netty-im.git

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