netty realizes simple communication between client and server

netty realizes simple communication between client and server

I won't say much here, just go to the code.

Server side

import io.netty.bootstrap.ServerBootstrap;
import io.netty.buffer.ByteBuf;
import io.netty.channel.*;
import io.netty.channel.group.ChannelGroup;
import io.netty.channel.group.DefaultChannelGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioServerSocketChannel;
import io.netty.util.concurrent.GlobalEventExecutor;

public class Server {
    
    
	// 管理连接的client
    public static ChannelGroup clients = new DefaultChannelGroup(GlobalEventExecutor.INSTANCE);

    public static void main(String[] args) {
    
    
        Server server = new Server();
        server.serverStart();
    }

    public void serverStart() {
    
    
        EventLoopGroup bossGroup = new NioEventLoopGroup(1); // 负责连接 用来accept
        EventLoopGroup workerGroup = new NioEventLoopGroup(2); // 负责处理

        ServerBootstrap sb = new ServerBootstrap(); // 辅助启动类
        try {
    
    
            ChannelFuture f = sb.group(bossGroup,workerGroup) // 指定线程池组
                    .channel(NioServerSocketChannel.class)
                    .childHandler(new ChannelInitializer<SocketChannel>() {
    
    
                        @Override
                        protected void initChannel(SocketChannel socketChannel) throws Exception {
    
    
                            socketChannel.pipeline()
                                .addLast(new ServerChildHandler());
                        }
                    })
                    .bind(9999)
                    .sync();
            f.channel().closeFuture().sync(); // close->ChannelFuture
        } catch (InterruptedException e) {
    
    
            e.printStackTrace();
        }finally {
    
    
            workerGroup.shutdownGracefully();
            bossGroup.shutdownGracefully();
        }
    }
}

class ServerChildHandler extends ChannelInboundHandlerAdapter{
    
    
    @Override
    public void channelActive(ChannelHandlerContext ctx) throws Exception {
    
    
        Server.clients.add(ctx.channel());
    }

    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
    
    
        cause.printStackTrace();
        // 删除出现异常的客户端channel，并关闭连接
        Server.clients.remove(ctx.channel());
        ctx.close();
    }
    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
    
    
        System.out.println("channelRead");
        ByteBuf buf = (ByteBuf)msg;
//        ctx.writeAndFlush(buf);
        System.out.println(buf);
        Server.clients.writeAndFlush(buf); // 将Server端接收到的信息广播到client端
    }
}

Client side

import io.netty.bootstrap.Bootstrap;
import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.Channel;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelFutureListener;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.nio.NioSocketChannel;

public class Client {
    
    

    public void connect(){
    
    
        // 线程池(事件处理线程池)
        NioEventLoopGroup group = new NioEventLoopGroup();
        // 辅助启动类
        Bootstrap b = new Bootstrap();
        try {
    
    
            ChannelFuture cf = b.group(group) // 把线程池放进来
                    .channel(NioSocketChannel.class)
                    .handler(new ClientChannelInitializer())
                    .connect("localhost",9999);
            cf.addListener((ChannelFutureListener) channelFuture -> {
    
    
                if(!channelFuture.isSuccess()){
    
    
                    System.out.println("not connected!");
                }else{
    
    
                    System.out.println("connected!");
                }
            }).sync();
            cf.channel().closeFuture().sync();
        } catch (InterruptedException e) {
    
    
            e.printStackTrace();
        } finally {
    
    
            group.shutdownGracefully();
        }
    }
    public static void main(String[] args) throws Exception {
    
    
        Client c = new Client();
        c.connect();
    }
}

ClientHandler

import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandlerAdapter;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.socket.SocketChannel;
import io.netty.util.ReferenceCountUtil;

public class ClientChannelInitializer extends ChannelInitializer<SocketChannel> {
    
    
    protected void initChannel(SocketChannel socketChannel) throws Exception {
    
    
        socketChannel.pipeline()
                .addLast(new ClientHandler()); // 处理channelRead,read()时才经过这个
    }
}

class ClientHandler extends ChannelInboundHandlerAdapter {
    
    
    @Override
    public void channelActive(ChannelHandlerContext ctx) throws Exception {
    
    
        // channel 第一次连上可用，写出一个字符串
        ByteBuf buf = Unpooled.copiedBuffer("hello".getBytes());
        ctx.writeAndFlush(buf); // 自动释放资源
    }
    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
    
    
        ByteBuf buf=null;
        try {
    
    
            buf = (ByteBuf)msg;
            System.out.println(buf);
        }finally {
    
    
            if (buf != null) {
    
    
                ReferenceCountUtil.release(buf);
            }
        }
    }
}

The above example can simply realize the communication between the client and the server