DelimiterBasedFrameDecoder 分割符解码器的使用

DelimiterBasedFrameDecoder 分割符解码器的使用，将消息使用$$分割，解决TCP粘包问题

import io.netty.bootstrap.ServerBootstrap;
import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.*;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioServerSocketChannel;
import io.netty.handler.codec.DelimiterBasedFrameDecoder;
import io.netty.handler.codec.string.StringDecoder;
import io.netty.handler.logging.LogLevel;
import io.netty.handler.logging.LoggingHandler;

import java.net.InetSocketAddress;

/**
 * DelimiterBasedFrameDecoder 分割符解码器的使用
 */
public class EchoServer {
    public static void main(String...args) throws InterruptedException {
        EventLoopGroup parent = new NioEventLoopGroup();
        EventLoopGroup child = new NioEventLoopGroup();
        try {
            ServerBootstrap b = new ServerBootstrap();
            b.group(parent, child)
                    .localAddress(new InetSocketAddress(8080))
                    .channel(NioServerSocketChannel.class)
                    .option(ChannelOption.SO_BACKLOG, 100)
                    .handler(new LoggingHandler(LogLevel.INFO))
                    .childHandler(new ChannelInitializer<SocketChannel>() {
                        @Override
                        protected void initChannel(SocketChannel ch) throws Exception {
                            // 使用$$作为分割符
                            ByteBuf delimiter = Unpooled.copiedBuffer("$$".getBytes());
                            ch.pipeline().addLast(new DelimiterBasedFrameDecoder(1024, delimiter));
                            ch.pipeline().addLast(new StringDecoder());
                            ch.pipeline().addLast(new EchoServerHandler());
                        }
                    });
            ChannelFuture f = b.bind().sync();
            f.channel().closeFuture().sync();
        }finally {
            parent.shutdownGracefully().sync();
            child.shutdownGracefully().sync();
        }
    }

    @ChannelHandler.Sharable
    private static class EchoServerHandler extends ChannelInboundHandlerAdapter{
        int counter = 0;

        @Override
        public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
            String body = (String) msg;
            System.out.println("The server receive order:" + body + "; the counter is:" + ++counter);
            // msg会被DelimiterBasedFrameDecoder过滤掉$$，发送消息需要加上
            body += "$$";
            ByteBuf echo = Unpooled.copiedBuffer(body.getBytes());
            ctx.writeAndFlush(echo);
        }

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

import io.netty.bootstrap.Bootstrap;
import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.*;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioSocketChannel;
import io.netty.handler.codec.DelimiterBasedFrameDecoder;
import io.netty.handler.codec.string.StringDecoder;


import java.net.InetSocketAddress;

/**
 * DelimiterBasedFrameDecoder 分割符解码器的使用
 */
public class EchoClient {
    public static void main(String... args) throws InterruptedException {
        EventLoopGroup group = new NioEventLoopGroup();
        try {
            Bootstrap b = new Bootstrap();
            b.group(group)
                    .channel(NioSocketChannel.class)
                    .option(ChannelOption.TCP_NODELAY, true)
                    .remoteAddress(new InetSocketAddress(8080))
                    .handler(new ChannelInitializer<SocketChannel>() {
                        @Override
                        protected void initChannel(SocketChannel ch) throws Exception {
                            // 使用$$作为分割符
                            ByteBuf delimiter = Unpooled.copiedBuffer("$$".getBytes());
                            ch.pipeline().addLast(new DelimiterBasedFrameDecoder(1024, delimiter));
                            ch.pipeline().addLast(new StringDecoder());
                            ch.pipeline().addLast(new EchoClientHandler());
                        }
                    });
            ChannelFuture f = b.connect().sync();
            f.channel().closeFuture().sync();
        } finally {
            group.shutdownGracefully().sync();
        }
    }

    private static class EchoClientHandler extends ChannelInboundHandlerAdapter {
        int counter = 0;
        static final String REQ = "Hi, Welcome to Netty.$$";

        @Override
        public void channelActive(ChannelHandlerContext ctx) throws Exception {
            for (int i = 0; i < 10; i++) {
                ctx.writeAndFlush(Unpooled.copiedBuffer(REQ.getBytes()));
            }
        }

        @Override
        public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
            System.out.println("This is:" + ++counter + ",receive order:" + msg);
        }

        @Override
        public void channelReadComplete(ChannelHandlerContext ctx) throws Exception {
            ctx.flush();
        }

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