netty(一) 利用 LineBasedFrameDecoder，StringDecoder解决TCP粘包/拆包问题
【摘要】 .一，TCP粘包/拆包问题图示
产生TCP粘包/拆包问题如下几点：
TCP粘包/拆包问题解决方案：
二，利用 LineBasedFrameDecoder，StringDecoder解决TCP粘包/拆包问题
server端代码示例：
package nettyDemo3; import io.netty.bootstrap.ServerBoot...
.一，TCP粘包/拆包问题图示
产生TCP粘包/拆包问题如下几点：
TCP粘包/拆包问题解决方案：
二，利用 LineBasedFrameDecoder，StringDecoder解决TCP粘包/拆包问题
server端代码示例：
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package nettyDemo3;
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import io.netty.bootstrap.ServerBootstrap;
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import io.netty.buffer.ByteBuf;
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import io.netty.buffer.Unpooled;
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import io.netty.channel.ChannelFuture;
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import io.netty.channel.ChannelHandlerAdapter;
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import io.netty.channel.ChannelHandlerContext;
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import io.netty.channel.ChannelInitializer;
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import io.netty.channel.ChannelOption;
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import io.netty.channel.EventLoopGroup;
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import io.netty.channel.nio.NioEventLoopGroup;
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import io.netty.channel.socket.SocketChannel;
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import io.netty.channel.socket.nio.NioServerSocketChannel;
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import io.netty.handler.codec.LineBasedFrameDecoder;
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import io.netty.handler.codec.string.StringDecoder;
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public class TimeServerHanler extends ChannelHandlerAdapter {
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private int counter; // 计数器
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/**
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* 抛异常会调用此方法
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*/
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@Override
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public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
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// TODO Auto-generated method stub
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// super.exceptionCaught(ctx, cause);
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cause.printStackTrace();
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ctx.close();
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}
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/**
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* 读取客户端回应的消息
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*/
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@Override
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public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
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// TODO Auto-generated method stub
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// super.channelRead(ctx, msg);
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// ByteBuf buf = (ByteBuf) msg;
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// byte[] bytes = new byte[buf.readableBytes()];
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// buf.readBytes(bytes);
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// String body = new String(bytes, "UTF-8");
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// System.getProperty("line.separator") 换行符
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String body = (String) msg;
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System.out.println(body + "【第" + (++counter) + "次收到客户端的消息】");
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String result = "i am server" + System.getProperty("line.separator");
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ByteBuf buf2 = Unpooled.copiedBuffer(result.getBytes());
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ctx.write(buf2);
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}
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/**
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* 读取完成之后会调用此方法
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*/
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@Override
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public void channelReadComplete(ChannelHandlerContext ctx) throws Exception {
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// TODO Auto-generated method stub
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// super.channelReadComplete(ctx);
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ctx.flush();
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System.out.println("读取完成");
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}
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public static void main(String[] args) {
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// 配置服务端线程组，一个负责连接 ，一个负责读写
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EventLoopGroup boss = new NioEventLoopGroup();
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EventLoopGroup worker = new NioEventLoopGroup();
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try {
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// 创建服务端辅助启动类并设置参数
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ServerBootstrap bootstrap = new ServerBootstrap();
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bootstrap.group(boss, worker).channel(NioServerSocketChannel.class).option(ChannelOption.SO_BACKLOG, 1024)
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.handler(new LoggingHandler(LogLevel.INFO))
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.childHandler(new ChannelInitializer<SocketChannel>() {
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@Override
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protected void initChannel(SocketChannel ch) throws Exception {
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// TODO Auto-generated method stub
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// 添加回车换行符解码器
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ch.pipeline().addLast(new LineBasedFrameDecoder(1024));
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ch.pipeline().addLast(new StringDecoder());
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ch.pipeline().addLast(new TimeServerHanler());
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}
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});
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int inetPort = 8080;
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// 绑定端口，并开始阻塞等待客户端的连接
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ChannelFuture f = bootstrap.bind(inetPort).sync();
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f.channel().closeFuture().sync();
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} catch (Exception e) {
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e.printStackTrace();
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} finally {
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// 优雅退出，释放线程池资源
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boss.shutdownGracefully();
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worker.shutdownGracefully();
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}
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}
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}
client端代码示例：
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package nettyDemo3;
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import org.omg.PortableServer.POA;
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import io.netty.bootstrap.Bootstrap;
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import io.netty.buffer.ByteBuf;
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import io.netty.buffer.Unpooled;
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import io.netty.channel.Channel;
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import io.netty.channel.ChannelFuture;
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import io.netty.channel.ChannelHandlerAdapter;
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import io.netty.channel.ChannelHandlerContext;
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import io.netty.channel.ChannelInitializer;
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import io.netty.channel.ChannelOption;
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import io.netty.channel.EventLoopGroup;
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import io.netty.channel.nio.NioEventLoopGroup;
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import io.netty.channel.socket.SocketChannel;
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import io.netty.channel.socket.nio.NioSocketChannel;
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import io.netty.handler.codec.LineBasedFrameDecoder;
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import io.netty.handler.codec.string.StringDecoder;
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public class TimeClientHandler extends ChannelHandlerAdapter {
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private int counter;
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/**
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* 抛异常会调用此方法
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*/
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@Override
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public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
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// TODO Auto-generated method stub
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// super.exceptionCaught(ctx, cause);
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ctx.close();
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cause.printStackTrace();
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}
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/**
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* 当客户端成功连接上服务端之后会调用此方法
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*/
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@Override
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public void channelActive(ChannelHandlerContext ctx) throws Exception {
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// TODO Auto-generated method stub
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// super.channelActive(ctx);
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byte[] msg = ("i am clien" + System.getProperty("line.separator")).getBytes();
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ByteBuf buf = null;
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for (int i = 0; i < 50; i++) {
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buf = Unpooled.buffer(msg.length);
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buf.writeBytes(msg);
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ctx.writeAndFlush(buf);
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}
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}
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/**
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* 读取服务端回应的消息
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*/
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@Override
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public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
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// TODO Auto-generated method stub
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// super.channelRead(ctx, msg);
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// ByteBuf buf = (ByteBuf) msg;
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// byte[] bytes = new byte[buf.readableBytes()];
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// buf.readBytes(bytes);
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// String body = new String(bytes, "UTF-8");
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String body = (String) msg;
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System.out.println(body + "【第" + (++counter) + "次收到服务端的消息】");
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}
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public static void main(String[] args) {
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// 配置客户端端线程组负责读写
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EventLoopGroup work = new NioEventLoopGroup();
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try {
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// 创建客户端的辅助启动类并设置参数
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Bootstrap bootstrap = new Bootstrap();
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bootstrap.group(work).channel(NioSocketChannel.class).option(ChannelOption.TCP_NODELAY, true)
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.handler(new ChannelInitializer<SocketChannel>() {
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@Override
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protected void initChannel(SocketChannel ch) throws Exception {
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// TODO Auto-generated method stub
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// 添加解码器
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ch.pipeline().addLast(new LineBasedFrameDecoder(1024));
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ch.pipeline().addLast(new StringDecoder());
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ch.pipeline().addLast(new TimeClientHandler());
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}
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});
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final String host = "127.0.0.1";
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final int port = 8080;
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// 连接服务端
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ChannelFuture future = bootstrap.connect(host, port).sync();
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future.channel().closeFuture().sync();
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} catch (Exception e) {
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// TODO: handle exception
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} finally {
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// 优雅退出，释放线程池资源
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work.shutdownGracefully();
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}
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}
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}
分别运行客户端和服务端实例，看到控制台输出以下图片中的内容，说明成功解决tcp粘包/拆包问题。
附： netty利用DelimiterBasedFrameDecoder 和 FixedLengthFrameDecoder 也可以按需自定义解码实现粘包/拆包问题
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//添加自定义以$_为分隔符的解码器
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ByteBuf buf = Unpooled.copiedBuffer("$_".getBytes());
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ch.pipeline().addLast(new DelimiterBasedFrameDecoder(1024,buf));
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//添加固定长度解码器
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ch.pipeline().addLast(new FixedLengthFrameDecoder(13));
文章来源: blog.csdn.net，作者：血煞风雨城2018，版权归原作者所有，如需转载，请联系作者。
原文链接：blog.csdn.net/qq_31905135/article/details/81736896
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