Netty(2) 拆包、粘包的解决方案

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拆包、粘包的三种解决方案

  1. 消息定长，例如每个报文的大小固定为每200个字节，如果不够，空位补空格
  2. 在包尾增加特殊字符进行分隔，例如加回车等
  3. 消息分为消息头和消息体，在消息头中包含表示消息总长度的字段，然后进行业务处理

Netty解决TCP拆粘包问题

  1. 分隔符类 DelimiterBaseFrameDecorder(自定义分隔符)
  2. FixedLengthFrameDecoder(定长)

自定义分隔符的方式

Server.java

import io.netty.bootstrap.ServerBootstrap;
import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
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.NioServerSocketChannel;
import io.netty.handler.codec.DelimiterBasedFrameDecoder;
import io.netty.handler.codec.string.StringDecoder;

public class Server {
	public static void main(String[] args) throws Exception{
		//1 创建2个线程，一个是负责接收客户端的连接。一个是负责进行数据传输的
		EventLoopGroup pGroup = new NioEventLoopGroup();
		EventLoopGroup cGroup = new NioEventLoopGroup();
		
		//2 创建服务器辅助类
		ServerBootstrap b = new ServerBootstrap();
		b.group(pGroup, cGroup)
		 .channel(NioServerSocketChannel.class)
		 .option(ChannelOption.SO_BACKLOG, 1024)
		 // 1000 --> 990 1024 * 32  --> 1024 * 64
		 .childOption(ChannelOption.SO_SNDBUF, 32*1024)
		 .childOption(ChannelOption.SO_RCVBUF, 32*1024)
		 .childHandler(new ChannelInitializer<SocketChannel>() {
			@Override
			protected void initChannel(SocketChannel sc) throws Exception {
				//	设置特殊分隔符
				ByteBuf buf = Unpooled.copiedBuffer("$_".getBytes());
				sc.pipeline().addLast(new DelimiterBasedFrameDecoder(32 * 1024, buf));
				//	设置字符串形式的解码
				sc.pipeline().addLast(new StringDecoder());
				sc.pipeline().addLast(new ServerHandler());
			}
		});
		
		//4 绑定连接
		ChannelFuture cf = b.bind(8765).sync();
		
		//	等待服务器监听端口关闭
		cf.channel().closeFuture().sync();
		pGroup.shutdownGracefully();
		cGroup.shutdownGracefully();
	}
}

ServerHandler.java

import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandlerAdapter;

public class ServerHandler extends ChannelInboundHandlerAdapter {
	@Override
	public void channelActive(ChannelHandlerContext ctx) throws Exception {
		System.out.println(" server channel active... ");
	}
	@Override
	public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
		String request = (String)msg;
//		Thread.sleep(5000);
//		Random r = new Random();
//		Thread.sleep(100 * r.nextInt(5));
		System.out.println("Server :" + msg);
		String response = "服务器响应：" + msg + "$_";
		ctx.writeAndFlush(Unpooled.copiedBuffer(response.getBytes()));
	}

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

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

Client.java

import io.netty.bootstrap.Bootstrap;
import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
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 io.netty.handler.codec.DelimiterBasedFrameDecoder;
import io.netty.handler.codec.string.StringDecoder;

public class Client {
	public static void main(String[] args) throws Exception {
		EventLoopGroup group = new NioEventLoopGroup();
		Bootstrap b = new Bootstrap();
		b.group(group)
		 .channel(NioSocketChannel.class)
		 .option(ChannelOption.SO_SNDBUF, 32*1024)
		 .option(ChannelOption.SO_RCVBUF, 32*1024)		 
		 .handler(new ChannelInitializer<SocketChannel>() {
			@Override
			protected void initChannel(SocketChannel sc) throws Exception {
				//
				ByteBuf buf = Unpooled.copiedBuffer("$_".getBytes());
				sc.pipeline().addLast(new DelimiterBasedFrameDecoder(32 * 1024, buf));
				sc.pipeline().addLast(new StringDecoder());
				sc.pipeline().addLast(new ClientHandler());
			}
		});
		ChannelFuture cf = b.connect("127.0.0.1", 8765).sync();
		for(int i = 1 ; i <=10 ; i ++){			// 4 + 10 + $_ = 8
			cf.channel().writeAndFlush(Unpooled.wrappedBuffer(("消息" + i + "$_").getBytes()));
		}
		//	等待客户端端口关闭
		cf.channel().closeFuture().sync();
		group.shutdownGracefully();
	}
}

ClientHandler.java

import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandlerAdapter;
import io.netty.util.ReferenceCountUtil;

public class ClientHandler extends ChannelInboundHandlerAdapter{
	@Override
	public void channelActive(ChannelHandlerContext ctx) throws Exception {
		System.out.println("client channel active... ");
	}
	@Override
	public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
		try {
			String response = (String)msg;
			System.out.println("Client: " + response);
		} finally {
			ReferenceCountUtil.release(msg);
		}
	}

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

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

2. 定长的方式

Server.java

import io.netty.bootstrap.ServerBootstrap;
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.NioServerSocketChannel;
import io.netty.handler.codec.FixedLengthFrameDecoder;
import io.netty.handler.codec.string.StringDecoder;

public class Server {
	public static void main(String[] args) throws Exception{
		//1 创建2个线程，一个是负责接收客户端的连接。一个是负责进行数据传输的
		EventLoopGroup pGroup = new NioEventLoopGroup();
		EventLoopGroup cGroup = new NioEventLoopGroup();
		
		//2 创建服务器辅助类
		ServerBootstrap b = new ServerBootstrap();
		b.group(pGroup, cGroup)
		 .channel(NioServerSocketChannel.class)
		 .option(ChannelOption.SO_BACKLOG, 1024)
		 .option(ChannelOption.SO_SNDBUF, 32*1024)
		 .option(ChannelOption.SO_RCVBUF, 32*1024)
		 .childHandler(new ChannelInitializer<SocketChannel>() {
			@Override
			protected void initChannel(SocketChannel sc) throws Exception {
				//	设置定长字符串接收
				sc.pipeline().addLast(new FixedLengthFrameDecoder(5));
				//	设置字符串形式的解码
				sc.pipeline().addLast(new StringDecoder());
				sc.pipeline().addLast(new ServerHandler());
			}
		});
		
		//4 绑定连接
		ChannelFuture cf = b.bind(8765).sync();
		
		//	等待服务器监听端口关闭
		cf.channel().closeFuture().sync();
		pGroup.shutdownGracefully();
		cGroup.shutdownGracefully();
	}
}

ServerHandler.java

import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandlerAdapter;

public class ServerHandler extends ChannelInboundHandlerAdapter {
	@Override
	public void channelActive(ChannelHandlerContext ctx) throws Exception {
		System.out.println(" server channel active... ");
	}

	@Override
	public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
		String request = (String)msg;
		System.out.println("Server :" + msg);
		String response =  request ;
		ctx.writeAndFlush(Unpooled.copiedBuffer(response.getBytes()));
	}

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

	@Override
	public void exceptionCaught(ChannelHandlerContext ctx, Throwable t) throws Exception {
	}
}

Client.java

import io.netty.bootstrap.Bootstrap;
import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelInitializer;
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 io.netty.handler.codec.FixedLengthFrameDecoder;
import io.netty.handler.codec.string.StringDecoder;

public class Client {
	public static void main(String[] args) throws Exception {
		EventLoopGroup group = new NioEventLoopGroup();
		
		Bootstrap b = new Bootstrap();
		b.group(group)
		 .channel(NioSocketChannel.class)
		 .handler(new ChannelInitializer<SocketChannel>() {
			@Override
			protected void initChannel(SocketChannel sc) throws Exception {
				sc.pipeline().addLast(new FixedLengthFrameDecoder(5));
				sc.pipeline().addLast(new StringDecoder());
				sc.pipeline().addLast(new ClientHandler());
			}
		});
		
		ChannelFuture cf = b.connect("127.0.0.1", 8765).sync();
		
		cf.channel().writeAndFlush(Unpooled.wrappedBuffer("aaaaabbbbb".getBytes()));
		cf.channel().writeAndFlush(Unpooled.copiedBuffer("ccccccc  ".getBytes()));
		cf.channel().writeAndFlush(Unpooled.copiedBuffer("c   cc".getBytes()));
		//	等待客户端端口关闭
		cf.channel().closeFuture().sync();
		group.shutdownGracefully();
	}
}

ClientHandler.java

import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandlerAdapter;

public class ClientHandler extends ChannelInboundHandlerAdapter{
	@Override
	public void channelActive(ChannelHandlerContext ctx) throws Exception {
		System.out.println("client channel active... ");
	}

	@Override
	public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
		String response = (String)msg;
		System.out.println("Client: " + response);
	}

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

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