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上一篇：【Netty4.X】Unity客户端与Netty服务器的网络通信(一)
如图所示，假如客户端分别发送两个数据包D1和D2给服务端，由于服务端一次读取到的字节数是不确定的，故可能存在以下4中情况：
修改上一篇【Netty4.X】Unity客户端与Netty服务器的网络通信(一)的ServerHandler类代码。在类中申明一个计数常量count，当每读到一条消息后，就count++，然后发送应答消息给客户端，代码如下：
@Override
public void channelRead(ChannelHandlerContext ctx, Object msg)
throws Exception {
ByteBuf buf = (ByteBuf)msg;
byte[] req = new byte[buf.readableBytes()];
buf.readBytes(req);
String body = new String(req,"UTF-8").substring(0, req.length - System.getProperty("line.separator").length());
count++;
System.out.println("body"+body+";"+ ++count);
String currentTime = "QUERY TIME ORDER".equalsIgnoreCase(body)?
new Date(System.currentTimeMillis()).toString():"BAD ORDER";
ByteBuf resp = Unpooled.copiedBuffer(currentTime.getBytes());
ctx.writeAndFlush(resp);
}
修改HttpClient的send()方法，当客户端与服务器链路建立成功之后，循环发送100条消息类代码。
public void Send()
{
if(client == null)
{
start ();
}
byte[] buffer = Encoding.UTF8.GetBytes("userName:"+userName.text+" password"+password.text);
for(int i = 0;i < 100;i++)
{
client.Send(buffer);
}
}控制台(服务器)： +------------------------------------------------------------------+ 七月 07, 2016 8:09:35 下午 com.game.lll.net.HttpServer main 信息: 服务已启动... ad4ea569进来了 bodyuserName:aaa password:bbb ...此处省略36条 userName:aaa password:b;count:1 userName:aaa password:bbb ...此处省略36条 userName:aaa password;count:2 userName:aaa password:bbb ...此处省略22条 userName:aaa password:bbb;count:3 +------------------------------------------------------------------+服务端运行结果表明它只接收到三条消息，三条加起来一共是100条(如下图)。我们期待的是收到100条消息，每条消息都会包含一条“count:”.这说明发生了TCP粘包。
按照设计初衷，客户端应该收到100条AD ORDER消息，但实际上只收到了一条。
粘包的解决办法有很多，可以归纳如下。
在本案例中，我使用的是第2个解决办法在包尾增加回车换行符进行分割。
第一步：新建一个类ServerChannelHandler继承于ChannelInitializer，重点代码在26,27行，在原来的ServerHandler之前新增了两个解码器：LineBasedFrameDecoder和StringDecoder。代码如下
package com.game.lll.net;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.socket.SocketChannel;
import io.netty.handler.codec.LineBasedFrameDecoder;
import io.netty.handler.codec.string.StringDecoder;
public class ServerChannelHandler extends ChannelInitializer<SocketChannel>{
public static void main(String[] args) throws Exception {
int port = 8844;
if(args!=null&&args.length>0)
{
try {
port = Integer.valueOf(args[0]);
} catch (Exception e) {
// TODO: handle exception
}
}
System.out.println(port);
new HttpServer().bind(port);
}
@Override
protected void initChannel(SocketChannel ch) throws Exception {
ch.pipeline().addLast(new LineBasedFrameDecoder(1024));
ch.pipeline().addLast(new StringDecoder());
ch.pipeline().addLast(new ServerHandler());
}
}
第二部：修改原来的HttpServer类，修改代码如下。代码如下
package com.game.lll.net;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
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;
public class HttpServer {
private static Log log = LogFactory.getLog(HttpServer.class);
public void bind(int port) throws Exception {
log.info("服务器已启动");
////配置服务端的NIO线程组
EventLoopGroup bossGroup = new NioEventLoopGroup();
EventLoopGroup workerGroup = new NioEventLoopGroup();
try {
ServerBootstrap b = new ServerBootstrap();
b.group(bossGroup, workerGroup).channel(NioServerSocketChannel.class)
.childHandler(new ChannelInitializer<SocketChannel>() {
@Override
public void initChannel(SocketChannel ch) throws Exception {
ch.pipeline().addLast(new ServerChannelHandler());
}
}).option(ChannelOption.SO_BACKLOG, 128) //最大客户端连接数为128
.childOption(ChannelOption.SO_KEEPALIVE, true);
//绑定端口，同步等待成功
ChannelFuture f = b.bind(port).sync();
//等待服务端监听端口关闭
f.channel().closeFuture().sync();
} finally {
//优雅退出，释放线程池资源
workerGroup.shutdownGracefully();
bossGroup.shutdownGracefully();
}
}
}第三步修改ServerHandler类。代码如下
package com.game.lll.net;
import java.util.Date;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandlerAdapter;
public class ServerHandler extends ChannelInboundHandlerAdapter{
private static Log log = LogFactory.getLog(ServerHandler.class);
private int count = 0;
@Override
public void handlerAdded(ChannelHandlerContext ctx) throws Exception {
super.handlerAdded(ctx);
System.out.println(ctx.channel().id()+"进来了");
}
@Override
public void handlerRemoved(ChannelHandlerContext ctx) throws Exception {
super.handlerRemoved(ctx);
System.out.println(ctx.channel().id()+"离开了");
}
@Override
public void channelRead(ChannelHandlerContext ctx, Object msg)
throws Exception {
String body = (String)msg;
System.out.println("body"+body+";count:"+ ++count);
String currentTime = "QUERY TIME ORDER".equalsIgnoreCase(body)?new Date(System.currentTimeMillis()).toString():"BAD ORDER";
currentTime = currentTime+System.getProperty("line.separator");
ByteBuf resp = Unpooled.copiedBuffer(currentTime.getBytes());
ctx.writeAndFlush(resp);
}
@Override
public void channelReadComplete(ChannelHandlerContext ctx) throws Exception {
ctx.flush();
}
@Override
public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause)
throws Exception {
// TODO Auto-generated method stub
ctx.close();
}
}直接看第33行，修改前后代码比较。修改前：
ByteBuf buf = (ByteBuf)msg; byte[] req = new byte[buf.readableBytes()]; buf.readBytes(req); String body = new String(req,"UTF-8");
修改后：
String body = (String)msg;
byte[] buffer = Encoding.UTF8.GetBytes("userName:"+userName.text+" password:"+password.text+"\r\n");在每一条消息尾巴后添加“\r\n’”控制台(服务器)： +------------------------------------------------------------------+ 8844 七月 07, 2016 8:37:58 下午 com.game.lll.net.HttpServer bind 信息: 服务器已启动 04d575ff进来了 bodyuserName:aaa password:bbb;count:1 此处省略很多条...... bodyuserName:aaa password:bbb;count:99 bodyuserName:aaa password:bbb;count:100 +------------------------------------------------------------------+
本章参考书籍
<<Netty权威指南(第2版)>>
【游戏开发】Netty TCP粘包/拆包问题的解决办法(二)
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原文地址：http://blog.csdn.net/liulongling/article/details/51853083
