netty权威指南学习笔记四——TCP粘包/拆包之粘包问题解决
发生了粘包，我们需要将其清晰的进行拆包处理，这里采用LineBasedFrameDecoder来解决
LineBasedFrameDecoder的工作原理是它依次遍历ByteBuf中的可读字节，判断看是否有“\n”或“\r\n”，如果有，就以此为结束位置，从可读索引到结束位置区间的字节就组成一行，它是以换行为结束标志的编码器，支持携带结束符或者不携带结束符两种方式，同时支持配置单行最大长度，如果连续读取到的最大长度后仍没有发现换行符，就会抛出异常，同时忽略掉之前读到的异常码流。
StringDecoder的功能非常简单，就是将接收到的对象转换为字符串，然后继续调用后面的Handler.
LineBasedFrameDecoder+StringDecoder组合就是按行切换的文本解码器。
主要思路是改造客户端和服务端的处理IO的类之前添加相应解码器，解码器之后才去调用IO处理类的Handler。
客户端改造的代码部分
TheClientServer
在处理IO的类initChannel（）方法中调用处理IO类前添加相关解码的方法
public class ClientChildHandler extends ChannelInitializer<SocketChannel>{
@Override
protected void initChannel(SocketChannel socketChannel) throws Exception {
socketChannel.pipeline().addLast(new LineBasedFrameDecoder(1024))//添加解码器，遍历ByteBuf并组行
.addLast(new StringDecoder())//添加解码器，将接收到的对象转换为字符串
.addLast(new TimeClientHandler());
}
}
同时在接收请求或相应的channelRead(ChannelHandlerContext ctx, Object msg)方法中进行相关改造，直接用String接收即可，这是因为，在这之前的解码器已经将发送过来的ByteBuf类型进行读取后并转换为String格式了
TimeClientHandler
@Override
public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
/* ByteBuf byteBuf = (ByteBuf) msg;
byte[] req = new byte[byteBuf.readableBytes()];
byteBuf.readBytes(req);
String body = new String(req,"utf-8");*/
String body = (String) msg;
System.out.println("Now is:"+body+";The client count is:"+ ++count);
}
服务端改造的代码部分
TimeServer
// IO处理类的初始化
private class ChildHandler extends ChannelInitializer {
@Override
protected void initChannel(Channel channel) throws Exception {
channel.pipeline()
.addLast(new LineBasedFrameDecoder(1024))
.addLast(new StringDecoder())
.addLast(new TimeServerHandler());
}
}
TimeServerHandler
@Override
public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
/* ByteBuf byteBuf = (ByteBuf) msg;//将请求转为ByteBuf缓冲区
byte[] req = new byte[byteBuf.readableBytes()];//获取byteBuf的可读字节数
byteBuf.readBytes(req);//将缓冲区字节数组复制到req数组中
String body = new String(req,"utf-8")//转换为字符串
//改造去掉客户端传递过来的换行符号，模拟故障造成粘包问题
.substring(0,req.length-System.lineSeparator().length());*/
String body = (String) msg;
System.out.println("the time server receive order:"+body+"the count is:"+ ++count);
// 处理IO内容
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());//返回客户端的消息转化为ByteBuf对象
ctx.write(resp);//将待应答消息放入缓冲数组中
}
其余代码与上一小节完全相同
运行结果
客户端
11:55:37.187 [nioEventLoopGroup-2-1] DEBUG io.netty.util.Recycler - -Dio.netty.recycler.maxSharedCapacityFactor: 2
11:55:37.187 [nioEventLoopGroup-2-1] DEBUG io.netty.util.Recycler - -Dio.netty.recycler.linkCapacity: 16
11:55:37.187 [nioEventLoopGroup-2-1] DEBUG io.netty.util.Recycler - -Dio.netty.recycler.ratio: 8
Now is:Sat Jul 21 11:55:37 CST 2018;The client count is:1
Now is:Sat Jul 21 11:55:37 CST 2018;The client count is:2
Now is:Sat Jul 21 11:55:37 CST 2018;The client count is:3
Now is:Sat Jul 21 11:55:37 CST 2018;The client count is:4
Now is:Sat Jul 21 11:55:37 CST 2018;The client count is:5
Now is:Sat Jul 21 11:55:37 CST 2018;The client count is:6
Now is:Sat Jul 21 11:55:37 CST 2018;The client count is:7
Now is:Sat Jul 21 11:55:37 CST 2018;The client count is:8
Now is:Sat Jul 21 11:55:37 CST 2018;The client count is:9
Now is:Sat Jul 21 11:55:37 CST 2018;The client count is:10
Now is:Sat Jul 21 11:55:37 CST 2018;The client count is:11
Now is:Sat Jul 21 11:55:37 CST 2018;The client count is:12
Now is:Sat Jul 21 11:55:37 CST 2018;The client count is:13
Now is:Sat Jul 21 11:55:37 CST 2018;The client count is:14
Now is:Sat Jul 21 11:55:37 CST 2018;The client count is:15
Now is:Sat Jul 21 11:55:37 CST 2018;The client count is:16
Now is:Sat Jul 21 11:55:37 CST 2018;The client count is:17
Now is:Sat Jul 21 11:55:37 CST 2018;The client count is:18
Now is:Sat Jul 21 11:55:37 CST 2018;The client count is:19
Now is:Sat Jul 21 11:55:37 CST 2018;The client count is:20
Now is:Sat Jul 21 11:55:37 CST 2018;The client count is:21
Now is:Sat Jul 21 11:55:37 CST 2018;The client count is:22
Now is:Sat Jul 21 11:55:37 CST 2018;The client count is:23
Now is:Sat Jul 21 11:55:37 CST 2018;The client count is:24
Now is:Sat Jul 21 11:55:37 CST 2018;The client count is:25
Now is:Sat Jul 21 11:55:37 CST 2018;The client count is:26
Now is:Sat Jul 21 11:55:37 CST 2018;The client count is:27
Now is:Sat Jul 21 11:55:37 CST 2018;The client count is:28
Now is:Sat Jul 21 11:55:37 CST 2018;The client count is:29
Now is:Sat Jul 21 11:55:37 CST 2018;The client count is:30
Now is:Sat Jul 21 11:55:37 CST 2018;The client count is:31
Now is:Sat Jul 21 11:55:37 CST 2018;The client count is:32
Now is:Sat Jul 21 11:55:37 CST 2018;The client count is:33
Now is:Sat Jul 21 11:55:37 CST 2018;The client count is:34
Now is:Sat Jul 21 11:55:37 CST 2018;The client count is:35
Now is:Sat Jul 21 11:55:37 CST 2018;The client count is:36
Now is:Sat Jul 21 11:55:37 CST 2018;The client count is:37
Now is:Sat Jul 21 11:55:37 CST 2018;The client count is:38
Now is:Sat Jul 21 11:55:37 CST 2018;The client count is:39
Now is:Sat Jul 21 11:55:37 CST 2018;The client count is:40
Now is:Sat Jul 21 11:55:37 CST 2018;The client count is:41
Now is:Sat Jul 21 11:55:37 CST 2018;The client count is:42
Now is:Sat Jul 21 11:55:37 CST 2018;The client count is:43
Now is:Sat Jul 21 11:55:37 CST 2018;The client count is:44
Now is:Sat Jul 21 11:55:37 CST 2018;The client count is:45
Now is:Sat Jul 21 11:55:37 CST 2018;The client count is:46
Now is:Sat Jul 21 11:55:37 CST 2018;The client count is:47
Now is:Sat Jul 21 11:55:37 CST 2018;The client count is:48
Now is:Sat Jul 21 11:55:37 CST 2018;The client count is:49
Now is:Sat Jul 21 11:55:37 CST 2018;The client count is:50
Now is:Sat Jul 21 11:55:37 CST 2018;The client count is:51
Now is:Sat Jul 21 11:55:37 CST 2018;The client count is:52
Now is:Sat Jul 21 11:55:37 CST 2018;The client count is:53
Now is:Sat Jul 21 11:55:37 CST 2018;The client count is:54
Now is:Sat Jul 21 11:55:37 CST 2018;The client count is:55
Now is:Sat Jul 21 11:55:37 CST 2018;The client count is:56
Now is:Sat Jul 21 11:55:37 CST 2018;The client count is:57
Now is:Sat Jul 21 11:55:37 CST 2018;The client count is:58
Now is:Sat Jul 21 11:55:37 CST 2018;The client count is:59
Now is:Sat Jul 21 11:55:37 CST 2018;The client count is:60
Now is:Sat Jul 21 11:55:37 CST 2018;The client count is:61
Now is:Sat Jul 21 11:55:37 CST 2018;The client count is:62
Now is:Sat Jul 21 11:55:37 CST 2018;The client count is:63
Now is:Sat Jul 21 11:55:37 CST 2018;The client count is:64
Now is:Sat Jul 21 11:55:37 CST 2018;The client count is:65
Now is:Sat Jul 21 11:55:37 CST 2018;The client count is:66
Now is:Sat Jul 21 11:55:37 CST 2018;The client count is:67
Now is:Sat Jul 21 11:55:37 CST 2018;The client count is:68
Now is:Sat Jul 21 11:55:37 CST 2018;The client count is:69
Now is:Sat Jul 21 11:55:37 CST 2018;The client count is:70
Now is:Sat Jul 21 11:55:37 CST 2018;The client count is:71
Now is:Sat Jul 21 11:55:37 CST 2018;The client count is:72
Now is:Sat Jul 21 11:55:37 CST 2018;The client count is:73
Now is:Sat Jul 21 11:55:37 CST 2018;The client count is:74
Now is:Sat Jul 21 11:55:37 CST 2018;The client count is:75
Now is:Sat Jul 21 11:55:37 CST 2018;The client count is:76
Now is:Sat Jul 21 11:55:37 CST 2018;The client count is:77
Now is:Sat Jul 21 11:55:37 CST 2018;The client count is:78
Now is:Sat Jul 21 11:55:37 CST 2018;The client count is:79
Now is:Sat Jul 21 11:55:37 CST 2018;The client count is:80
Now is:Sat Jul 21 11:55:37 CST 2018;The client count is:81
Now is:Sat Jul 21 11:55:37 CST 2018;The client count is:82
Now is:Sat Jul 21 11:55:37 CST 2018;The client count is:83
Now is:Sat Jul 21 11:55:37 CST 2018;The client count is:84
Now is:Sat Jul 21 11:55:37 CST 2018;The client count is:85
Now is:Sat Jul 21 11:55:37 CST 2018;The client count is:86
Now is:Sat Jul 21 11:55:37 CST 2018;The client count is:87
Now is:Sat Jul 21 11:55:37 CST 2018;The client count is:88
Now is:Sat Jul 21 11:55:37 CST 2018;The client count is:89
Now is:Sat Jul 21 11:55:37 CST 2018;The client count is:90
Now is:Sat Jul 21 11:55:37 CST 2018;The client count is:91
Now is:Sat Jul 21 11:55:37 CST 2018;The client count is:92
Now is:Sat Jul 21 11:55:37 CST 2018;The client count is:93
Now is:Sat Jul 21 11:55:37 CST 2018;The client count is:94
Now is:Sat Jul 21 11:55:37 CST 2018;The client count is:95
Now is:Sat Jul 21 11:55:37 CST 2018;The client count is:96
Now is:Sat Jul 21 11:55:37 CST 2018;The client count is:97
Now is:Sat Jul 21 11:55:37 CST 2018;The client count is:98
Now is:Sat Jul 21 11:55:37 CST 2018;The client count is:99
Now is:Sat Jul 21 11:55:37 CST 2018;The client count is:100
服务端
11:55:37.276 [nioEventLoopGroup-3-1] DEBUG io.netty.util.ResourceLeakDetectorFactory - Loaded default ResourceLeakDetector: io.netty.util.ResourceLeakDetector@73046a4d
the time server receive order:QUERY TIME ORDERthe count is:1
the time server receive order:QUERY TIME ORDERthe count is:2
the time server receive order:QUERY TIME ORDERthe count is:3
the time server receive order:QUERY TIME ORDERthe count is:4
the time server receive order:QUERY TIME ORDERthe count is:5
the time server receive order:QUERY TIME ORDERthe count is:6
the time server receive order:QUERY TIME ORDERthe count is:7
the time server receive order:QUERY TIME ORDERthe count is:8
the time server receive order:QUERY TIME ORDERthe count is:9
the time server receive order:QUERY TIME ORDERthe count is:10
the time server receive order:QUERY TIME ORDERthe count is:11
the time server receive order:QUERY TIME ORDERthe count is:12
the time server receive order:QUERY TIME ORDERthe count is:13
the time server receive order:QUERY TIME ORDERthe count is:14
the time server receive order:QUERY TIME ORDERthe count is:15
the time server receive order:QUERY TIME ORDERthe count is:16
the time server receive order:QUERY TIME ORDERthe count is:17
the time server receive order:QUERY TIME ORDERthe count is:18
the time server receive order:QUERY TIME ORDERthe count is:19
the time server receive order:QUERY TIME ORDERthe count is:20
the time server receive order:QUERY TIME ORDERthe count is:21
the time server receive order:QUERY TIME ORDERthe count is:22
the time server receive order:QUERY TIME ORDERthe count is:23
the time server receive order:QUERY TIME ORDERthe count is:24
the time server receive order:QUERY TIME ORDERthe count is:25
the time server receive order:QUERY TIME ORDERthe count is:26
the time server receive order:QUERY TIME ORDERthe count is:27
the time server receive order:QUERY TIME ORDERthe count is:28
the time server receive order:QUERY TIME ORDERthe count is:29
the time server receive order:QUERY TIME ORDERthe count is:30
the time server receive order:QUERY TIME ORDERthe count is:31
the time server receive order:QUERY TIME ORDERthe count is:32
the time server receive order:QUERY TIME ORDERthe count is:33
the time server receive order:QUERY TIME ORDERthe count is:34
the time server receive order:QUERY TIME ORDERthe count is:35
the time server receive order:QUERY TIME ORDERthe count is:36
the time server receive order:QUERY TIME ORDERthe count is:37
the time server receive order:QUERY TIME ORDERthe count is:38
the time server receive order:QUERY TIME ORDERthe count is:39
the time server receive order:QUERY TIME ORDERthe count is:40
the time server receive order:QUERY TIME ORDERthe count is:41
the time server receive order:QUERY TIME ORDERthe count is:42
the time server receive order:QUERY TIME ORDERthe count is:43
the time server receive order:QUERY TIME ORDERthe count is:44
the time server receive order:QUERY TIME ORDERthe count is:45
the time server receive order:QUERY TIME ORDERthe count is:46
the time server receive order:QUERY TIME ORDERthe count is:47
the time server receive order:QUERY TIME ORDERthe count is:48
the time server receive order:QUERY TIME ORDERthe count is:49
the time server receive order:QUERY TIME ORDERthe count is:50
the time server receive order:QUERY TIME ORDERthe count is:51
the time server receive order:QUERY TIME ORDERthe count is:52
the time server receive order:QUERY TIME ORDERthe count is:53
the time server receive order:QUERY TIME ORDERthe count is:54
the time server receive order:QUERY TIME ORDERthe count is:55
the time server receive order:QUERY TIME ORDERthe count is:56
the time server receive order:QUERY TIME ORDERthe count is:57
the time server receive order:QUERY TIME ORDERthe count is:58
the time server receive order:QUERY TIME ORDERthe count is:59
the time server receive order:QUERY TIME ORDERthe count is:60
the time server receive order:QUERY TIME ORDERthe count is:61
the time server receive order:QUERY TIME ORDERthe count is:62
the time server receive order:QUERY TIME ORDERthe count is:63
the time server receive order:QUERY TIME ORDERthe count is:64
the time server receive order:QUERY TIME ORDERthe count is:65
the time server receive order:QUERY TIME ORDERthe count is:66
the time server receive order:QUERY TIME ORDERthe count is:67
the time server receive order:QUERY TIME ORDERthe count is:68
the time server receive order:QUERY TIME ORDERthe count is:69
the time server receive order:QUERY TIME ORDERthe count is:70
the time server receive order:QUERY TIME ORDERthe count is:71
the time server receive order:QUERY TIME ORDERthe count is:72
the time server receive order:QUERY TIME ORDERthe count is:73
the time server receive order:QUERY TIME ORDERthe count is:74
the time server receive order:QUERY TIME ORDERthe count is:75
the time server receive order:QUERY TIME ORDERthe count is:76
the time server receive order:QUERY TIME ORDERthe count is:77
the time server receive order:QUERY TIME ORDERthe count is:78
the time server receive order:QUERY TIME ORDERthe count is:79
the time server receive order:QUERY TIME ORDERthe count is:80
the time server receive order:QUERY TIME ORDERthe count is:81
the time server receive order:QUERY TIME ORDERthe count is:82
the time server receive order:QUERY TIME ORDERthe count is:83
the time server receive order:QUERY TIME ORDERthe count is:84
the time server receive order:QUERY TIME ORDERthe count is:85
the time server receive order:QUERY TIME ORDERthe count is:86
the time server receive order:QUERY TIME ORDERthe count is:87
the time server receive order:QUERY TIME ORDERthe count is:88
the time server receive order:QUERY TIME ORDERthe count is:89
the time server receive order:QUERY TIME ORDERthe count is:90
the time server receive order:QUERY TIME ORDERthe count is:91
the time server receive order:QUERY TIME ORDERthe count is:92
the time server receive order:QUERY TIME ORDERthe count is:93
the time server receive order:QUERY TIME ORDERthe count is:94
the time server receive order:QUERY TIME ORDERthe count is:95
the time server receive order:QUERY TIME ORDERthe count is:96
the time server receive order:QUERY TIME ORDERthe count is:97
the time server receive order:QUERY TIME ORDERthe count is:98
the time server receive order:QUERY TIME ORDERthe count is:99
the time server receive order:QUERY TIME ORDERthe count is:100
这样，就解决了粘包的问题。
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