netty 解决TCP粘包与拆包问题(三)

今天使用netty的固定长度进行解码

固定长度解码的原理就是按照指定消息的长度对消息自动解码。

在netty实现中，只需要采用FiexedLengthFrameDecoder解码器即可...

以下是服务端代码

 1 package com.ming.netty.nio.stickpack;
 2
 3
 4
 5 import java.net.InetSocketAddress;
 6
 7 import io.netty.bootstrap.ServerBootstrap;
 8 import io.netty.channel.ChannelFuture;
 9 import io.netty.channel.ChannelInitializer;
10 import io.netty.channel.ChannelOption;
11 import io.netty.channel.EventLoopGroup;
12 import io.netty.channel.nio.NioEventLoopGroup;
13 import io.netty.channel.socket.SocketChannel;
14 import io.netty.channel.socket.nio.NioServerSocketChannel;
15 import io.netty.handler.codec.FixedLengthFrameDecoder;
16 import io.netty.handler.codec.string.StringDecoder;
17 import io.netty.handler.logging.LogLevel;
18 import io.netty.handler.logging.LoggingHandler;
19
20 public class EchoServer {
21
22     public void bind(String addr,int port) throws Exception{
23         EventLoopGroup bossGroup=new NioEventLoopGroup();
24         EventLoopGroup workGroup=new NioEventLoopGroup();
25         try {
26             ServerBootstrap server=new ServerBootstrap();
27             server.group(bossGroup,workGroup)
28                   .channel(NioServerSocketChannel.class)
29                   .option(ChannelOption.SO_BACKLOG, 100)
30                   .handler(new LoggingHandler(LogLevel.INFO))
31                   .childHandler(new ChannelInitializer<SocketChannel>() {
32
33                     @Override
34                     protected void initChannel(SocketChannel sc) throws Exception {
35                         sc.pipeline().addLast(new FixedLengthFrameDecoder(50));//FixedLengthFrameDecoder 这个类就是固定长度解码器，意思就是将消息指定长度进行解码
36                         sc.pipeline().addLast(new StringDecoder());
37                         sc.pipeline().addLast(new EchoServerHandler());
38
39                     }
40
41                 });
42             ChannelFuture f=server.bind(new InetSocketAddress(addr, port)).sync();
43             System.out.println("启动服务器:"+f.channel().localAddress());
44             //等等服务器端监听端口关闭
45             f.channel().closeFuture().sync();
46         } catch (Exception e) {
47             e.printStackTrace();
48         }finally{
49             bossGroup.shutdownGracefully();
50             workGroup.shutdownGracefully();
51         }
52     }
53
54
55     public static void main(String[] args) throws Exception{
56         new EchoServer().bind("192.168.1.108", 8500);
57     }
58
59 }

 1 package com.ming.netty.nio.stickpack;
 2
 3 import io.netty.buffer.ByteBuf;
 4 import io.netty.buffer.Unpooled;
 5 import io.netty.channel.ChannelHandlerAdapter;
 6 import io.netty.channel.ChannelHandlerContext;
 7
 8 public class EchoServerHandler extends ChannelHandlerAdapter{
 9
10     int count=0;
11
12     @Override
13     public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
14
15         String body=(String)msg;
16         System.out.println("服务器收到"+(++count)+"次客户端消息，消息是:"+body);
17         body+="$_";
18         ByteBuf rep=Unpooled.copiedBuffer(body.getBytes());
19         ctx.writeAndFlush(rep);
20     }
21
22     @Override
23     public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
24         cause.printStackTrace();
25         ctx.close();
26     }
27
28
29 }

注意: FixedLengthFrameDecoder 这个类解码后，你客户端每次就会按照指定长度进行数据接收了，哈哈...例子中是50个长度的字符哈...

天天学习，天天进步。。。。。。

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