Netty解码器之DelimiterBasedFrameDecoder_netty delimiterbasedframedecoder-优快云博客

本文介绍了Netty的DelimiterBasedFrameDecoder解码器，该解码器用于处理以特定分隔符标记消息边界的场景。通过实例代码展示了其在消息解码中的应用。

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1.认识DelimiterBasedFrameDecoder,通过对DelimiterBasedFrameDecoder的使用，我们可以自动完成以分隔符作为码流结束标识的消息的解码。

下面通过代码来看DelimiterBasedFrameDecoder的作用

package netty.server;

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;
import io.netty.handler.logging.LogLevel;
import io.netty.handler.logging.LoggingHandler;
import netty.handler.EchoServerHandler;

/**
 * Created by LeoLei on 2017/3/20.
 * mail : lei.peichen@gmail.com
 */
public class EchoServer {
    public void bind(int port) throws Exception{
        EventLoopGroup bossgroup = new NioEventLoopGroup();
        EventLoopGroup workerGroup = new NioEventLoopGroup();

        try {
            ServerBootstrap serverBootstrap = new ServerBootstrap();
            serverBootstrap.group(bossgroup,workerGroup).channel(NioServerSocketChannel.class).option(ChannelOption.SO_BACKLOG,100).handler(new LoggingHandler(LogLevel.INFO)).childHandler(new ChannelInitializer() {
                protected void initChannel(SocketChannel ch) throws Exception {
                    ByteBuf delimiter = Unpooled.copiedBuffer("$_".getBytes());
                    ch.pipeline().addLast(new DelimiterBasedFrameDecoder(1024,delimiter));
                    ch.pipeline().addLast(new StringDecoder());
                    ch.pipeline().addLast(new EchoServerHandler());
                }
            });
            //绑定端口，同步等待成功
            ChannelFuture f = serverBootstrap.bind(port).sync();
            //等待服务器监听端口关闭
            f.channel().closeFuture().sync();
        }finally {
            //优雅退出，释放线程池资源
            bossgroup.shutdownGracefully();
            workerGroup.shutdownGracefully();
        }
    }

    public static void main(String[] args) throws Exception{
        int port = 8080;
        if(args != null && args.length > 0){
            try {
                port = Integer.valueOf(args[0]);
            }catch (NumberFormatException e){
                e.printStackTrace();
            }
        }
        new EchoServer().bind(port);
    }
}

package netty.handler;

import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelHandler;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.SimpleChannelInboundHandler;

/**
 * Created by LeoLei on 2017/3/20.
 * mail : lei.peichen@gmail.com
 */
@ChannelHandler.Sharable
public class EchoServerHandler extends SimpleChannelInboundHandler