Netty分隔符和定长解码器使用

public void bind(int port) throws Exception {

// 配置服务端的NIO线程组

// 服务端接受客户端的连接

NioEventLoopGroup bossGroup = new NioEventLoopGroup();

// 进行SocketChannel的网络读写

NioEventLoopGroup workerGroup = new NioEventLoopGroup();

try {

ServerBootstrap b = new ServerBootstrap();

b.group(bossGroup, workerGroup).channel(NioServerSocketChannel.class)

.option(ChannelOption.SO_BACKLOG, 100)

.handler(new LoggingHandler(LogLevel.INFO))

.childHandler(new ChannelInitializer<SocketChannel>() {

@Override

protected void initChannel(SocketChannel ch) throws Exception {

// 1.定义分隔符

ByteBuf delimiter = Unpooled.copiedBuffer("$_".getBytes());

// 2.添加分隔符解码器 单条消息最大长度1024，

// 当到达长度后仍然没有查找到分隔符，就抛TooLongFrameException

// 第二个参数是分隔符缓冲对象

ch.pipeline().addLast(new DelimiterBasedFrameDecoder(1024, delimiter));

// 3.添加字符串处理解码器

ch.pipeline().addLast(new StringDecoder());

// 4.添加自定义的处理器

ch.pipeline().addLast(new EchoServerHandler());

}

});

// 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

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){

// 采用默认值

}

}

new EchoServer().bind(port);

}

}

EchoServerHandler

package com.dpb.netty.demo3;

import io.netty.buffer.ByteBuf;

import io.netty.buffer.Unpooled;

import io.netty.channel.ChannelHandlerAdapter;

import io.netty.channel.ChannelHandlerContext;

/**

• DelimiterBasedFrameDecoder 案例

• 自定义处理器

• @author 波波烤鸭

*/

public class EchoServerHandler extends ChannelHandlerAdapter{

// 统计接收消息的数量

private int counter;

@Override

public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {

// 获取客户端传递的消息

String body = (String) msg;

// 打印消息

System.out.println("This is "+ ++counter + " times receive client ：["+body+"]");

// 分隔符已经被截取掉了，响应信息的时候我们需要再加上分隔符

body += "$_";

ByteBuf echo = Unpooled.copiedBuffer(body.getBytes());

ctx.writeAndFlush(echo);

}

@Override

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

cause.printStackTrace();

ctx.close(); // 发生异常关闭链路

}

}

[](()客户断

---

EchoClient

package com.dpb.netty.demo3;

import io.netty.bootstrap.Bootstrap;

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.NioSocketChannel;

import io.netty.handler.codec.DelimiterBasedFrameDecoder;

import io.netty.handler.codec.string.StringDecoder;

/**

• DelimiterBasedFrameDecoder 案例 客户端

• @author 波波烤鸭

*/

public class EchoClient {

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) {

// 采用默认值

}

}

new EchoClient().connector(port, "127.0.0.1");

}

public void connector(int port, String host) throws Exception {

// 配置客户端NIO线程组

EventLoopGroup group = new NioEventLoopGroup();

try {

Bootstrap b = new Bootstrap();

b.group(group).channel(NioSocketChannel.class)

.option(ChannelOption.TCP_NODELAY, true)

.handler(new ChannelInitializer<SocketChannel>() {

@Override

protected void initChannel(SocketChannel ch) throws Exception {

// TODO Auto-generated method stub

// 1.定义分隔符

ByteBuf delimiter = Unpooled.copiedBuffer("$_".getBytes());

// 2.添加分隔符解码器

ch.pipeline().addLast(new DelimiterBasedFrameDecoder(1024, delimiter));

// 3.添加字符串处理解码器

ch.pipeline().addLast(new StringDecoder());

// 4.添加自定义的处理器

ch.pipeline().addLast(new EchoClientHandler());

}

});

// 发起异步连接操作

ChannelFuture f = b.connect(host, port).sync();

// 等待客户端链路关闭

f.channel().closeFuture().sync();

} finally {

// 优雅退出，释放NIO线程组

group.shutdownGracefully();

}

}

}

EchoClientHandler

package com.dpb.netty.demo3;

import io.netty.buffer.Unpooled;

import io.netty.channel.ChannelHandlerAdapter;

import io.netty.channel.ChannelHandlerContext;

/**

• DelimiterBasedFrameDecoder 案例

• 自定义客户端处理器

• @author 波波烤鸭

*/

public class EchoClientHandler extends ChannelHandlerAdapter{

private int counter;

static final String ECHOREQ = "Hi , bobo烤鸭. Welcome to Netty.$";

public EchoClientHandler(){

}

@Override

public void channelActive(ChannelHandlerContext ctx) throws Exception {

// TODO Auto-generated method stub

for (int i = 0; i < 10; i++) {

// 发送消息别立马刷新

ctx.writeAndFlush(Unpooled.copiedBuffer(ECHO_REQ.getBytes()));

}

}

@Override

public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {

// TODO Auto-generated method stub

System.out.println("This is "+ ++counter + "time recevice server ：【"+msg+"】");

}

@Override

public void channelReadComplete(ChannelHandlerContext ctx) throws Exception {

// TODO Auto-generated method stub

ctx.flush();

}

@Override

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

// TODO Auto-generated method stub

cause.printStackTrace();

ctx.close();

}

}

[](()测试

---

服务端运行结果

客户端运行结果

服务端成功接收到了客户端发送的10条信息，客户端成功接收到了服务端返回的10条信息，测试结果表明使用DelimiterBasedFrameDecoder可以自动对采用分隔符做码流结束标识的消息进行解码。运行多次的原因是模拟TCP粘包/拆包，如果没有DelimiterBasedFrameDecoder解码处理，服务端和客户端都将运行失败，如下:

输出结果:

This is 1 times receive client ：

[Hi , bobo烤鸭. Welcome to Netty.$_Hi ,

bobo烤鸭. Welcome to Netty.$_Hi ,

bobo烤鸭. Welcome to Netty.$_Hi ,

bobo烤鸭. Welcome to Netty.$_Hi ,

bobo烤鸭. Welcome to Netty.$_Hi ,

bobo烤鸭. Welcome to Netty.$_Hi ,

bobo烤鸭. Welcome to Netty.$_Hi ,

bobo烤鸭. Welcome to Netty.$_Hi ,

bobo烤鸭. Welcome to Netty.$_Hi ,

bobo烤鸭. Welcome to Netty.$_]

客户端发送的10条信息，在服务端粘包成一条信息了。那么响应信息肯定也是一条了。

[](()FixedLengthFrameDecoder