Netty学习笔记(二) 实现服务端和客户端

在Netty学习笔记(一) 实现DISCARD服务中,我们使用Netty和Python实现了简单的丢弃DISCARD服务,这篇,我们使用Netty实现服务端和客户端交互的需求。

前置工作

开发环境

  • JDK8
  • Netty版本:5.0.0.Alpha2
  • 集成环境:IDEA
  • 构建工具:Gradle

依赖

    compile group: 'io.netty', name: 'netty-all', version: '5.0.0.Alpha2'
compile group: 'org.projectlombok', name: 'lombok', version: '1.18.0'

服务端

Netty服务器主要由两部分组成:

  • 配置服务器功能,如线程、端口
  • 实现服务器处理程序

服务端HandleAdapter

我们是首先实现服务端处理程序,实现Handle要求继承HandleAdapter,这里我们继承SimpleChannelInboundHandler<T>,下面是具体实现的代码信息,其每个函数的作用,我们只需要重写我们所需要的方法即可。


import io.netty.channel.ChannelHandler;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.SimpleChannelInboundHandler; /**
* Netty 服务Handle
*
* @author tao
*/
@ChannelHandler.Sharable
public class EchoServiceHandle extends SimpleChannelInboundHandler<String> { /**
* 接收到新的消息
* @param ctx
* @param msg
* @throws Exception
*/
@Override
public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
// 打印接收到的消息
System.out.println("Netty服务端接收到消息 " + msg);
// 回复消息
ctx.channel().writeAndFlush("Send ----> 客户端" + ctx.channel().id() + "你好,我已经接收到你发送的消息");
} /**
* 有新的连接加入
* @param ctx
* @throws Exception
*/
@Override
public void channelActive(ChannelHandlerContext ctx) throws Exception {
System.out.println("接入新的Channel,id = " + ctx.channel().id());
} /**
* 服务端发生异常信息的时候
* @param ctx
* @param cause
*/
@Override
public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) {
// 服务端发生异常
System.out.println("Netty 服务端发生异常 ,异常信息:" + cause);
ctx.close();
} @Override
protected void messageReceived(ChannelHandlerContext ctx, String msg) {}
}

服务端启动

在服务端的EchoServiceHandle完成之后,我们需要配置服务器的参数信息,比如端口等


import io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.*;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioServerSocketChannel;
import io.netty.handler.codec.string.StringDecoder;
import io.netty.handler.codec.string.StringEncoder;
import lombok.Data; /**
* @author tao
*/
@Data
public class EchoService { private int port; public void start() throws Exception {
EventLoopGroup boosGroup = new NioEventLoopGroup();
EventLoopGroup workGroup = new NioEventLoopGroup();
try {
ServerBootstrap bootstrap = new ServerBootstrap();
bootstrap
.group(boosGroup, workGroup)
.channel(NioServerSocketChannel.class)
.option(ChannelOption.SO_BACKLOG, 128)
.childHandler(
new ChannelInitializer<SocketChannel>() {
@Override
protected void initChannel(SocketChannel ch) throws Exception {
ChannelPipeline pipeline = ch.pipeline();
//字符串解码器
pipeline.addLast(new StringDecoder());
//字符串编码器
pipeline.addLast(new StringEncoder());
//服务端处理器
pipeline.addLast(new EchoServiceHandle());
}
});
ChannelFuture sync = bootstrap.bind(port).sync();
System.out.println("Netty Service start with " + port + "...");
sync.channel().closeFuture().sync();
} finally {
workGroup.shutdownGracefully();
boosGroup.shutdownGracefully();
}
} public static void main(String[] args) throws Exception {
EchoService service = new EchoService();
service.setPort(8080);
service.start();
}
}

启动后,我们可以看到启动信息如下:

Netty Service start with 8080...

客户端

客户端和服务端类似,可以相互参考学习.

客户端HandleAdapter

import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelHandler;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.SimpleChannelInboundHandler;
import io.netty.util.CharsetUtil; @ChannelHandler.Sharable
public class EchoClientHandle extends SimpleChannelInboundHandler<String> { /**
* 连接创建成功的时候
* @param ctx
* @throws Exception
*/
@Override
public void channelActive(ChannelHandlerContext ctx) throws Exception {
System.out.println("channelActive");
//连接成功后向服务端发送问候消息
ctx.channel().writeAndFlush(Unpooled.copiedBuffer("你好,这里是Netty客户端", CharsetUtil.UTF_8));
} /**
* 发生异常
* @param ctx
* @param cause
*/
@Override
public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) {
System.out.println("exceptionCaught");
cause.printStackTrace();
ctx.close();
} /**
* 接收到服务端发过来的数据
* @param ctx
* @param msg
*/
@Override
public void channelRead(ChannelHandlerContext ctx, Object msg) {
//打印接收到的数据信息
System.out.println("channelRead = " + msg);
} @Override
protected void messageReceived(ChannelHandlerContext ctx, String msg) {}
}

客户端启动

import io.netty.bootstrap.Bootstrap;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelPipeline;
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.string.StringDecoder;
import io.netty.handler.codec.string.StringEncoder;
import lombok.Data;
import lombok.experimental.Accessors;
import lombok.extern.slf4j.Slf4j; import java.net.InetSocketAddress; /** @author tao */
@Data
@Accessors(chain = true)
@Slf4j
public class EchoClient { private int port; private String host; public void start() throws Exception {
EventLoopGroup group = new NioEventLoopGroup();
try {
Bootstrap bootstrap = new Bootstrap();
bootstrap
.group(group)
.channel(NioSocketChannel.class)
.handler(
new ChannelInitializer<SocketChannel>() {
@Override
protected void initChannel(SocketChannel ch) throws Exception {
ChannelPipeline pipeline = ch.pipeline();
// 字符串解码器
pipeline.addLast(new StringDecoder());
// 字符串编码器
pipeline.addLast(new StringEncoder()); pipeline.addLast(new EchoClientHandle());
}
});
ChannelFuture sync = bootstrap.connect(new InetSocketAddress(host, port)).sync();
sync.channel().closeFuture().sync(); } catch (Exception e) {
e.printStackTrace();
} finally {
group.shutdownGracefully().sync();
}
} public static void main(String[] args) throws Exception {
EchoClient client = new EchoClient();
client.setHost("127.0.0.1").setPort(8080);
client.start();
}
}

效果

服务端效果

   Netty Service start with 8080...
接入新的Channel,id = c0d4f037
Netty服务端接收到消息 你好,这里是Netty客户端

客户端效果

channelActive
channelRead = Send ----> 客户端c0d4f037你好,我已经接收到你发送的消息
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