Netty入门教程之服务器与客户端案例

netty服务器以及客户端的编写
netty版本大致版本分为 netty3.x 和 netty4.x、netty5.x。这里我们使用netty3.x版本。需要下载相应的jar包导入项目。

首先我们来编写服务器：

Server.java:

package cn.shinelon.server;

import java.net.InetSocketAddress;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

import org.jboss.netty.bootstrap.ServerBootstrap;
import org.jboss.netty.channel.ChannelPipeline;
import org.jboss.netty.channel.ChannelPipelineFactory;
import org.jboss.netty.channel.Channels;
import org.jboss.netty.channel.socket.nio.NioServerSocketChannelFactory;
import org.jboss.netty.handler.codec.string.StringDecoder;
import org.jboss.netty.handler.codec.string.StringEncoder;
/**
* netty官方文档：http://netty.io/3.10/api/index.html
* 服务器
* @author Shinelon
*
*/
public class Server {
public static void main(String[] args) {
//服务类
ServerBootstrap bootStrap=new ServerBootstrap();
//创建两个线程池
ExecutorService boss=Executors.newCachedThreadPool(); //线程池中的线程是client，主要负责端口的监听
ExecutorService worker=Executors.newCachedThreadPool(); //主要负责读写任务

//设置niosocket工厂
bootStrap.setFactory(new NioServerSocketChannelFactory(boss, worker));

//设置管道的工厂
bootStrap.setPipelineFactory(new ChannelPipelineFactory() {

@Override
public ChannelPipeline getPipeline() throws Exception {

ChannelPipeline pipeline=Channels.pipeline();
//解码
pipeline.addLast("decoder", new StringDecoder());
//编码
pipeline.addLast("encoder", new StringEncoder());
pipeline.addLast("helloHandler", new HelloHandler());
return pipeline;
}
});
bootStrap.bind(new InetSocketAddress(10101));
System.out.println("Server Start!!!");
}
}

HelloHandler.java:

package cn.shinelon.server;

import org.jboss.netty.channel.ChannelHandlerContext;
import org.jboss.netty.channel.ChannelStateEvent;
import org.jboss.netty.channel.ExceptionEvent;
import org.jboss.netty.channel.MessageEvent;
import org.jboss.netty.channel.SimpleChannelHandler;

public class HelloHandler extends SimpleChannelHandler {
/**
* channel关闭的时候触发
*/
@Override
public void channelClosed(ChannelHandlerContext ctx, ChannelStateEvent e) throws Exception {
System.out.println("channelClosed");
super.channelClosed(ctx, e);
}

@Override
public void channelConnected(ChannelHandlerContext ctx, ChannelStateEvent e) throws Exception {
System.out.println("channelConnected");
super.channelConnected(ctx, e);
}
/**
* 必须是链接已经建立，关闭通道的时候会触发
*/
@Override
public void channelDisconnected(ChannelHandlerContext ctx, ChannelStateEvent e) throws Exception {
System.out.println("channelDisconnected");
super.channelDisconnected(ctx, e);
}

@Override
public void exceptionCaught(ChannelHandlerContext ctx, ExceptionEvent e) throws Exception {
System.out.println("exceptionCaught");
super.exceptionCaught(ctx, e);
}
/**
* 接收消息
*/
@Override
public void messageReceived(ChannelHandlerContext ctx, MessageEvent e) throws Exception {
String str=(String) e.getMessage();
System.out.println(str);
super.messageReceived(ctx, e);

//回写数据
ctx.getChannel().write("hi");
}

}

上面代码不难，这里需要说明的是ChannelHandler类，我们重写了它的几个方法：

channelConnected：建立新连接，我们通常可以用来检测IP是否是黑名单，比如有人恶意攻击服务器，我们在连接时可以监听发送来的请求，如果请求过于频繁和流量太大就可以将这个IP加入黑名单。

channelDisconnected：链接关闭，可以再用户断线的时候清楚用户的缓存数据等。

messageReceived：接收消息。

接着我们来编写客户端程序：

Client.java:

package cn.shinelon.client;

import java.net.InetSocketAddress;
import java.util.Scanner;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

import org.jboss.netty.bootstrap.ClientBootstrap;
import org.jboss.netty.channel.Channel;
import org.jboss.netty.channel.ChannelFuture;
import org.jboss.netty.channel.ChannelPipeline;
import org.jboss.netty.channel.ChannelPipelineFactory;
import org.jboss.netty.channel.Channels;
import org.jboss.netty.channel.socket.nio.NioClientSocketChannelFactory;
import org.jboss.netty.handler.codec.string.StringDecoder;
import org.jboss.netty.handler.codec.string.StringEncoder;

public class Client {
public static void main(String[] args) throws InterruptedException {
//服务类
ClientBootstrap bootStrap=new ClientBootstrap();
//创建两个线程池
ExecutorService boss=Executors.newCachedThreadPool();
ExecutorService worker=Executors.newCachedThreadPool();
//设置socket工厂
bootStrap.setFactory(new NioClientSocketChannelFactory(boss, worker));
//设置管道工厂
bootStrap.setPipelineFactory(new ChannelPipelineFactory() {

@Override
public ChannelPipeline getPipeline() throws Exception {
ChannelPipeline pipe=Channels.pipeline();
pipe.addLast("decoder", new StringDecoder());
pipe.addLast("encoder",new StringEncoder());
pipe.addLast("hiHandler", new HiHandler());
return pipe;
}
});
//连接服务器
ChannelFuture connect=bootStrap.connect(new InetSocketAddress("127.0.0.1", 10101));
Channel channel=connect.getChannel();
System.out.println("Client Start!!!");
//向服务器发送消息
Scanner scanner=new Scanner(System.in);
while(true) {
Thread.sleep(500);
System.out.println("请输入发送的消息：");
channel.write(scanner.next());
}
}
}

HiHandler.java:

package cn.shinelon.client;

import org.jboss.netty.buffer.ChannelBuffer;
import org.jboss.netty.buffer.ChannelBuffers;
import org.jboss.netty.channel.ChannelHandlerContext;
import org.jboss.netty.channel.ChannelStateEvent;
import org.jboss.netty.channel.ExceptionEvent;
import org.jboss.netty.channel.MessageEvent;
import org.jboss.netty.channel.SimpleChannelHandler;

public class HiHandler extends SimpleChannelHandler {
/**
* channel关闭的时候触发
*/
@Override
public void channelClosed(ChannelHandlerContext ctx, ChannelStateEvent e) throws Exception {
System.out.println("channelClosed");
super.channelClosed(ctx, e);
}

@Override
public void channelConnected(ChannelHandlerContext ctx, ChannelStateEvent e) throws Exception {
System.out.println("channelConnected");
super.channelConnected(ctx, e);
}
/**
* 必须是链接已经建立，关闭通道的时候会触发
*/
@Override
public void channelDisconnected(ChannelHandlerContext ctx, ChannelStateEvent e) throws Exception {
System.out.println("channelDisconnected");
super.channelDisconnected(ctx, e);
}

@Override
public void exceptionCaught(ChannelHandlerContext ctx, ExceptionEvent e) throws Exception {
System.out.println("exceptionCaught");
super.exceptionCaught(ctx, e);
}
/**
* 接收消息
*/
@Override
public void messageReceived(ChannelHandlerContext ctx, MessageEvent e) throws Exception {
String str=(String) e.getMessage();
System.out.println(str);
super.messageReceived(ctx, e);
}
}
注意上面的HiHandler和HelloHandler是一样的，只是修改了一下类名而已。至此，我们已经完成了服务器与客户端的编写，下面我们可以进行测试，当客户端向服务器发送消息后，服务器会向客户端回应“hi”的字符串：