Netty入门（三）——服务端与客户端案例netty3.x

约定不等于承诺〃 2022-05-22 11:47 329阅读 0赞

**一、netty可以运用在那些领域**

1分布式进程通信  
例如: hadoop、dubbo、akka等具有分布式功能的框架，底层RPC通信都是基于netty实现的，这些框架使用的版本通常都还在用netty3.x  
2、游戏服务器开发  
最新的游戏服务器有部分公司可能已经开始采用netty4.x 或 netty5.x  
  
**二、服务端与客户端代码案例(这里是netty3x跟最新写法有点区别，但原理一样)**

**1.netty服务端hello world案例**

代码如下：

HelloHandler.java

package com.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;
    /**
     * 消息接受处理类
     *
     */
    public class HelloHandler extends SimpleChannelHandler {
    
    	/**
    	 * 接收消息
    	 */
    	@Override
    	public void messageReceived(ChannelHandlerContext ctx, MessageEvent e) throws Exception {
    
    		
    		String s = (String) e.getMessage();
    		System.out.println(s);
    		
    		//回写数据
    		ctx.getChannel().write("hi");
    		super.messageReceived(ctx, e);
    	}
    
    	/**
    	 * 捕获异常
    	 */
    	@Override
    	public void exceptionCaught(ChannelHandlerContext ctx, ExceptionEvent e) throws Exception {
    		System.out.println("exceptionCaught");
    		super.exceptionCaught(ctx, e);
    	}
    
    	/**
    	 * 新连接
    	 */
    	@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，关闭通道的时候才会触发
    	 */
    	@Override
    	public void channelDisconnected(ChannelHandlerContext ctx, ChannelStateEvent e) throws Exception {
    		System.out.println("channelDisconnected");
    		super.channelDisconnected(ctx, e);
    	}
    
    	/**
    	 * 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);
    	}
    }

Server.java

package com.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服务端入门
     *
     */
    public class Server {
    
    	public static void main(String[] args) {
    
    		//服务类
    		ServerBootstrap bootstrap = new ServerBootstrap();
    		
    		//boss线程监听端口，worker线程负责数据读写  他们里面都会负责一个selector。
    		ExecutorService boss = Executors.newCachedThreadPool();
    		ExecutorService worker = Executors.newCachedThreadPool();
    		
    		//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();
    				pipeline.addLast("decoder", new StringDecoder());
    				pipeline.addLast("encoder", new StringEncoder());
    				pipeline.addLast("helloHandler", new HelloHandler());
    				return pipeline;
    			}
    		});
    		
    		bootstrap.bind(new InetSocketAddress(10101));
    		
    		System.out.println("start!!!");
    		
    	}
    
    }

部分事件如下：

SimpleChannelHandler 处理消息接收和写

\{  
messageReceived接收消息  
channelConnected新连接，通常用来检测IP是否是黑名单,非法攻击，恶意访问检测等等  
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  
\}  
  
**2、netty客户端hello world案例**

HiHandler.java

package com.client;
    
    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;
    /**
     * 消息接受处理类
     *
     */
    public class HiHandler extends SimpleChannelHandler {
    
    	/**
    	 * 接收消息
    	 */
    	@Override
    	public void messageReceived(ChannelHandlerContext ctx, MessageEvent e) throws Exception {
    
    		
    		String s = (String) e.getMessage();
    		System.out.println(s);
    		
    		super.messageReceived(ctx, e);
    	}
    
    	/**
    	 * 捕获异常
    	 */
    	@Override
    	public void exceptionCaught(ChannelHandlerContext ctx, ExceptionEvent e) throws Exception {
    		System.out.println("exceptionCaught");
    		super.exceptionCaught(ctx, e);
    	}
    
    	/**
    	 * 新连接
    	 */
    	@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，关闭通道的时候才会触发
    	 */
    	@Override
    	public void channelDisconnected(ChannelHandlerContext ctx, ChannelStateEvent e) throws Exception {
    		System.out.println("channelDisconnected");
    		super.channelDisconnected(ctx, e);
    	}
    
    	/**
    	 * 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);
    	}
    }

Client.java

package com.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;
    /**
     * netty客户端入门
     *
     */
    public class Client {
    
    	public static void main(String[] args) {
    		
    		//服务类
    		ClientBootstrap bootstrap = new  ClientBootstrap();
    		
    		//线程池
    		ExecutorService boss = Executors.newCachedThreadPool();  //
    		ExecutorService worker = Executors.newCachedThreadPool();  //
    		
    		//socket工厂
    		bootstrap.setFactory(new NioClientSocketChannelFactory(boss, worker));
    		
    		//管道工厂
    		bootstrap.setPipelineFactory(new ChannelPipelineFactory() {
    			
    			@Override
    			public ChannelPipeline getPipeline() throws Exception {
    				ChannelPipeline pipeline = Channels.pipeline();
    				pipeline.addLast("decoder", new StringDecoder());
    				pipeline.addLast("encoder", new StringEncoder());
    				pipeline.addLast("hiHandler", new HiHandler());
    				return pipeline;
    			}
    		});
    		
    		//连接服务端  可以创建多个客户端连接
    		ChannelFuture connect = bootstrap.connect(new InetSocketAddress("127.0.0.1", 10101));
    		Channel channel = connect.getChannel();
    		
    		System.out.println("client start");
    		
    		Scanner scanner = new Scanner(System.in);
    		while(true){
    			System.out.println("请输入");
    			channel.write(scanner.next());
    		}
    	}
    
    }

channelDisconnected与channelClosed的区别：  
channelDisconnected只有在连接建立后断开才会调用

channelClosed无论连接是否成功都会调用关闭资源

[Netty入门（三）——服务端与客户端案例netty5.x][Netty_netty5.x]

[Netty_netty5.x]: https://blog.csdn.net/gududedabai/article/details/80799745