Netty学习02--Netty3服务端

不念不忘少年蓝@ 2023-02-17 11:04 19阅读 0赞

1.netty版本大致版本分为  netty3.x  和  netty4.x、netty5.x

2.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

3、netty服务端hello world案例

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

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  
\}

4、netty客户端hello world案例

channelDisconnected与channelClosed的区别？

1）channelDisconnected只有在连接建立后断开才会调用  
2）channelClosed无论连接是否成功都会调用关闭资源

目录结构：

![20200614093543693.png][]

`5.HelloHandler`

package com.cxb.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);
    	}
    }

6.`Server`

package com.cxb.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
    		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();
    				// 上行时string的解码
    				pipeline.addLast("decoder", new StringDecoder());
    				// 下行时string的编码
    				pipeline.addLast("encoder", new StringEncoder());
    				pipeline.addLast("helloHandler", new HelloHandler());
    				return pipeline;
    			}
    		});
    		
    		bootstrap.bind(new InetSocketAddress(8003));
    		
    		System.out.println("server start!");
    		
    	}
    
    }

7.测试，启动服务端，使用telnet连接服务

![20200613132029430.png][]

发送消息，服务端返回hi

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzMzMzcxNzY2_size_16_color_FFFFFF_t_70][]

![20200613132120728.png][]

附录：项目所需的jar

![20200613132138838.png][]

[代码下载][Link 1]

[20200614093543693.png]: https://img-blog.csdnimg.cn/20200614093543693.png
[20200613132029430.png]: https://img-blog.csdnimg.cn/20200613132029430.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzMzMzcxNzY2_size_16_color_FFFFFF_t_70]: https://img-blog.csdnimg.cn/20200613132055774.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzMzMzcxNzY2,size_16,color_FFFFFF,t_70
[20200613132120728.png]: https://img-blog.csdnimg.cn/20200613132120728.png
[20200613132138838.png]: https://img-blog.csdnimg.cn/20200613132138838.png
[Link 1]: https://github.com/ChenXbFrank/nettyLearnCode