Netty5 案例讲解

小灰灰 2021-12-14 21:13 283阅读 0赞

## Netty5 案例讲解 ##

*  分布式框架中通常使用Netty3.x
 *  游戏服务器通常使用Netty4.x、Netty5.x(4、5相差不多，与3相差比较大)
 *  Netty5使用对象池取代线程池

## 服务端 ##

public class Server {
    
       public static void main(String[] args) {
          //服务类
          ServerBootstrap bootstrap = new ServerBootstrap();
          //boss和worker
          EventLoopGroup boss = new NioEventLoopGroup();
          EventLoopGroup worker = new NioEventLoopGroup();
      
      try {
         //设置线程池
         bootstrap.group(boss, worker);
         
         //设置socket工厂、
         bootstrap.channel(NioServerSocketChannel.class);
         
         //设置管道工厂
         bootstrap.childHandler(new ChannelInitializer<Channel>() {
    
            @Override
            protected void initChannel(Channel ch) throws Exception {
               ch.pipeline().addLast(new StringDecoder());
               ch.pipeline().addLast(new StringEncoder());
               //管道绑定消息处理器
               ch.pipeline().addLast(new ServerHandler());
            }
         });
         
         //netty3中对应设置如下
         //bootstrap.setOption("backlog", 1024);
         //bootstrap.setOption("tcpNoDelay", true);
         //bootstrap.setOption("keepAlive", true);
         //设置参数，TCP参数
         bootstrap.option(ChannelOption.SO_BACKLOG, 2048);//serverSocketchannel的设置，链接缓冲池的大小
         bootstrap.childOption(ChannelOption.SO_KEEPALIVE, true);//socketchannel的设置,维持链接的活跃，清除死链接
         bootstrap.childOption(ChannelOption.TCP_NODELAY, true);//socketchannel的设置,关闭延迟发送
         
         //绑定端口
         ChannelFuture future = bootstrap.bind(10101);
         
         System.out.println("start");
         
         //等待服务端关闭
         future.channel().closeFuture().sync();
         
      } catch (Exception e) {
         e.printStackTrace();
      } finally{
         //释放资源
         boss.shutdownGracefully();
         worker.shutdownGracefully();
      }
    
    
     }
    }

## 客户端 ##

public class Client {
    
    public static void main(String[] args) {
    	//服务类
    	Bootstrap bootstrap = new Bootstrap();
    	//worker
    	EventLoopGroup worker = new NioEventLoopGroup();
    	
    	try {
    		//设置线程池
    		bootstrap.group(worker);
    		
    		//设置socket工厂、
    		bootstrap.channel(NioSocketChannel.class);
    		
    		//设置管道
    		bootstrap.handler(new ChannelInitializer<Channel>() {
    
    			@Override
    			protected void initChannel(Channel ch) throws Exception {
    				ch.pipeline().addLast(new StringDecoder());
    				ch.pipeline().addLast(new StringEncoder());
    				ch.pipeline().addLast(new ClientHandler());
    			}
    		});
    		
    		ChannelFuture connect = bootstrap.connect("127.0.0.1", 10101);
    		
    		BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(System.in));
    		while(true){
    			System.out.println("请输入：");
    			String msg = bufferedReader.readLine();
    			connect.channel().writeAndFlush(msg);
    		}
    		
    	} catch (Exception e) {
    		 e.printStackTrace();
    	} finally{
    		worker.shutdownGracefully();
    	}
    }
    }

**单客户端多连接（两种方式）**

*  使用对象池实现多连接（当线程不安全，会产生阻塞时，采用对象池的方法）
 *  使用对象组实现多连接（当线程安全，不会产生阻塞时，采用对象组的方法）

在Netty中是线程安全的，所以使用使用对象组的方式实现多连接（线程池中线程是安全，并且任务是串行化执行的）

public class MultClient {
       
       /**
        * 服务类
        */
       private Bootstrap bootstrap = new Bootstrap();
       
       /**
        * 会话
        */
       private List<Channel> channels = new ArrayList<>();
       
       /**
        * 引用计数
        */
       private final AtomicInteger index = new AtomicInteger();
       
       /**
        * 初始化
        * @param count
        */
       public void init(int count){
      
      //worker
      EventLoopGroup worker = new NioEventLoopGroup();
      
      //设置线程池
      bootstrap.group(worker);
      
      //设置socket工厂、
      bootstrap.channel(NioSocketChannel.class);
      
      //设置管道
      bootstrap.handler(new ChannelInitializer<Channel>() {
    
         @Override
         protected void initChannel(Channel ch) throws Exception {
            ch.pipeline().addLast(new StringDecoder());
            ch.pipeline().addLast(new StringEncoder());
            //这里要绑定消息处理封装类
            ch.pipeline().addLast(new ClientHandler());
         }
      });
      //模拟同时连接多个
      for(int i=1; i<=count; i++){
         ChannelFuture future = bootstrap.connect("192.168.0.103", 10101);
         channels.add(future.channel());
      }
       }
       
       /**
        * 获取会话
        * @return
        */
       public Channel nextChannel(){
          return getFirstActiveChannel(0);
       }
       
       
       private Channel getFirstActiveChannel(int count){
          Channel channel = channels.get(Math.abs(index.getAndIncrement() % channels.size()));
          if(!channel.isActive()){
             //重连
             reconnect(channel);
             if(count >= channels.size()){
                throw new RuntimeException("no can use channel");
             }
             return getFirstActiveChannel(count + 1);
          }
          return channel;
       }
       
       /**
        * 重连
        * @param channel
        */
       private void reconnect(Channel channel){
          synchronized(channel){
             if(channels.indexOf(channel) == -1){
                return ;
             }
             
             Channel newChannel = bootstrap.connect("192.168.0.103", 10101).channel();
             channels.set(channels.indexOf(channel), newChannel);
          }
       }
    
    }

**启动函数**

public class Start {
    
       public static void main(String[] args) {
    
      MultClient client = new MultClient();
      client.init(5);
      
      BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(System.in));
      while(true){
         try {
            System.out.println("请输入:");
            String msg = bufferedReader.readLine();
            client.nextChannel().writeAndFlush(msg);
         } catch (Exception e) {
            e.printStackTrace();
         }
      }
       }
    
    }

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