[自己做个游戏服务器二] 游戏服务器的基石-Netty全解析，有例子，多图解释

public abstract class MultithreadEventLoopGroup extends MultithreadEventExecutorGroup implements EventLoopGroup {
   private static final InternalLogger logger = InternalLoggerFactory.getInstance(MultithreadEventLoopGroup.class);
   private static final int DEFAULT_EVENT_LOOP_THREADS = Math.max(1, SystemPropertyUtil.getInt("io.netty.eventLoopThreads", NettyRuntime.availableProcessors() * 2));
   protected MultithreadEventLoopGroup(int nThreads, Executor executor, Object... args) {
       super(nThreads == 0 ? DEFAULT_EVENT_LOOP_THREADS : nThreads, executor, args);
  }
复制代码

ChannelPipeline p = ...;
  p.addLast("1", new InboundHandlerA());
  p.addLast("2", new InboundHandlerB());
  p.addLast("3", new OutboundHandlerA());
  p.addLast("4", new OutboundHandlerB());
  p.addLast("5", new InboundOutboundHandlerX());
复制代码

package com.xiangcai;
import io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelOption;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.nio.NioServerSocketChannel;
/**
* 服务端代码
* @author 香菜
*/
public class GameServer {
   /**
    * 启动
    */
   public static void start() throws InterruptedException {
       EventLoopGroup boss = new NioEventLoopGroup(1);
       EventLoopGroup worker = new NioEventLoopGroup();
       try {
           ServerBootstrap serverBootstrap = new ServerBootstrap();
           serverBootstrap.group(boss, worker)
                  .channel(NioServerSocketChannel.class)
                   //服务端可连接队列数,对应TCP/IP协议listen函数中backlog参数
                  .option(ChannelOption.SO_BACKLOG, 1024)
                   //设置TCP长连接,一般如果两个小时内没有数据的通信时,TCP会自动发送一个活动探测数据报文
                  .childOption(ChannelOption.SO_KEEPALIVE, true)
                   //将小的数据包包装成更大的帧进行传送，提高网络的负载,即TCP延迟传输
                  .childOption(ChannelOption.TCP_NODELAY, true)
                  .childHandler(new NettyServerHandlerInitializer());
           ChannelFuture channelFuture = serverBootstrap.bind(8088).sync();
           System.out.println("服务器启动了");
           channelFuture.channel().closeFuture().sync();
      } finally {
           // 关闭线程
           boss.shutdownGracefully();
           worker.shutdownGracefully();
      }
  }
   public static void main(String[] args) throws InterruptedException {
       start();
  }
}
复制代码

package com.xiangcai;
import io.netty.channel.Channel;
import io.netty.channel.ChannelInitializer;
import io.netty.handler.codec.LineBasedFrameDecoder;
import io.netty.handler.codec.string.StringDecoder;
/**
* 服务端代码
* @author 香菜
*/
public class NettyServerHandlerInitializer extends ChannelInitializer<Channel> {
   @Override
   protected void initChannel(Channel ch) throws Exception {
       ch.pipeline()
               //基于换行符的解码器
              .addLast(new LineBasedFrameDecoder(1024))
               // 强转字符串
              .addLast(new StringDecoder())
               // 业务处理
              .addLast(new NettyServerHandler());
  }
}
复制代码

package com.xiangcai;
import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandlerAdapter;
import io.netty.handler.timeout.IdleState;
import io.netty.handler.timeout.IdleStateEvent;
/**
* 服务端代码
* @author 香菜
*/
public class NettyServerHandler extends ChannelInboundHandlerAdapter {
   @Override
   public void channelActive(ChannelHandlerContext ctx) throws Exception {
       super.channelActive(ctx);
  }
   /**
    * 超时处理 如果5秒没有接受客户端的心跳，就触发; 如果超过两次，则直接关闭;
    */
   @Override
   public void userEventTriggered(ChannelHandlerContext ctx, Object obj) throws Exception {
       if (obj instanceof IdleStateEvent) {
           IdleStateEvent event = (IdleStateEvent) obj;
           if (IdleState.READER_IDLE.equals(event.state())) { // 如果读通道处于空闲状态，说明没有接收到心跳命令
               System.out.println("已经5秒没有接收到客户端的信息了");
          }
      } else {
           super.userEventTriggered(ctx, obj);
      }
  }
   /**
    * 业务逻辑处理
    */
   @Override
   public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
       System.out.println("服务端收到信息：" + msg);
       String respStr = "收到了 " + System.getProperty("line.separator");
       ByteBuf resp = Unpooled.copiedBuffer(respStr.getBytes());
       ctx.writeAndFlush(resp);
  }
   /**
    * 异常处理
    */
   @Override
   public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
       cause.printStackTrace();
       ctx.close();
  }
}
复制代码

package com.xiangcai;
import io.netty.bootstrap.Bootstrap;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelOption;
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.LineBasedFrameDecoder;
import io.netty.handler.codec.string.StringDecoder;
import org.junit.Test;
/**
* 服务端代码
* @author 香菜
*/
public class TestClient {
   public static void clientStart() {
       EventLoopGroup group = new NioEventLoopGroup();
       try {
           Bootstrap b = new Bootstrap();
           b.group(group)
                  .channel(NioSocketChannel.class)
                  .option(ChannelOption.TCP_NODELAY, true)
                  .handler(new ChannelInitializer<SocketChannel>() {
                       protected void initChannel(SocketChannel ch) throws Exception {
                           ch.pipeline().addLast(new LineBasedFrameDecoder(1024));
                           ch.pipeline().addLast(new StringDecoder());
                           ch.pipeline().addLast(new ClientHandler());
                      };
                  });
           // 发起异步连接操作
           ChannelFuture f = b.connect("127.0.0.1", 8088).sync();
           // 等待客户端连接关闭
           f.channel().closeFuture().sync();
      } catch (InterruptedException e) {
           e.printStackTrace();
      } finally {
           // 优雅退出，释放NIO线程组
           group.shutdownGracefully();
      }
  }
   public static void main(String[] args) {
       clientStart();
  }
}
复制代码

package com.xiangcai;
import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandlerAdapter;
import java.nio.charset.StandardCharsets;
/**
* 服务端代码
* @author 香菜
*/
public class ClientHandler extends ChannelInboundHandlerAdapter {
  @Override
  public void channelActive(ChannelHandlerContext ctx) {
      System.out.println("建立连接");
      byte[] bytes = ("连接上了，开始说话" + System.getProperty("line.separator")).getBytes(StandardCharsets.UTF_8);
      ByteBuf message = Unpooled.buffer(bytes.length);
      message.writeBytes(bytes);
      ctx.writeAndFlush(message);
  }
  @Override
  public void channelRead(ChannelHandlerContext ctx, Object msg) {
      String body = (String) msg;
      System.out.println("收到信息 " + body);
  }
  @Override
  public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) {
      System.out.println("发生异常");
      ctx.close();
  }
}
复制代码