Netty5.0---丢弃服务协议(DiscardServer)

DiscardServer.java

/*
 * Copyright 2012 The Netty Project
 *
 * The Netty Project licenses this file to you under the Apache License,
 * version 2.0 (the "License"); you may not use this file except in compliance
 * with the License. You may obtain a copy of the License at:
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations
 * under the License.
 */
package com.netty.demo.discard;

import io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioServerSocketChannel;

/**
 * Discards any incoming data.
 * 丢弃服务协议，会忽略所有接收数据的协议
 */
public class DiscardServer {

    private final int port;//端口

    
    public DiscardServer(int port) {
        this.port = port;
    }

    public void run() throws Exception {
        EventLoopGroup bossGroup = new NioEventLoopGroup();//老板线程
        EventLoopGroup workerGroup = new NioEventLoopGroup();//员工线程
        try {
        	//创建一个ServerBootstrap实例 ,ServerBootstrap是Netty服务端的启动辅助类，它提供了一系列的方法用于设置服务端启动相关的参数
            ServerBootstrap b = new ServerBootstrap();
            b.group(bossGroup, workerGroup)
             .channel(NioServerSocketChannel.class)
             .childHandler(new ChannelInitializer<SocketChannel>() {
                 @Override
                 public void initChannel(SocketChannel ch) throws Exception {
                	 //业务处理
                     ch.pipeline().addLast(new DiscardServerHandler());
                 }
             });

            // Bind and start to accept incoming connections.
            //绑定和开始接受进来的连接
            ChannelFuture f = b.bind(port).sync();

            // Wait until the server socket is closed.
            // In this example, this does not happen, but you can do that to gracefully
            //丢弃服务协议，什么都不会做
            System.err.println("--------丢弃服务协议--------------");
            // shut down your server//关闭服务
            f.channel().closeFuture().sync();
        } finally {
        	//始终都会执行的代码
            workerGroup.shutdownGracefully();//关闭员工线程
            bossGroup.shutdownGracefully();//关闭老板线程
        }
    }

    public static void main(String[] args) throws Exception {
        int port;
        if (args.length > 0) {
            port = Integer.parseInt(args[0]);
        } else {
            port = 8088;//运行出错，可能是端口被占用
        }
        new DiscardServer(port).run();//启动丢弃服务协议
    }
}

DiscardServerHandler.java

/*
 * Copyright 2012 The Netty Project
 *
 * The Netty Project licenses this file to you under the Apache License,
 * version 2.0 (the "License"); you may not use this file except in compliance
 * with the License. You may obtain a copy of the License at:
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations
 * under the License.
 */
package com.netty.demo.discard;

import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.SimpleChannelInboundHandler;

import java.util.logging.Level;
import java.util.logging.Logger;

/**
 * Handles a server-side channel.
 */
public class DiscardServerHandler extends SimpleChannelInboundHandler<Object> {

	//日志
    private static final Logger logger = Logger.getLogger(DiscardServerHandler.class.getName());

    @Override
    public void messageReceived(ChannelHandlerContext ctx, Object msg) throws Exception {
        // discard
    	logger.info("---------消息接收器---------------");
    }

    @Override
    public void exceptionCaught(ChannelHandlerContext ctx,
            Throwable cause) throws Exception {
        // Close the connection when an exception is raised.
    	//当出现异常的时候，会关闭连接
        logger.log(
                Level.WARNING,
                "Unexpected exception from downstream.",
                cause);
        logger.info("-------出现异常，关闭连接-------------");
        ctx.close();
    }
}

下面是改进过的DiscardServerHandler.java，会相应telnet客户端 

在telnet 里输入什么就在服务端控制台输出什么（单字节输出）

package com.netty.demo.discard;

import io.netty.buffer.ByteBuf;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.SimpleChannelInboundHandler;
import io.netty.util.ReferenceCountUtil;

import java.util.logging.Level;
import java.util.logging.Logger;

/**
 * Handles a server-side channel.
 */
public class DiscardServerHandler extends SimpleChannelInboundHandler<Object> {

	//日志
    private static final Logger logger = Logger.getLogger(DiscardServerHandler.class.getName());

    @Override
    public void messageReceived(ChannelHandlerContext ctx, Object msg) throws Exception {
        // discard
    	
    	//自己改动过的，官网例子的这个方法没有任何东西的
    	logger.info("---------消息接收器---------------");
    	ByteBuf in=(ByteBuf) msg;
    	try {
			while(in.isReadable()){
				System.out.println("--yy--"+(char)in.readByte());
				System.out.flush();
			}
		} catch (Exception e) {
			// TODO Auto-generated catch block
			/**
			 * 在netty5.0版本，不需要释放资源,框架已经自动帮我们释放,
			 * 如果再加ReferenceCountUtil.release(msg)这句代码，运行就回报错
			 */
			//ReferenceCountUtil.release(msg);
			e.printStackTrace();
		}
    }

    @Override
    public void exceptionCaught(ChannelHandlerContext ctx,
            Throwable cause) throws Exception {
        // Close the connection when an exception is raised.
    	//当出现异常的时候，会关闭连接
        logger.log(
                Level.WARNING,
                "Unexpected exception from downstream.",
                cause);
        logger.info("-------出现异常，关闭连接-------------");
        ctx.close();
    }
}

运行效果图：