应用程序代码

官方demo

/*

 * 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 io.netty.example.echo;



import io.netty.bootstrap.Bootstrap;

import io.netty.channel.ChannelFuture;

import io.netty.channel.ChannelInitializer;

import io.netty.channel.ChannelOption;

import io.netty.channel.ChannelPipeline;

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.ssl.SslContext;

import io.netty.handler.ssl.SslContextBuilder;

import io.netty.handler.ssl.util.InsecureTrustManagerFactory;



/**

 * Sends one message when a connection is open and echoes back any received

 * data to the server.  Simply put, the echo client initiates the ping-pong

 * traffic between the echo client and server by sending the first message to

 * the server.

 */

public final class EchoClient {



    static final boolean SSL = System.getProperty("ssl") != null;

    static final String HOST = System.getProperty("host", "127.0.0.1");

    static final int PORT = Integer.parseInt(System.getProperty("port", "8007"));

    static final int SIZE = Integer.parseInt(System.getProperty("size", "256"));



    public static void main(String[] args) throws Exception {

        // Configure SSL.git

        final SslContext sslCtx;

        if (SSL) {

            sslCtx = SslContextBuilder.forClient()

                .trustManager(InsecureTrustManagerFactory.INSTANCE).build();

        } else {

            sslCtx = null;

        }



        // Configure the client.

        EventLoopGroup group = new NioEventLoopGroup();

        try {

            Bootstrap b = new Bootstrap();

            b.group(group)

             .channel(NioSocketChannel.class) //设置通道类 只是设置了通道对象 啥没没做

             .option(ChannelOption.TCP_NODELAY, true)

             .handler(new ChannelInitializer<SocketChannel>() {

                 @Override

                 public void initChannel(SocketChannel ch) throws Exception {

                     ChannelPipeline p = ch.pipeline();

                     if (sslCtx != null) {

                         p.addLast(sslCtx.newHandler(ch.alloc(), HOST, PORT));

                     }

                     //p.addLast(new LoggingHandler(LogLevel.INFO));

                     p.addLast(new EchoClientHandler());

                 }

             });



            // Start the client.

            ChannelFuture f = b.connect(HOST, PORT).sync();



            // Wait until the connection is closed.

            f.channel().closeFuture().sync();

        } finally {

            // Shut down the event loop to terminate all threads.

            group.shutdownGracefully();

        }

    }

}


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netty源码

public abstract class AbstractBootstrap<B extends AbstractBootstrap<B, C>, C extends Channel> implements Cloneable {




/**

     * The {@link Class} which is used to create {@link Channel} instances from.

     * You either use this or {@link #channelFactory(io.netty.channel.ChannelFactory)} if your

     * {@link Channel} implementation has no no-args constructor.

     */

    public B channel(Class<? extends C> channelClass) {

        if (channelClass == null) {

            throw new NullPointerException("channelClass");

        }

        return channelFactory(new ReflectiveChannelFactory<C>(channelClass)); //?

    }


 /**

     * @deprecated Use {@link #channelFactory(io.netty.channel.ChannelFactory)} instead.

     */

    @Deprecated

    public B channelFactory(ChannelFactory<? extends C> channelFactory) {

        if (channelFactory == null) {

            throw new NullPointerException("channelFactory");

        }

        if (this.channelFactory != null) {

            throw new IllegalStateException("channelFactory set already");

        }



        this.channelFactory = channelFactory; //主要是设置通道工厂类

        return self();

    }



@SuppressWarnings("unchecked")

    private B self() {

        return (B) this; //返回值就是启动类本身

    }


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和nio channel区别？

一样 封装了一下nio

通道channel到底指什么?

java网络通信 有2套机制
1.java.net.socket
2.java.nio.channel

相同点 都是表示一个连接 服务器和客户端的连接 但是网络编程里并不真正存在连接这个对象 jdbc里存在连接对象

不同点 首先 1.它们是互相独立的 之间没有任何关系 是java网络通信的2套解决方案 2.1是同步阻塞 2是异步非阻塞 异步非阻塞 可以提高网络通信的性能 就是不要一直卡在那里 等在那里 等就是浪费时间 异步就是连接之间互不影响 自己干自己的事情