Netty客户端启动

BootStrap

client demo

来源 netty in action

package com.zc.netty.action.demo.time;

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;

public class TimeClient {

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

        String host = "127.0.0.1";// args[0];
        int port = 8080;//Integer.parseInt(args[1]);
        EventLoopGroup workerGroup = new NioEventLoopGroup();

        try {
            Bootstrap b = new Bootstrap(); // (1)
            b.group(workerGroup); // (2)
            b.channel(NioSocketChannel.class); // (3) 设置 channel
            b.option(ChannelOption.SO_KEEPALIVE, true); // (4) 配置通道选项ChannelOption,此处设置连接通道保持连接
            b.handler(new ChannelInitializer<SocketChannel>() {// 我们往往会设置一个 ChannelInitializer抽象类的一个实现类的对象，在这个类的实现方法中我们逐一设置用户定义的各种处理器对象
                @Override
                public void initChannel(SocketChannel ch) throws Exception {
                    ch.pipeline().addLast(new TimeClientHandler());
                }
            });

            // 启动客户端
            ChannelFuture f = b.connect(host, port).sync(); // (5)

            // 等待连接关闭
            f.channel().closeFuture().sync();
        } finally {
            workerGroup.shutdownGracefully();
            System.out.println("over");
            while (true) {

            }
        }
    }
}

客户端启动

- BootStrap客户端启动
- new Bootstrap() 创建客户端对象
- b.channel(NioSocketChannel.class) 设置channel
    - channelFactory(new ReflectiveChannelFactory(channelClass));// 默认创建的 channelFactory是 ReflectiveChannelFactory
        - new ReflectiveChannelFactory(channelClass): 根据传入的NioSocketChannel.class反射创建该实例
        - channelFactory():将上一步创建的ReflectiveChannelFactory设置到BootStrap中并返回Bootstrap用于链式调用
- b.option(ChannelOption.SO_KEEPALIVE, true)
    - 加锁设置属性到bootstrap.options中
- b.handler() 将handler设置到bootstrap中
- b.connect(host, port)
    - connect(InetSocketAddress.createUnresolved(inetHost, inetPort))
        - validate()校验group和channelFactory属性必须配置,校验config.handler必填
        - doResolveAndConnect(remoteAddress, config.localAddress())
            - initAndRegister();// 初始化和注册,返回 ChannelFuture,不会阻塞
                - channelFactory.newChannel();// 创建 socketChannel,如 NioSocketChannel
                    - 构造方法中:
                    - id = newId();// 给每个 channel 分配一个唯一 id
                    - unsafe = newUnsafe();// 每个 channel 内部需要一个 Unsafe 的实例,封装了对 Java 底层 Socket 的操作
                    - pipeline = newChannelPipeline();// 每个 channel 内部都会创建一个 pipeline
                - init(channel) 对 Channel进行初始化设置
                    - channel.pipeline() 获取channel中的pipeline
                    - p.addLast(config.handler()) // 将配置的handler添加到pipeline中
                    - 获取bootstrap.options对象
                    - setChannelOptions(channel, options, logger);// 加锁,将用户配置的选项列表设置到通道对象中
                    - 获取bootstrap.attrs对象
                    - channel.attr((AttributeKey