搭建生产级的Netty项目

Netty是Trustin Lee在2004年开发的一款高性能的网络应用程序框架。相比于JDK自带的NIO，Netty作了至关多的加强，且隔离了jdk nio的实现细节，API也比较友好，还支持流量整形等高级特性。在咱们常见的一些开源项目中已经广泛的应用到了Netty，好比Dubbo、Elasticsearch、Zookeeper等。

Netty的具体开发
提示：因代码相对较多，这里只展现其主要部分，至于项目中用到的编解码器、工具类，请直接拉到最后下载源码！也欢迎顺手给个Star～

须要的依赖

<dependency>
        <groupId>com.google.code.gson</groupId>
        <artifactId>gson</artifactId>
</dependency>

<dependency>
        <groupId>org.projectlombok</groupId>
        <artifactId>lombok</artifactId>
</dependency>
<dependency>
        <groupId>io.dropwizard.metrics</groupId>
        <artifactId>metrics-core</artifactId>
        <version>4.1.1</version>
</dependency>
<dependency>
        <groupId>io.dropwizard.metrics</groupId>
        <artifactId>metrics-jmx</artifactId>
        <version>4.1.1</version>
</dependency>
<dependency>
        <groupId>org.apache.commons</groupId>
        <artifactId>commons-lang3</artifactId>
</dependency>
<dependency>
        <groupId>io.netty</groupId>
        <artifactId>netty-all</artifactId>
        <version>4.1.29.Final</version>
</dependency>

Client端代码

package com.example.nettydemo.client;

import com.example.nettydemo.client.codec.*;
import com.example.nettydemo.client.codec.dispatcher.OperationResultFuture;
import com.example.nettydemo.client.codec.dispatcher.RequestPendingCenter;
import com.example.nettydemo.client.codec.dispatcher.ResponseDispatcherHandler;
import com.example.nettydemo.common.RequestMessage;
import com.example.nettydemo.common.string.StringOperation;
import com.example.nettydemo.util.IdUtil;
import io.netty.bootstrap.Bootstrap;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelPipeline;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.nio.NioChannelOption;
import io.netty.channel.socket.nio.NioSocketChannel;
import io.netty.handler.logging.LogLevel;
import io.netty.handler.logging.LoggingHandler;

import javax.net.ssl.SSLException;
import java.util.concurrent.ExecutionException;

public class Client {

public static void main(String[] args) throws InterruptedException, ExecutionException, SSLException {

    Bootstrap bootstrap = new Bootstrap();
    bootstrap.channel(NioSocketChannel.class);

    //客户端链接服务器最大容许时间，默认为30s
    bootstrap.option(NioChannelOption.CONNECT_TIMEOUT_MILLIS, 30 * 1000); //10s

    NioEventLoopGroup group = new NioEventLoopGroup();
    try {

        bootstrap.group(group);

        RequestPendingCenter requestPendingCenter = new RequestPendingCenter();
        LoggingHandler loggingHandler = new LoggingHandler(LogLevel.INFO);

        bootstrap.handler(new ChannelInitializer<NioSocketChannel>() {
            @Override
            protected void initChannel(NioSocketChannel ch) throws Exception {
                ChannelPipeline pipeline = ch.pipeline();

                pipeline.addLast(new FrameDecoder());
                pipeline.addLast(new FrameEncoder());

                pipeline.addLast(new ProtocolEncoder());
                pipeline.addLast(new ProtocolDecoder());

                pipeline.addLast(new ResponseDispatcherHandler(requestPendingCenter));
                pipeline.addLast(new OperationToRequestMessageEncoder());

//                    pipeline.addLast(loggingHandler);

            }
        });

        //链接服务
        ChannelFuture channelFuture = bootstrap.connect("127.0.0.1", 8888);
        //由于future是异步执行，因此须要先链接上后，再进行下一步操做
        channelFuture.sync();

        long streamId = IdUtil.nextId();
        /**
         * 发送数据测试，按照定义的规则组装数据
         */
//            OrderOperation orderOperation =  new OrderOperation(1001, "你好啊，hi");
                        RequestMessage requestMessage = new RequestMessage(streamId, new StringOperation(1234, "你好啊，hi"));

        //将future放入center
        OperationResultFuture operationResultFuture = new OperationResultFuture();
        requestPendingCenter.add(streamId, operationResultFuture);

        //发送消息
        for (int i = 0; i < 10; i++) {
            channelFuture.channel().writeAndFlush(requestMessage);
        }

        //阻塞等待结果,结果来了以后会调用ResponseDispatcherHandler去set结果

// OperationResult operationResult = operationResultFuture.get();
// //将结果打印
// System.out.println("返回:"+operationResult);

channelFuture.channel().closeFuture().get();

    } finally {
        group.shutdownGracefully();
    }

}

}
Server端代码

package com.example.nettydemo.server;

import com.example.nettydemo.server.codec.FrameDecoder;
import com.example.nettydemo.server.codec.FrameEncoder;
import com.example.nettydemo.server.codec.ProtocolDecoder;
import com.example.nettydemo.server.codec.ProtocolEncoder;
import com.example.nettydemo.server.handler.MetricsHandler;
import com.example.nettydemo.server.handler.ServerIdleCheckHandler;
import com.example.nettydemo.server.handler.ServerProcessHandler;
import io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelPipeline;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.nio.NioChannelOption;
import io.netty.channel.socket.nio.NioServerSocketChannel;
import io.netty.channel.socket.nio.NioSocketChannel;
import io.netty.handler.flush.FlushConsolidationHandler;
import io.netty.handler.logging.LogLevel;
import io.netty.handler.logging.LoggingHandler;
import io.netty.handler.traffic.GlobalTrafficShapingHandler;
import io.netty.util.concurrent.DefaultThreadFactory;
import io.netty.util.concurrent.UnorderedThreadPoolEventExecutor;
import lombok.extern.slf4j.Slf4j;

import javax.net.ssl.SSLException;
import java.security.cert.CertificateException;
import java.util.concurrent.ExecutionException;

/**
 * netty server 入口
 */
@Slf4j
public class Server {

public static void main(String... args) throws InterruptedException, ExecutionException, CertificateException, SSLException {

    ServerBootstrap serverBootstrap = new ServerBootstrap();
    //设置channel模式，由于是server因此使用NioServerSocketChannel
    serverBootstrap.channel(NioServerSocketChannel.class);

    //最大的等待链接数量
    serverBootstrap.option(NioChannelOption.SO_BACKLOG, 1024);
    //设置是否启用 Nagle 算法:用将小的碎片数据链接成更大的报文 来提升发送效率。
    //若是须要发送一些较小的报文，则须要禁用该算法
    serverBootstrap.childOption(NioChannelOption.TCP_NODELAY, true);

    //设置netty自带的log，并设置级别
    serverBootstrap.handler(new LoggingHandler(LogLevel.INFO));

    //thread
    //用户指定线程名
    NioEventLoopGroup bossGroup = new NioEventLoopGroup(0, new DefaultThreadFactory("boss"));
    NioEventLoopGroup workGroup = new NioEventLoopGroup(0, new DefaultThreadFactory("worker"));
    UnorderedThreadPoolEventExecutor businessGroup = new UnorderedThreadPoolEventExecutor(10, new DefaultThreadFactory("business"));

    //只能使用一个线程，因GlobalTrafficShapingHandler比较轻量级
    NioEventLoopGroup eventLoopGroupForTrafficShaping = new NioEventLoopGroup(0, new DefaultThreadFactory("TS"));

    try {
        //设置react方式
        serverBootstrap.group(bossGroup, workGroup);

        //metrics
        MetricsHandler metricsHandler = new MetricsHandler();

        //trafficShaping流量整形
        //long writeLimit 写入时控制, long readLimit 读取时控制 具体设置看业务修改
        GlobalTrafficShapingHandler globalTrafficShapingHandler = new GlobalTrafficShapingHandler(eventLoopGroupForTrafficShaping, 10 * 1024 * 1024, 10 * 1024 * 1024);

        //log
        LoggingHandler debugLogHandler = new LoggingHandler(LogLevel.DEBUG);
        LoggingHandler infoLogHandler = new LoggingHandler(LogLevel.INFO);

        //设置childHandler，按执行顺序放
        serverBootstrap.childHandler(new ChannelInitializer<NioSocketChannel>() {
            @Override
            protected void initChannel(NioSocketChannel ch) throws Exception {

                ChannelPipeline pipeline = ch.pipeline();

                pipeline.addLast("debugLog", debugLogHandler);
                pipeline.addLast("tsHandler", globalTrafficShapingHandler);
                pipeline.addLast("metricHandler", metricsHandler);
                pipeline.addLast("idleHandler", new ServerIdleCheckHandler());

                pipeline.addLast("frameDecoder", new FrameDecoder());
                pipeline.addLast("frameEncoder", new FrameEncoder());
                pipeline.addLast("protocolDecoder", new ProtocolDecoder());
                pipeline.addLast("protocolEncoder", new ProtocolEncoder());

                pipeline.addLast("infoLog", infoLogHandler);
                //对flush加强，减小flush次数牺牲延迟加强吞吐量
                pipeline.addLast("flushEnhance", new FlushConsolidationHandler(10, true));
                //为业务处理指定单独的线程池
                pipeline.addLast(businessGroup, new ServerProcessHandler());//businessGroup,
            }
        });

        //绑定端口并阻塞启动
        ChannelFuture channelFuture = serverBootstrap.bind(8888).sync();

        channelFuture.channel().closeFuture().sync();

    } finally {
        bossGroup.shutdownGracefully();
        workGroup.shutdownGracefully();
        businessGroup.shutdownGracefully();
        eventLoopGroupForTrafficShaping.shutdownGracefully();
    }

}

}
最后
以上介绍了Netty的基本用法，在代码中也作了一部分的关键注释，但可能还会有许多不足，也不可能知足全部人的要求，你们可根据本身的实际需求去改造此项目