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java實(shí)現(xiàn)簡易版簡易版dubbo

 更新時間：2021年11月22日 14:54:22   作者：ac_dao_di  
dubbo是阿里開源的rpc框架，目前是apache頂級開源項(xiàng)目，可以用來構(gòu)建微服務(wù)。本文主要介紹了如何通過java實(shí)現(xiàn)簡易版的dubbo,感興趣的小伙伴可以了解一下

一、dubbo簡介

實(shí)現(xiàn)一個簡易版的dubbo，首先看下dubbo是什么

dubbo是阿里開源的rpc框架，目前是apache頂級開源項(xiàng)目，可以用來構(gòu)建微服務(wù)。社區(qū)已經(jīng)到了3.0版本，生態(tài)活躍，原來是java寫的，現(xiàn)在有g(shù)o版本，支持云原生。

研究dubbo的目的

  • dubbo渾身是寶，用到了zk/javassit/netty/spring/spi等技術(shù)，可以說看懂了dubbo源碼，對自己是十分有幫助的。不僅能學(xué)習(xí)優(yōu)秀的代碼設(shè)計(jì)，理解solid原則，更能深刻理解rpc的實(shí)現(xiàn)原理，了解各種技術(shù)的運(yùn)用。
  • 當(dāng)前目前有不少大公司在使用，dubbo也是經(jīng)常被問的面試題，包括dubbo spi/dubbo通信流程，對于簡歷也是十分加分的。
  • 手寫dubbo，比看懂dubbo要難得多，讓自己透徹理解dubbo的設(shè)計(jì)細(xì)節(jié)，內(nèi)功修煉更上一層樓，以后再去看其他源碼會非?？?。

二、架構(gòu)設(shè)計(jì)

博主在看懂dubbo源碼的基礎(chǔ)上，自己動手實(shí)現(xiàn)dubbo最基礎(chǔ)的功能，包括服務(wù)注冊、服務(wù)發(fā)現(xiàn)、服務(wù)負(fù)載均衡、網(wǎng)絡(luò)通信、與spring boot集成等，以便更好掌握dubbo的實(shí)現(xiàn)原理。實(shí)現(xiàn)架構(gòu)如下：

Api層主要是面向框架使用者，通過注解就能使用簡易版dubbo。并實(shí)現(xiàn)了在spring boot中進(jìn)行自動配置。

目前微服務(wù)都是基于spring boot搭建的，大部分公司都從spring遷移到spring boot。整個實(shí)例都是基于spring boot來構(gòu)建的，基于自動化配置搞個starter，配置下yaml就能使用miniDubbo，無需配置xml。

服務(wù)發(fā)現(xiàn)基于zookeeper實(shí)現(xiàn)，所有發(fā)現(xiàn)的實(shí)例，暫存在注冊目錄中。

Zookeeper是一個樹狀的結(jié)構(gòu)，有三種節(jié)點(diǎn)類型，永久節(jié)點(diǎn)（需要自己刪除）、臨時節(jié)點(diǎn)（有會話的概念，當(dāng)zookeeper監(jiān)聽到會話斷開時，會刪除臨時節(jié)點(diǎn)）、有序節(jié)點(diǎn)。在dubbo中主要用的是臨時節(jié)點(diǎn)，用于實(shí)時感知服務(wù)實(shí)例上下線。

路徑格式：

/miniDubbo/${group}/${className}/providers/${ip:port}

集群失敗策略：主要有failover/failsafe/failback。

也就是當(dāng)consumer調(diào)用某個provider失敗時，采取的策略，failover表示失敗轉(zhuǎn)移，重試下一臺實(shí)例；failsafe表示不重試，不拋出異常，返回null。

模擬dubbo協(xié)議，這里通過netty實(shí)現(xiàn)網(wǎng)絡(luò)通信，底層使用JSON序列化，通過長度 + body的協(xié)議防止粘包。

Netty是java領(lǐng)域的一套高性能的nio異步網(wǎng)絡(luò)編程框架，底層也是基于java nio，已經(jīng)封裝好了網(wǎng)絡(luò)編程，實(shí)現(xiàn)網(wǎng)絡(luò)通信非常方便。在dubbo中用于provider-consumer建立長連接，避免重復(fù)建立連接。

整體思路是：consumer調(diào)用接口方法時，對接口進(jìn)行JDK代理，代理邏輯是通過服務(wù)發(fā)現(xiàn)找到一臺可用實(shí)例，將請求的類名、方法名、入?yún)⑦M(jìn)行打包、編碼，通過網(wǎng)絡(luò)請求發(fā)送給provider。在服務(wù)端拿到請求的類名、方法名、入?yún)⒑?，通過反射調(diào)用服務(wù)實(shí)例，并將結(jié)果的返回給consumer。

三、開發(fā)工具

需要安裝如下工具。

  • IDEA+JDK8+MAVEN
  • zookeeper

四、一步步實(shí)現(xiàn)

這里給出部分代碼，具體參考github：miniDubbo

4.1 客戶端消費(fèi)實(shí)現(xiàn)

4.1.1 掃描Reference注解，注入dubbo依賴

定義一個Reference注解，這個注解必須是運(yùn)行時注解，且至少可用在屬性上。

package com.jessin.practice.dubbo.processor;

import java.lang.annotation.Documented;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

/**
 * 消費(fèi)端注解
 * @Author: jessin
 * @Date: 19-11-25 下午9:48
 */
@Target({ ElementType.CONSTRUCTOR, ElementType.METHOD, ElementType.PARAMETER, ElementType.FIELD, ElementType.ANNOTATION_TYPE})
// 必須寫為runtime，否則獲取不到
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface Reference {

    String group() default "";

    String version() default "1.0.0";

    String timeout() default "3000";

    String failStrategy() default "failover";

    String retryCount() default "3";
}

在spring bean實(shí)例化后初始化前，對應(yīng)的是InstantiationAwareBeanPostProcessor#postProcessProperties，這個是bean實(shí)例化后第一個擴(kuò)展點(diǎn)，且在aware方法之前，進(jìn)行依賴反射注入，并設(shè)置動態(tài)代理，代理實(shí)現(xiàn)該屬性對應(yīng)的接口。

package com.jessin.practice.dubbo.processor;

import com.jessin.practice.dubbo.config.InterfaceConfig;
import com.jessin.practice.dubbo.config.MiniDubboProperties;
import java.lang.reflect.Field;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.BeansException;
import org.springframework.beans.PropertyValues;
import org.springframework.beans.factory.config.InstantiationAwareBeanPostProcessorAdapter;

/**
 * @Author: jessin
 * @Date: 19-11-25 下午9:49
 */
@Slf4j
public class ReferenceBeanPostProcessor extends InstantiationAwareBeanPostProcessorAdapter {
    private MiniDubboProperties miniDubboProperties;
    public ReferenceBeanPostProcessor(MiniDubboProperties miniDubboProperties) {
        this.miniDubboProperties = miniDubboProperties;
    }

    @Override
    public PropertyValues postProcessProperties(PropertyValues pvs, Object bean, String beanName)
            throws BeansException {
        Field[] fields = bean.getClass().getDeclaredFields();
        for (Field field : fields) {
            boolean isExist = field.isAnnotationPresent(Reference.class);
            if (isExist) {
                try {
                    if (!field.getType().isInterface()) {
                        throw new RuntimeException("dubbo依賴不是接口：" + field.getType().getName());
                    }
                    Reference  ref = field.getAnnotation(Reference.class);
                    log.info("嘗試注入接口代理，bean的{}屬性為：{}", beanName, ref);
                    // 私有屬性，必須設(shè)置為可訪問
                    field.setAccessible(true);
                    field.set(bean, JdkDynamicProxy.createProxy(field.getType(), transform(ref), miniDubboProperties));
                } catch (IllegalAccessException e) {
                    log.error("設(shè)置jdk實(shí)例出錯啦：{}", field);
                }
            }
        }
        return pvs;
    }

    private InterfaceConfig transform(Reference ref) {
        InterfaceConfig interfaceConfig = new InterfaceConfig();
        interfaceConfig.setGroup(ref.group());
        interfaceConfig.setVersion(ref.version());
        interfaceConfig.setTimeout(ref.timeout());
        interfaceConfig.setFailStrategy(ref.failStrategy());
        interfaceConfig.setRetryCount(ref.retryCount());
        return interfaceConfig;
    }
}

動態(tài)代理的邏輯非常簡單，基于注冊目錄找到可用的DubboInvoker，并發(fā)起網(wǎng)絡(luò)請求，傳輸請求id、類名、入?yún)?、超時時間、版本等信息。

package com.jessin.practice.dubbo.processor;

import com.alibaba.fastjson.JSONObject;
import com.jessin.practice.dubbo.config.InterfaceConfig;
import com.jessin.practice.dubbo.config.MiniDubboProperties;
import com.jessin.practice.dubbo.invoker.FailfastClusterInvoker;
import com.jessin.practice.dubbo.invoker.RpcInvocation;
import com.jessin.practice.dubbo.registry.RegistryDirectory;
import com.jessin.practice.dubbo.transport.Response;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;
import lombok.extern.slf4j.Slf4j;
/**
 * @Author: jessin
 * @Date: 19-11-25 下午9:54
 */
@Slf4j
public class JdkDynamicProxy<T> implements InvocationHandler {

    private String clazzName;

    private Object proxy;

    private RegistryDirectory registryDirectory;

    private FailfastClusterInvoker failfastClusterInvoker;

    private InterfaceConfig interfaceConfig;

    private MiniDubboProperties miniDubboProperties;

    public JdkDynamicProxy(Class<T> clazz, InterfaceConfig interfaceConfig, MiniDubboProperties miniDubboProperties) {
        proxy = Proxy.newProxyInstance(this.getClass().getClassLoader(), new Class[]{clazz}, this);
        this.clazzName = clazz.getName();
        registryDirectory = new RegistryDirectory(clazzName, miniDubboProperties.getRegistry(), interfaceConfig);
        failfastClusterInvoker = new FailfastClusterInvoker(registryDirectory);
        this.interfaceConfig = interfaceConfig;
    }


    public static <T>  Object createProxy(Class<T> clazz, InterfaceConfig interfaceConfig, MiniDubboProperties miniDubboProperties) {
        return new JdkDynamicProxy(clazz, interfaceConfig, miniDubboProperties).proxy;
    }

    /**
     * TODO 特殊方法不攔截。。
     * @param proxy
     * @param method
     * @param args
     * @return
     * @throws Throwable
     */
    @Override
    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
        if ("toString".equals(method.getName())) {
            return this.toString();
        }
        // todo group，attachment
        RpcInvocation rpcInvocation = new RpcInvocation();
        rpcInvocation.setInterfaceName(clazzName);
        rpcInvocation.setParameterType(method.getParameterTypes());
        rpcInvocation.setArgs(args);
        rpcInvocation.setMethodName(method.getName());
        rpcInvocation.setVersion(interfaceConfig.getVersion());
        Class returnType = method.getReturnType();

        log.info("jdk調(diào)用：{}，代理類為：{}，返回類型：{}", rpcInvocation, proxy, returnType);
        // todo 通過接口配置決定用哪種策略
        Response response = (Response)failfastClusterInvoker.invoke(rpcInvocation);
        if (returnType == Void.class) {
            return null;
        }
        JSONObject jsonObject = (JSONObject)response.getResult();
        return jsonObject.toJavaObject(returnType);
    }
}

4.1.2 使用注冊目錄刷新服務(wù)實(shí)例

主要是創(chuàng)建zk連接，訂閱該類的zk路徑，處理zk子節(jié)點(diǎn)事件，維護(hù)子節(jié)點(diǎn)上線和下線，并構(gòu)造DubboInvoker，建立網(wǎng)絡(luò)連接。該service接口的所有可用實(shí)例，都會存在一個注冊目錄中，并動態(tài)刷新。

package com.jessin.practice.dubbo.registry;

import com.google.common.collect.Lists;
import com.jessin.practice.dubbo.config.InterfaceConfig;
import com.jessin.practice.dubbo.invoker.DubboInvoker;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.stream.Collectors;
import lombok.extern.slf4j.Slf4j;

/**
 *  * 注冊項(xiàng)目錄，所有的dubboInvoker都保存到這里，實(shí)現(xiàn)zk listener，監(jiān)聽zk路徑變化，當(dāng)zk變化時，構(gòu)造DubboInvoker。
 *  * 每個service應(yīng)該有一個，同一個zk集群同一臺機(jī)器應(yīng)該只建立一個共享連接
 * @Author: jessin
 * @Date: 19-11-25 下午10:34
 */
@Slf4j
public class RegistryDirectory {

    private Map<String, DubboInvoker> ipAndPort2InvokerMap = new ConcurrentHashMap<>();

    private CuratorZookeeperClient curatorZookeeperClient;

    private InterfaceConfig interfaceConfig;

    private String providerPath;

    /**
     * TODO 創(chuàng)建zk連接，監(jiān)聽zk路徑創(chuàng)建DubboInvoker
     * @param path
     */
    public RegistryDirectory(String path, String registry, InterfaceConfig interfaceConfig) {
        this.interfaceConfig = interfaceConfig;
        // 監(jiān)聽group/接口名/providers，有變化時通知RegistryDirectory，也就是調(diào)用notify(url, listener, urls);
        this.providerPath = "/miniDubbo/" + interfaceConfig.getGroup() + "/" + path + "/providers";

        // TODO 創(chuàng)建zk連接，并創(chuàng)建RegistryDirectory，第一次時創(chuàng)建DubboInvoker
        // 判斷zk/redis。
        curatorZookeeperClient = RegistryManager.getCuratorZookeeperClient(registry);
        // todo 抽取subscribe方法
        List<String> children = curatorZookeeperClient.addTargetChildListener(providerPath, new ChildListener() {
                    @Override
                    public void childChanged(String path, List<String> children) {
                        log.info("監(jiān)聽到zk路徑變化:{}，children:{}", path, children);
                        processChildren(children);
                    }
                });

        processChildren(children);
    }


    public void processChildren(List<String> children) {
        try {
            if (children == null || children.size() == 0) {
                // 可能是遠(yuǎn)程抖動，或者zookeeper出問題了，造成所有服務(wù)實(shí)例下線，這里還需要通過心跳檢測。
                log.info("監(jiān)聽到zk路徑無子節(jié)點(diǎn):{}", providerPath);
                children = Lists.newArrayList();
            }
            List<String> added = children.stream()
                    .filter(one -> !ipAndPort2InvokerMap.containsKey(one))
                    .collect(Collectors.toList());
            List<String> finalChildren = children;
            List<String> deleted = ipAndPort2InvokerMap.keySet().stream()
                    .filter(one -> !finalChildren.contains(one))
                    .collect(Collectors.toList());
            log.info("監(jiān)聽到zk路徑：{}，子節(jié)點(diǎn)變化，新增zk節(jié)點(diǎn)：{}，刪除zk節(jié)點(diǎn)：{}", providerPath, added, deleted);

            added.forEach(ipAndPort -> {
                if (!ipAndPort2InvokerMap.containsKey(ipAndPort)) {
                    ipAndPort2InvokerMap.put(ipAndPort, new DubboInvoker(ipAndPort, interfaceConfig));
                }
            });
            deleted.forEach(ipAndPort -> {
                ipAndPort2InvokerMap.get(ipAndPort).destroy();
                ipAndPort2InvokerMap.remove(ipAndPort);
            });
        } catch (Exception e) {
            log.error("處理zk事件出錯", e);
        }

    }

    public List<DubboInvoker> getInvokerList() {
        return new ArrayList<>(ipAndPort2InvokerMap.values());
    }
}

4.1.3 Netty client網(wǎng)絡(luò)通信傳輸，編解碼器的實(shí)現(xiàn)

這里基于netty client 4.x api，也就是NioEventLoopGroup/NioSocketChannel等，快速開發(fā)網(wǎng)絡(luò)連接功能，異步發(fā)送網(wǎng)絡(luò)請求，處理各種網(wǎng)絡(luò)請求：

package com.jessin.practice.dubbo.netty;

import com.alibaba.fastjson.JSON;
import io.netty.bootstrap.Bootstrap;
import io.netty.channel.Channel;
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 lombok.extern.slf4j.Slf4j;


/**
 * @Author: jessin
 * @Date: 19-11-25 下午10:17
 */
@Slf4j
public class NettyClient {


    private String ipAndPort;
    /**
     * worker可以共用
     */
    private EventLoopGroup worker = new NioEventLoopGroup();

    private Channel socketChannel;

    private NettyClientHandler clientHandler = new NettyClientHandler();

    public NettyClient(String ipAndPort) {
        this.ipAndPort = ipAndPort;
        connect();
    }

    public void connect() {
        log.info("建立netty連接：{}", ipAndPort);
        Bootstrap bootstrap = new Bootstrap();
        try {
            bootstrap.group(worker).channel(NioSocketChannel.class)
                    .option(ChannelOption.SO_KEEPALIVE, true)
                    .option(ChannelOption.CONNECT_TIMEOUT_MILLIS, 3000)
                    .handler(new ChannelInitializer<SocketChannel>() {
                        // TODO 注意pipeline的順序
                        @Override
                        protected void initChannel(SocketChannel ch) throws Exception {
                            ch.pipeline()
                                    // clientHandler可以提為全局變量
                                    .addLast(new BaseEncoder())
                                    .addLast(new BaseDecoder())
                                    .addLast(clientHandler);
                        }
                    });
            // 客戶端是connect
            String[] values = ipAndPort.split(":");
            // TODO 考慮超時重連，心跳斷開重連，底層轉(zhuǎn)換為pipeline.connect()
            ChannelFuture channelFuture = bootstrap.connect(values[0], Integer.parseInt(values[1])).sync();
            if (channelFuture.isSuccess()) {
                log.info("與服務(wù)端建立連接成功：{}", ipAndPort);
            } else {
                log.error("與服務(wù)端建立連接失敗:{}", ipAndPort);
            }
            // 建立連接時保存下來，可能有需要連接多個客戶端
            this.socketChannel = channelFuture.channel();
        } catch (Exception e) {
            log.error("與服務(wù)端建立連接失敗:{}", ipAndPort, e);
            throw new RuntimeException("與服務(wù)端建立連接失敗: " + ipAndPort, e);
        }
    }

    /**
     * 對外發(fā)送數(shù)據(jù)接口
     * @param msg
     */
    public void send(Object msg) {
        // TODO 必須用writeAndFlush才會真正發(fā)出去，同時必須序列化為字符串，才能被編碼繼續(xù)往下走
        String jsonStr = JSON.toJSONString(msg);
        socketChannel.writeAndFlush(jsonStr);
    }

    public void close() {
        log.info("關(guān)閉訪問服務(wù)的連接：{}", ipAndPort);
        socketChannel.close();
        if (socketChannel != null && socketChannel.isActive()) {
            try {
                socketChannel.closeFuture().sync();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
        worker.shutdownGracefully();
    }
}

編碼器通過長度字段 + body實(shí)現(xiàn)，具體如下：

package com.jessin.practice.dubbo.netty;

import io.netty.buffer.ByteBuf;
import io.netty.channel.ChannelHandlerContext;
import io.netty.handler.codec.MessageToByteEncoder;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * todo protocol buf
 * @Author: jessin
 * @Date: 19-11-25 下午10:20
 */
public class BaseEncoder extends MessageToByteEncoder<String> {
    private Logger logger = LoggerFactory.getLogger(getClass());

    /**
     * Encode a message into a {@link ByteBuf}. This method will be called for each written message that can be handled
     * by this encoder.
     *
     * @param ctx the {@link ChannelHandlerContext} which this {@link MessageToByteEncoder} belongs to
     * @param msg the message to encode
     * @param out the {@link ByteBuf} into which the encoded message will be written
     * @throws Exception is thrown if an error occurs
     */
    @Override
    protected void encode(ChannelHandlerContext ctx, String msg, ByteBuf out) throws Exception {
        logger.info("對消息：{}進(jìn)行編碼", msg);
        byte[] wordBytes = msg.getBytes("utf-8");
        out.writeInt(wordBytes.length);
        out.writeBytes(wordBytes);
    }
}

對應(yīng)解碼器：

package com.jessin.practice.dubbo.netty;


/**
 * 發(fā)送的字節(jié)數(shù) + 字節(jié)信息
 * 按照這個格式進(jìn)行裝包和拆包，主要是會產(chǎn)生粘包的現(xiàn)象
 * 也就是發(fā)送方按照abc, def, 發(fā)送
 * 接收方收到的可能是a,bc,de,f，面向的是字節(jié)流，需要拆包解出命令
 *
 * @author jessin
 * @create 19-11-25 下午10:20
 **/
import io.netty.buffer.ByteBuf;
import io.netty.channel.ChannelHandlerContext;
import io.netty.handler.codec.ByteToMessageDecoder;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.util.List;

public class BaseDecoder extends ByteToMessageDecoder {
    private Logger logger = LoggerFactory.getLogger(getClass());
    private int totalBytes = -1;

    /**
     * Decode the from one {@link ByteBuf} to an other. This method will be called till either the input
     * {@link ByteBuf} has nothing to read when return from this method or till nothing was read from the input
     * {@link ByteBuf}.
     *
     * @param ctx the {@link ChannelHandlerContext} which this {@link ByteToMessageDecoder} belongs to
     * @param in  the {@link ByteBuf} from which to read data
     * @param out the {@link List} to which decoded messages should be added
     * @throws Exception is thrown if an error occurs
     */
    @Override
    protected void decode(ChannelHandlerContext ctx, ByteBuf in, List<Object> out) throws Exception {
        int readableBytes = in.readableBytes();
        if (totalBytes == -1 && readableBytes >= 4) {
            totalBytes = in.readInt();
        }
        int secondReadableBytes = in.readableBytes();
        if (totalBytes > 0 && secondReadableBytes >= totalBytes) {
            byte[] realData = new byte[totalBytes];
            in.readBytes(realData);
            out.add(new String(realData, "utf-8"));
            totalBytes = -1;
        }
        logger.info("讀取字節(jié)個數(shù)：{}，剩余字節(jié)個數(shù)：{}", readableBytes, secondReadableBytes);
    }
}

4.1.4 發(fā)起請求和接收響應(yīng)

如上，發(fā)送接口通過JSON進(jìn)行序列化。這里通過CountDownLatch實(shí)現(xiàn)客戶端等待功能，當(dāng)然也可以通過wait/notify實(shí)現(xiàn)。發(fā)送時設(shè)置自增id到請求體中，并保存到consumer本地map中，然后會調(diào)用CountDownLatch.await，并設(shè)置等待時間，進(jìn)行阻塞等待結(jié)果。在收到netty 響應(yīng)時，也就是netty channelRead有數(shù)據(jù)時，喚醒等待的調(diào)用線程。在channelRead中根據(jù)響應(yīng)的請求id，由netty線程設(shè)置上響應(yīng)結(jié)果，調(diào)用countDownLatch.countDown進(jìn)行喚醒。

package com.jessin.practice.dubbo.netty;

import com.alibaba.fastjson.JSON;
import com.jessin.practice.dubbo.transport.DefaultFuture;
import com.jessin.practice.dubbo.transport.Response;
import io.netty.channel.ChannelDuplexHandler;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelPromise;
import lombok.extern.slf4j.Slf4j;

/**
 * @Author: jessin
 * @Date: 19-11-25 下午10:25
 */
@Slf4j
public class NettyClientHandler extends ChannelDuplexHandler {
    @Override
    public void channelActive(ChannelHandlerContext ctx) throws Exception {
        log.info("客戶端和服務(wù)端建立連接成功");
        //ctx.writeAndFlush("{\"id\":1,\"rpcInvocation\":{\"interfaceName\":\"com.jessin.practice.dubbo.service.UserService\",\"methodName\":\"getUser\",\"parameterType\":[],\"version\":\"1.0.0\"}}");
    }

    /**
     * 對響應(yīng)進(jìn)行處理
     * @param ctx
     * @param msg
     * @throws Exception
     */
    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
        log.info("收到服務(wù)端消息：" + msg);
        // result字段為JSONObject
        Response response = JSON.parseObject((String)msg, Response.class);
        // todo 返回list/map，帶復(fù)雜key/value的是否有問題
        DefaultFuture.setResponse(response);
    }

    /**
     * TODO 發(fā)送消息前進(jìn)行攔截，oubound，只有channel.writeAndFlush()才能起作用，active里直接用ctx不起作用
     * @param ctx
     * @param msg
     * @param promise
     * @throws Exception
     */
    @Override
    public void write(ChannelHandlerContext ctx, Object msg, ChannelPromise promise) throws Exception {
        log.info("收到寫消息：" + msg);
        // 必須的！保證繼續(xù)往下走，發(fā)送出去，其實(shí)就是ctx.write(msg, promise)
        super.write(ctx, msg, promise);
        // TODO promise模式，依賴地獄，以及Future回調(diào)模式（guava、java8）
        promise.addListener(future -> {
            // 監(jiān)聽發(fā)送回調(diào)，看是否發(fā)送成功
            if (future.isSuccess()) {
                log.info("發(fā)送寫消息：{}，成功", msg);
            } else {
                log.info("發(fā)送消息失敗：{}", msg);
            }
        });
    }
}

4.2 服務(wù)實(shí)例曝光到注冊中心

4.2.1 在BeanDefinitionRegistryPostProcessor中處理@Service注解

服務(wù)端使用@Service注解：

package com.jessin.practice.dubbo.processor;

import java.lang.annotation.Documented;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

/**
 * @Author: jessin
 * @Date: 19-11-27 下午9:11
 */
@Target({ ElementType.TYPE, ElementType.CONSTRUCTOR, ElementType.METHOD, ElementType.PARAMETER, ElementType.FIELD, ElementType.ANNOTATION_TYPE})
// 必須寫為runtime，否則獲取不到
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface Service {
    String group() default "";

    String version() default "1.0.0";

    String timeout() default "3000";
}

需要掃描標(biāo)記有@Service的類，然后注冊到spring 容器，涉及到注冊BeanDefinition的，一般用到的擴(kuò)展點(diǎn)是BeanDefinitionRegistryPostProcessor#postProcessBeanDefinitionRegistry。這里為什么要自定義一個@Service注解，而不復(fù)用spring原有的@Service注解？是因?yàn)槲覀冞€要基于標(biāo)記有@Service的這個bean做一些處理操作，包括對該bean曝光到本地，開啟網(wǎng)絡(luò)監(jiān)聽，注冊到zk，這些動作需要封裝到“另外一個bean”來完成，我們需要注入“另外一個bean”這個Definition，這里也就是ServiceBean，下文講解。

package com.jessin.practice.dubbo.processor;

import com.jessin.practice.dubbo.config.InterfaceConfig;
import com.jessin.practice.dubbo.config.MiniDubboProperties;
import java.util.Set;
import org.springframework.beans.BeansException;
import org.springframework.beans.factory.BeanClassLoaderAware;
import org.springframework.beans.factory.config.BeanDefinition;
import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
import org.springframework.beans.factory.config.RuntimeBeanReference;
import org.springframework.beans.factory.support.BeanDefinitionRegistry;
import org.springframework.beans.factory.support.BeanDefinitionRegistryPostProcessor;
import org.springframework.beans.factory.support.RootBeanDefinition;
import org.springframework.context.annotation.AnnotationBeanNameGenerator;
import org.springframework.context.annotation.ClassPathBeanDefinitionScanner;
import org.springframework.core.annotation.AnnotationUtils;
import org.springframework.core.type.filter.AnnotationTypeFilter;
import org.springframework.util.ClassUtils;

/**
 * @Author: jessin
 * @Date: 19-11-27 下午9:24
 */
public class ServiceBeanPostProcessor implements BeanDefinitionRegistryPostProcessor, BeanClassLoaderAware {

    private AnnotationBeanNameGenerator annotationBeanNameGenerator = new AnnotationBeanNameGenerator();

    private MiniDubboProperties miniDubboProperties;

    private ClassLoader classLoader;

    public ServiceBeanPostProcessor(MiniDubboProperties miniDubboProperties) {
        this.miniDubboProperties = miniDubboProperties;
    }

    @Override
    public void postProcessBeanDefinitionRegistry(BeanDefinitionRegistry registry) throws BeansException {
        ClassPathBeanDefinitionScanner classPathBeanDefinitionScanner = new ClassPathBeanDefinitionScanner(registry, false);
        classPathBeanDefinitionScanner.addIncludeFilter(new AnnotationTypeFilter(Service.class));
        // 將該包下的@Service注解全部掃描為bean
        Set<BeanDefinition> beanDefinitionSet
                = classPathBeanDefinitionScanner.findCandidateComponents(miniDubboProperties.getPackagePath());
        for (BeanDefinition beanDefinition : beanDefinitionSet) {
            String beanName = annotationBeanNameGenerator.generateBeanName(beanDefinition, registry);
            registry.registerBeanDefinition(beanName, beanDefinition);
            BeanDefinition wrapper = new RootBeanDefinition(ServiceBean.class);
            wrapper.getPropertyValues().addPropertyValue("ref", new RuntimeBeanReference(beanName));
            wrapper.getPropertyValues().addPropertyValue("miniDubboProperties", miniDubboProperties);
            Class beanClass = ClassUtils.resolveClassName(beanDefinition.getBeanClassName(), classLoader);
            Service service = AnnotationUtils.findAnnotation(beanClass, Service.class);
            wrapper.getPropertyValues().addPropertyValue("interfaceConfig", transform(service));
            registry.registerBeanDefinition("dubbo_" + beanName, wrapper);
        }
    }


    @Override
    public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException {

    }

    private InterfaceConfig transform(Service ref) {
        InterfaceConfig interfaceConfig = new InterfaceConfig();
        interfaceConfig.setGroup(ref.group());
        interfaceConfig.setVersion(ref.version());
        interfaceConfig.setTimeout(ref.timeout());
        return interfaceConfig;
    }

    @Override
    public void setBeanClassLoader(ClassLoader classLoader) {
        this.classLoader = classLoader;
    }
}

4.2.2 解析注解參數(shù)，注冊服務(wù)到zookeeper

如上，我們在ServiceBean中，依賴標(biāo)記有@Service的bean，同時將其曝光到本地，開啟netty端口監(jiān)聽，注冊到zk，具體如下，見afterPropertiesSet方法：

package com.jessin.practice.dubbo.processor;

import com.jessin.practice.dubbo.config.InterfaceConfig;
import com.jessin.practice.dubbo.config.MiniDubboProperties;
import com.jessin.practice.dubbo.exporter.DubboExporter;
import com.jessin.practice.dubbo.netty.NettyManager;
import com.jessin.practice.dubbo.netty.NettyServer;
import com.jessin.practice.dubbo.registry.CuratorZookeeperClient;
import com.jessin.practice.dubbo.registry.RegistryManager;
import com.jessin.practice.dubbo.utils.NetUtils;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.DisposableBean;
import org.springframework.beans.factory.InitializingBean;

/**
 * @Author: jessin
 * @Date: 19-11-27 下午10:31
 */
@Slf4j
public class ServiceBean implements InitializingBean, DisposableBean {

    private NettyServer nettyServer;
    /**
     * zk地址
     */
    private CuratorZookeeperClient curatorZookeeperClient;

    private Object ref;

    private MiniDubboProperties miniDubboProperties;

    private InterfaceConfig interfaceConfig;

    public MiniDubboProperties getMiniDubboProperties() {
        return miniDubboProperties;
    }

    public void setMiniDubboProperties(MiniDubboProperties miniDubboProperties) {
        this.miniDubboProperties = miniDubboProperties;
    }

    public InterfaceConfig getInterfaceConfig() {
        return interfaceConfig;
    }

    public void setInterfaceConfig(InterfaceConfig interfaceConfig) {
        this.interfaceConfig = interfaceConfig;
    }

    public Object getRef() {
        return ref;
    }

    public void setRef(Object ref) {
        this.ref = ref;
    }

    @Override
    public void afterPropertiesSet() throws Exception {
        Class[] interfaces = ref.getClass().getInterfaces();
        if (interfaces.length <= 0) {
            throw new IllegalStateException(ref.getClass().getName() + "未實(shí)現(xiàn)接口");
        }
        // todo 目前只能實(shí)現(xiàn)一個接口
        String clazzName = interfaces[0].getName();
        log.info("曝光key：{}，ref：{}", clazzName, ref);
        // 暴露服務(wù) todo 版本
        DubboExporter.exportService(clazzName, ref);
        // 先開啟，再注冊
        // 判斷協(xié)議
        if ("dubbo".equals(miniDubboProperties.getProtocol())) {
            // 開啟netty server
            nettyServer = NettyManager.getNettyServer(miniDubboProperties.getPort());
        } else {
            throw new RuntimeException("unknown communicate protocol:" + miniDubboProperties.getProtocol());
        }
        // 判斷什么類型的注冊中心
        curatorZookeeperClient = RegistryManager.getCuratorZookeeperClient(miniDubboProperties.getRegistry());
        String providerPath = "/miniDubbo/" + interfaceConfig.getGroup() + "/" + clazzName + "/providers" + "/" + NetUtils.getServerIp() + ":" + miniDubboProperties.getPort();

        // 注冊zk，提煉register方法
        curatorZookeeperClient.create(providerPath, true);
    }

    @Override
    public void destroy() throws Exception {
        curatorZookeeperClient.doClose();
        nettyServer.close();
    }
}

4.2.3 開啟netty server，接收請求

在接受到consumer請求后，解碼，然后根據(jù)類名、方法名，找到對應(yīng)的曝光服務(wù)，進(jìn)行反射調(diào)用，將方法返回結(jié)果和請求id原樣寫出去，返回給客戶端。具體如下：

package com.jessin.practice.dubbo.netty;

import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.JSONObject;
import com.jessin.practice.dubbo.exception.DubboException;
import com.jessin.practice.dubbo.exporter.DubboExporter;
import com.jessin.practice.dubbo.invoker.RpcInvocation;
import com.jessin.practice.dubbo.transport.Request;
import com.jessin.practice.dubbo.transport.Response;
import com.jessin.practice.dubbo.utils.ArgDeserializerUtils;
import io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.ChannelDuplexHandler;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelHandler;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelOption;
import io.netty.channel.ChannelPromise;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioServerSocketChannel;
import java.lang.reflect.Method;
import lombok.extern.slf4j.Slf4j;

/**
 * @Author: jessin
 * @Date: 19-11-27 下午7:40
 */
@Slf4j
public class NettyServer {
    // todo 底層會啟動2*cpu個數(shù)的NioEventLoop，輪詢注冊到對應(yīng)的NioEventLoop運(yùn)行
    private EventLoopGroup boss = new NioEventLoopGroup();
    private EventLoopGroup worker = new NioEventLoopGroup();
    // 全局復(fù)用，是否需要考慮可共享？
    private ServerHandler serverHandler = new ServerHandler();
    private int port;

    public NettyServer(int port) {
        ServerBootstrap serverBootstrap = new ServerBootstrap();
        // boss線程池用于accept到達(dá)的請求，worker線程池對到達(dá)的請求進(jìn)行讀寫
        // child表示對到達(dá)的請求起作用，沒有child表示對ServerSocketChannel起作用
        // 服務(wù)端用NioServerSocketChannel
        ChannelFuture channelFuture;
        this.port = port;
        try {
            serverBootstrap.group(boss, worker)
                    .channel(NioServerSocketChannel.class)
                    .childOption(ChannelOption.SO_KEEPALIVE, true)
                    // todo option最終設(shè)置到j(luò)dk sever channel上
                    .option(ChannelOption.SO_BACKLOG, 1024)
                    .childHandler(new ChannelInitializer<SocketChannel>() {
                        @Override
                        protected void initChannel(SocketChannel ch) throws Exception {
                            // 對到達(dá)的請求進(jìn)行讀寫操作，責(zé)任鏈模式，ChannelPipeline
                            ch.pipeline()
                                    .addLast(new BaseDecoder())
                                    .addLast(new BaseEncoder())
                                    .addLast(serverHandler);
                        }
                    });
            // todo bind時，會新建NioServerSocketChannel，并注冊到NioEventLoop.selector中
            // todo 底層轉(zhuǎn)換為pipeline.bind()，最終調(diào)用serverSocketChannel.bind(socketAddress, 128);
            channelFuture = serverBootstrap.bind(port);
            // 下面會阻塞
            channelFuture.sync();
            log.info("服務(wù)器綁定端口：{}成功", port);
            // TODO 關(guān)閉時調(diào)用，客戶端也得關(guān)閉
            // channelFuture.channel().closeFuture().sync();
        } catch (Exception e) {
            throw new RuntimeException("bind port error:" + port, e);
        }
    }

    /**
     * 允許注冊到多個客戶端SocketChannel中
     */
    @ChannelHandler.Sharable
    class ServerHandler extends ChannelDuplexHandler {
        @Override
        public void channelActive(ChannelHandlerContext ctx) throws Exception {
            log.info("客戶端:{}和服務(wù)端建立連接成功", ctx.channel().remoteAddress());
        }

        @Override
        public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
            // 這里是String類型，已經(jīng)解碼了
            Request request = JSONObject.parseObject((String)msg, Request.class);
            log.info("收到請求消息：{}", msg);
            RpcInvocation rpcInvocation = request.getRpcInvocation();
            Object obj = DubboExporter.getService(rpcInvocation);
            if (obj == null) {
                throw new IllegalStateException("服務(wù)端未曝光接口：" + request);
            }
            Response response = new Response();
            response.setId(request.getId());
            try {
                log.info("開始反射調(diào)用：{}", msg);
                // todo 這里最好用線程池實(shí)現(xiàn)，不然會阻塞NioEventLoop
                Method method = obj.getClass().getMethod(rpcInvocation.getMethodName(), rpcInvocation.getParameterType());
                Object[] originArgs = ArgDeserializerUtils.parseArgs(method, rpcInvocation.getParameterType(), rpcInvocation.getArgs());
                log.info("入?yún)ⅲ簕}", originArgs);
                Object responseData = method.invoke(obj, originArgs);
                response.setResult(responseData);
                log.info("調(diào)用實(shí)例：{}，方法：{}，返回結(jié)果：{}",
                        obj, method, response);
            } catch (Exception e) {
                log.error("調(diào)用dubbo異常：{}", rpcInvocation, e);
                response.setException(true);
                response.setResult(new DubboException("服務(wù)端調(diào)用接口異常",  e));
            }
            // TODO 通過原來客戶端通道發(fā)送出去
            // 這里會走編碼嗎？，必須寫成String，或者改下Encoder
            ctx.writeAndFlush(JSON.toJSONString(response));
        }

        @Override
        public void channelInactive(ChannelHandlerContext ctx) throws Exception {
            log.info("收到客戶端退出的消息");
            ctx.close();
        }

        @Override
        public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
            log.error("IO出錯了...", cause);
        }

        @Override
        public void write(ChannelHandlerContext ctx, Object msg, ChannelPromise promise) throws Exception {
            log.info("發(fā)起寫請求：{}", msg);
            // TODO 寫的一般都有這個？
            super.write(ctx, msg, promise);
        }
    }

    /**
     * dubbo shutdown hook
     */
    public void close() {
        // TODO 這里是否有問題？？
        log.info("關(guān)閉端口：{}", port);
        boss.shutdownGracefully();
        worker.shutdownGracefully();
    }
}

4.3 自動化配置實(shí)現(xiàn)

這里根據(jù)yaml中配置的開關(guān)，自動開啟consumer/provider配置，需要注意的是，由于注入的@Service處理器是容器級別的后處理器，需要使用靜態(tài)方法進(jìn)行注入，避免過早初始化自動配置類，而且不能@autowirte 自動化屬性，需要通過方法獲取Environment，因?yàn)檫@個時候自動化屬性類還沒有對應(yīng)的后處理器對其進(jìn)行處理，拿到的屬性是空的，需要自己做bind。

最后在Resource目錄下，META-INF/spring.factories下，配置自動啟動即可：

package com.jessin.practice.dubbo.config;

import com.jessin.practice.dubbo.processor.ReferenceBeanPostProcessor;
import com.jessin.practice.dubbo.processor.Service;
import com.jessin.practice.dubbo.processor.ServiceBeanPostProcessor;
import lombok.extern.slf4j.Slf4j;
import org.springframework.boot.autoconfigure.condition.AnyNestedCondition;
import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;
import org.springframework.boot.context.properties.EnableConfigurationProperties;
import org.springframework.boot.context.properties.bind.Bindable;
import org.springframework.boot.context.properties.bind.Binder;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Conditional;
import org.springframework.context.annotation.Configuration;
import org.springframework.core.env.Environment;

/**
 * todo 自己調(diào)用自己，以及url支持，資源銷毀
 * @Author: jessin
 * @Date: 2021/10/26 9:27 PM
 */
@Configuration
@ConditionalOnClass(Service.class)
@EnableConfigurationProperties(MiniDubboProperties.class)
@Slf4j
public class MiniDubboAutoConfiguration {

    static {
        FastJsonConfig.config();
    }
    /**
     * 由于BeanFactoryPostProcessor是提前獲取的，這個時候CommonAnnotationBeanPostProcessor還沒注冊到beanFactory中，
     * serviceBeanPostProcessor注入的屬性為空
     */
//    @Autowired
//    private MiniDubboProperties miniDubboProperties;

//    public MiniDubboAutoConfiguration() {
//        log.info("init MiniDubboAutoConfiguration");
//    }

    /**
     *  由于這個Bean是BeanFactoryPostProcessor，提前獲取時，
     *  ConfigurationProperties的ConfigurationPropertiesBindingPostProcessor還沒注入到beanFactory中，
     *  所以MiniDubboProperties屬性沒法注入
     *  這里通過environment構(gòu)造
     * @param environment
     * @return
     */
    @Bean
    @Conditional(ServerCondition.class)
    @ConditionalOnMissingBean
    public static ServiceBeanPostProcessor serviceBeanPostProcessor(Environment environment) {
        MiniDubboProperties miniDubboProperties = getMiniDubboProperties(environment);
        return new ServiceBeanPostProcessor(miniDubboProperties);
    }
    static class ServerCondition extends AnyNestedCondition {

        ServerCondition() {
            super(ConfigurationPhase.REGISTER_BEAN);
        }

        @ConditionalOnProperty(prefix = MiniDubboProperties.PREFIX, name = "type", havingValue = "both")
        static class HostProperty {

        }

        @ConditionalOnProperty(prefix = MiniDubboProperties.PREFIX, name = "type", havingValue = "server")
        static class JndiNameProperty {

        }

    }

    /**
     * 使用靜態(tài)方法，防止造成自動化配置實(shí)例提前初始化，沒有進(jìn)行增強(qiáng)
     * @param environment
     * @return
     */
    @Bean
    @Conditional(ClientCondition.class)
    @ConditionalOnMissingBean
    public static ReferenceBeanPostProcessor referenceBeanPostProcessor(Environment environment) {
        MiniDubboProperties miniDubboProperties = getMiniDubboProperties(environment);
        return new ReferenceBeanPostProcessor(miniDubboProperties);
    }

    static class ClientCondition extends AnyNestedCondition {

        ClientCondition() {
            super(ConfigurationPhase.REGISTER_BEAN);
        }

        @ConditionalOnProperty(prefix = MiniDubboProperties.PREFIX, name = "type", havingValue = "both")
        static class HostProperty {

        }

        @ConditionalOnProperty(prefix = MiniDubboProperties.PREFIX, name = "type", havingValue = "client")
        static class JndiNameProperty {

        }

    }


    private static MiniDubboProperties getMiniDubboProperties(Environment environment) {
        MiniDubboProperties miniDubboProperties = Binder.get(environment) //首先要綁定配置器
                //再將屬性綁定到對象上
                .bind(MiniDubboProperties.PREFIX, Bindable.of(MiniDubboProperties.class) ).get(); //再獲取實(shí)例
        return miniDubboProperties;
    }


}

五、測試

5.1 編寫api

這里設(shè)置了5個接口，覆蓋了較多的場景，具體見：github

package com.jessin.practice.dubbo.service;

import com.jessin.practice.dubbo.model.User;
import com.jessin.practice.dubbo.model.UserParam;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

/**
 * @Author: jessin
 * @Date: 19-11-24 上午11:23
 */
public interface UserService {
    User getUser();

    User getUser(UserParam userParam);

    User getUser(int age);

    User getUser(UserParam userParam,
            int type,
            String note,
            int[] ages,
            List<Integer> list);

    User getUser(List<UserParam> list,
            ArrayList<UserParam> list2,
            Map<String, UserParam> userParamMap,
            HashMap<String, UserParam> userParamMap2);

    User getUser(List list, Map userParamMap);
}

5.2 實(shí)現(xiàn)api，標(biāo)記@Service

? ? 在miniDubboDemo中實(shí)現(xiàn)api，該工程基于spring boot實(shí)現(xiàn)。見miniDubboDemo

package com.example.demo.service;

import com.jessin.practice.dubbo.model.User;
import com.jessin.practice.dubbo.model.UserParam;
import com.jessin.practice.dubbo.processor.Service;
import com.jessin.practice.dubbo.service.UserService;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

/**
 * @Author: jessin
 * @Date: 19-11-27 下午11:33
 */
@Service(group="myGroup")
public class UserServiceImpl implements UserService {
    @Override
    public User getUser() {
        User user = new User();
        user.setId(1L);
        user.setName("小明");
        user.setAge(10);
        user.setNote("測試無參miniDubbo");
        return user;
    }

    @Override
    public User getUser(UserParam userParam) {
        User user = new User();
        user.setId(2L);
        user.setName("小紅");
        user.setAge(11);
        user.setNote("測試帶參數(shù)UserParam");
        return user;
    }

    @Override
    public User getUser(int age) {
        User user = new User();
        user.setId(2L);
        user.setName("小紅");
        user.setAge(11);
        user.setNote("測試帶參數(shù)int");
        return user;

    }

    @Override
    public User getUser(UserParam userParam, int type, String note, int[] ages, List<Integer> list) {
        User user = new User();
        user.setId(2L);
        user.setName("小紅");
        user.setAge(11);
        user.setNote("測試帶多個參數(shù)");
        return user;
    }

    @Override
    public User getUser(List<UserParam> list, ArrayList<UserParam> arrayList, Map<String, UserParam> map,
            HashMap<String, UserParam> hashMap) {
        User user = new User();
        user.setId(2L);
        user.setName("小紅");
        user.setAge(11);
        user.setNote("測試帶list/map泛型參數(shù)");
        return user;
    }

    @Override
    public User getUser(List list, Map userParamMap) {
        User user = new User();
        user.setId(2L);
        user.setName("小紅");
        user.setAge(11);
        user.setNote("測試帶list/map無參");
        return user;

    }
}

5.3 編寫controller接口，使用@Reference注入api依賴

也是在demo工程中，這里demo工程既作為provider，也作為consumer。

package com.example.demo.controller;

import com.google.common.collect.Lists;
import com.google.common.collect.Maps;
import com.jessin.practice.dubbo.model.User;
import com.jessin.practice.dubbo.model.UserParam;
import com.jessin.practice.dubbo.processor.Reference;
import com.jessin.practice.dubbo.service.UserService;
import java.util.HashMap;
import java.util.Map;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;

/**
 * TODO 泛化調(diào)用
 *
 * @Author: jessin
 * @Date: 19-8-3 下午4:25
 */
@RestController
public class HelloController {

    private Logger log = LoggerFactory.getLogger(getClass());

    @Reference(group = "myGroup")
    private UserService userService;

    /**
     * http://localhost:9999/practice/helloParam
     *
     * @return
     */
    @RequestMapping("/hello")
    public User hello(UserParam userParam, @RequestParam int type) {
        log.info("test miniDubbo param");
        if (type == 1) {
            return userService.getUser();
        } else if (type == 2) {
            return userService.getUser(userParam);
        } else if (type == 3) {
            return userService.getUser(3);
        } else if (type == 4) {
            return userService.getUser(userParam, 3, "hello", new int[]{1, 2, 3}, Lists.newArrayList(3, 5, 7));
        } else if (type == 5) {
            UserParam user2 = new UserParam();
            user2.setId(1132);
            user2.setName("hello");
            UserParam user3 = new UserParam();
            user3.setId(353);
            user3.setName("world");

            Map<String, UserParam> map = Maps.newHashMap();
            map.put("key1", user2);
            HashMap<String, UserParam> hashMap = Maps.newHashMap();
            hashMap.put("key2", user3);
            return userService.getUser(Lists.newArrayList(user2, user3),
                    Lists.newArrayList(userParam), map, hashMap);
        } else {
            UserParam user2 = new UserParam();
            user2.setId(1132);
            user2.setName("hello");
            UserParam user3 = new UserParam();
            user3.setId(353);
            user3.setName("world");
            Map<String, UserParam> map = Maps.newHashMap();
            map.put("key1", user2);
            HashMap<String, UserParam> hashMap = Maps.newHashMap();
            hashMap.put("key2", user3);
            return userService.getUser(Lists.newArrayList(userParam, user2, user3), map);
        }
    }
}

5.4 啟動步驟

5.4.1 啟動zk

博主的zk部署到云主機(jī)上，需保證2181端口已經(jīng)啟動：

ubuntu@VM-0-14-ubuntu:~$ lsof -i:2181
COMMAND   PID   USER   FD   TYPE    DEVICE SIZE/OFF NODE NAME
java     3904 ubuntu   27u  IPv6 545176752      0t0  TCP VM-0-14-ubuntu:35306->1.15.130.58:2181 (ESTABLISHED)
java    26361 ubuntu   45u  IPv6 452967153      0t0  TCP *:2181 (LISTEN)
java    26361 ubuntu   49u  IPv6 545176753      0t0  TCP VM-0-14-ubuntu:2181->1.15.130.58:35306 (ESTABLISHED)

5.4.2 部署api和miniDubbo到本地倉庫

部署api到本地倉庫：api，部署miniDubbo到本地倉庫：miniDubbo

mvn install

5.4.3 在demo yaml配置miniDubbo。

配置zk地址和掃描的服務(wù)端路徑（只在角色為服務(wù)端生效）

mini-dubbo:
  package-path: "@Service注解所在包"
  registry: "your_zk_ip:2181"

5.4.4 編譯demo為可執(zhí)行jar

mvn package

5.4.5 開啟兩個服務(wù)端

這兩個服務(wù)端都部署在云服務(wù)器上，參數(shù)說明：

server.port=9997，指定http端口

public.ip=1.15.130.58，可以指定當(dāng)前注冊到zk上的公網(wǎng)地址，如果用的是云主機(jī)的話，可以在云端部署兩臺服務(wù)實(shí)例，以便在本地能進(jìn)行服務(wù)發(fā)現(xiàn)和調(diào)用。

mini-dubbo.type=server，表示角色是服務(wù)端

catalina.base=xxx，設(shè)置的是日志目錄，改為你的即可。

啟動第一個provider實(shí)例： 默認(rèn)9999 http端口，20880 miniDubbo端口

 java -Dmini-dubbo.type=server -Dcatalina.base=/home/ubuntu/program/java/miniDubboDemo/tomcat1 -Dpublic.ip=1.15.130.58  -jar target/demo-0.0.1-SNAPSHOT.jar

啟動第二個provider實(shí)例： 默認(rèn)9998 http端口，20881 miniDubbo端口

 java -Dmini-dubbo.type=server -Dcatalina.base=/home/ubuntu/program/java/miniDubboDemo/tomcat2 -Dserver.port=9998 -Dmini-dubbo.port=20881 -Dpublic.ip=1.15.130.58  -jar target/demo-0.0.1-SNAPSHOT.jar

5.4.6 本地開啟客戶端進(jìn)行調(diào)用

在本地啟動客戶端，并與兩個provider建立連接：

java -Dmini-dubbo.type=client -Dcatalina.base=./tomcat3  -Dserver.port=9997 -jar target/demo-0.0.1-SNAPSHOT.jar```

通過客戶端restapi觸發(fā)miniDubbo調(diào)用，可以掛掉一臺服務(wù)，兩臺服務(wù)，看看效果，并通過type調(diào)用不同的api方法

http://localhost:9997/practice/hello?type=2

得到結(jié)果：

客戶端發(fā)起請求，可以看到調(diào)用的是20881這個服務(wù)：

服務(wù)端返回結(jié)果：

上面將20881銷毀后，再次調(diào)用客戶端發(fā)起請求，自動轉(zhuǎn)移到20880這個服務(wù)：

將20880也銷毀后，再次調(diào)用客戶端發(fā)起請求，直接拋出no provider異常：

六、總結(jié)

6.1 已完成功能列表

  • 基于zk服務(wù)注冊和服務(wù)發(fā)現(xiàn)
  • 基于netty + json序列化網(wǎng)絡(luò)通信
  • zk連接復(fù)用、netty client連接復(fù)用
  • 與spring boot集成

6.2 TODO LIST

通用需求：

  • spring容器銷毀時，關(guān)閉占用的資源，如netty client/netty server
  • 支持protobuf序列化
  • 支持http協(xié)議通信
  • netty超時重連，心跳斷開重連，銷毀dubbo invoker
  • zk抖動導(dǎo)致所有服務(wù)實(shí)例下線優(yōu)化
  • 其他注冊中心支持，如consul/redis
  • Attach/tag實(shí)現(xiàn)
  • 支持一個類多個版本實(shí)現(xiàn)
  • zk重新連接時，需要重新注冊關(guān)注的事件，恢復(fù)現(xiàn)場，對于服務(wù)端是重新注冊；對于客戶端是重新訂閱

provider功能：

  • 服務(wù)端優(yōu)雅啟動和優(yōu)雅下線，防止流量過早進(jìn)來，造成超時。在spring容器啟動成功后，再注冊到zk上。在spring容器銷毀時，先從zk取消注冊，最后再關(guān)閉客戶端連接。
  • 服務(wù)端請求用線程池實(shí)現(xiàn)，避免阻塞NioEventLoop
  • 服務(wù)端支持曝光實(shí)現(xiàn)多個接口的一個類

consumer功能：

  • netty client通過計(jì)數(shù)引用銷毀資源
  • 服務(wù)負(fù)載均衡算法：隨機(jī)/輪詢/加權(quán)
  • 集群失敗策略：failover/failsafe/failback

以上就是java實(shí)現(xiàn)簡易版簡易版dubbo的詳細(xì)內(nèi)容，更多關(guān)于dubbo的資料請關(guān)注腳本之家其它相關(guān)文章！

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