Dubbo- entry to the master (a)

In order to enhance the personal technology, so start today self dubbo (of course, it must refer to the official documents and other articles you Great God ,, introductory title to the master, now is the beginning of the entry), in order to record the problems encountered and to share, here I refer to ( https://segmentfault.com/a/1190000019896723 ) his article, in his article talked about the development of several ways, xml, api-based annotation. Since springboot now in vogue, we all tend to java config way, so I just started to write about here java config mode.

First, first introduced maven (log4j may lead to conflict, so I gave it to removed), incorporated herein by reference recommended (dubbo official address on the git Dubbo: http://dubbo.apache.org/en-us/ , Dubbo git address: https://github.com/apache/dubbo ).

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.yqn.herman</groupId>
    <artifactId>study.dubbo</artifactId>
    <version>1.0-SNAPSHOT</version>

    <properties>
        <dubbo.version>2.7.5</dubbo.version>
        <java.compiler.version>1.8</java.compiler.version>
    </properties>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.0.4.RELEASE</version>
    </parent>

    <dependencies>
        <dependency>
            <groupId>org.apache.dubbo</groupId>
            <artifactId>dubbo</artifactId>
            <version>${dubbo.version}</version>
        </dependency>
        <dependency>
            <groupId>org.apache.dubbo</groupId>
            <artifactId>dubbo-dependencies-zookeeper</artifactId>
            <exclusions>
                <exclusion>
                    <artifactId>slf4j-log4j12</artifactId>
                    <groupId>org.slf4j</groupId>
                </exclusion>
            </exclusions>
            <version>${dubbo.version}</version>
            <type>pom</type>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter</artifactId>
        </dependency>
    </dependencies>

</project>

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Second, take a zookeeper local environment

From the introduction of a step we can know, dubbo need zk work together, as to why zk, there is still a reference map dubbo git, and can be seen from the figure dubbo need to have something as a service registry and discovery middleware the role and spring cloud in the Eureka equivalent, then dubbo preference is zk.

Since I was writing project in windows, so if you are windonws students can go directly to the official website to download zk ( https://www.apache.org/dyn/closer.cgi/zookeeper/ , note, windows must download bin.tar .gz at the end of the image file, then reference https://www.cnblogs.com/xiohao/p/9717364.html start

A single node can be used)

Third, the writing service, here we simply be an example, the receiving caller to the service parameters and print, and then return to service the caller (Note that the code inside the package name some of my own, you need to rewrite your own project):

　　Define an interface:

public interface ServiceProvider {
    String getMyName(String name);
}

　　Implement interface, the interface needs to be added here @Service notes (note that this comment cited do not spring, but the need to lead dubbo):

@Service
public class ServiceProviderImpl implements ServiceProvider {
    
    @Override
    public String getMyName(String name) {
        System.out.println("接收到服务调用者的名字:" + name);
        return "hello, " + name;
    }
}

　　java config形式注入dubbo启动需要的环境(此处有一个大坑，在设置 RegistryConfig 的时候我也写在了注释里边，就是虽然在代码里设置了port，但是没有生效，导致我一致连不上zk，原因是 dubbo在启动过程中会检测你是否有自定义的 RegistryConfig，从而

帮你把这个类给转化成 ConfigCenterConfig, 但是在转化的过程中，只赋值了 protocol, address等，port却被拿去用来设置id了，参考类 DubboBootstrap.useRegistryAsConfigCenterIfNecessary()）：

package com.yqn.herman.demo;

import org.apache.dubbo.config.ApplicationConfig;
import org.apache.dubbo.config.ProtocolConfig;
import org.apache.dubbo.config.ProviderConfig;
import org.apache.dubbo.config.RegistryConfig;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

/**
 * @author Lu, Hui
 * @since 2020/1/11
 **/
@Configuration
public class ServiceCustomerConfig {
    @Bean // #1 服务提供者信息配置，这里我们直接采用默认的
    public ProviderConfig providerConfig() {
        ProviderConfig providerConfig = new ProviderConfig();
        providerConfig.setTimeout(1000);
        return providerConfig;
    }

    @Bean // #2 分布式应用信息配置
    public ApplicationConfig applicationConfig() {
        ApplicationConfig applicationConfig = new ApplicationConfig();
        applicationConfig.setName("dubbo-annotation-provider"); //设置服务的名字，分布式环境下必须保证唯一性，和spring cloud下的 application name一样
        return applicationConfig;
    }

    @Bean // #3 注册中心信息配置
    public RegistryConfig registryConfig() {
        RegistryConfig registryConfig = new RegistryConfig();
        registryConfig.setProtocol("zookeeper");
        registryConfig.setAddress("localhost:2181"); // zk server 地址,一定要在这里把port加上
        //registryConfig.setPort(2181); // zk client 监听端口， 设置了也没有任何效果
        return registryConfig;
    }

    @Bean // #4 使用协议配置，这里使用 dubbo
    public ProtocolConfig protocolConfig() {
        ProtocolConfig protocolConfig = new ProtocolConfig();
        protocolConfig.setName("dubbo");
        protocolConfig.setPort(20880);
        return protocolConfig;
    }
}

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启动并发布我们的服务（注意，这个时候需要我们先启动 zk，不然会报错，我的zk是下载下来后的默认端口）：

package com.yqn.herman.demo;


import org.apache.dubbo.config.spring.context.annotation.EnableDubbo;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;


import java.util.concurrent.CountDownLatch;

/**
 * @author Lu, Hui
 * @since 2020/1/11
 **/
@SpringBootApplication
@EnableDubbo(scanBasePackages = "com.yqn.herman.demo") //参考其注释可以知道，这里是所有 @Service 注解标注的服务的包，也就是我们要对外发布的所有服务
public class ServiceStarter {

    public static void main(String[] args) throws Exception {
        SpringApplication.run(ServiceStarter.class);
        new CountDownLatch(1).await(); //
    }

}

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到这里基本没有意外了，启动成功：

接下来，我们需要写服务消费者了：

首先定义我们的消费者：

package com.yqn.herman.demo.com.yqn.herman.client;

import com.yqn.herman.demo.provider.ServiceProvider;
import org.apache.dubbo.config.annotation.Reference;
import org.springframework.stereotype.Component;

/**
 * @author Lu, Hui
 * @since 2020/1/11
 **/
@Component // 在这里，我的消费者和服务提供者在同一个项目，所以我直接引用了，如果你分开写了，需要在你的客户端引入服务者的jar包
public class ServiceConsumer {

    @Reference //该注解类似于 spring cloud 的 feign, 通过对这个注解的处理来找到需要的服务
    private ServiceProvider serviceProvider;

    public void call(String name) {
        serviceProvider.getMyName(name);
    }
}

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接着，和服务端一样，我们需要配置dubbo客户端的环境：

package com.yqn.herman.demo.com.yqn.herman.client;

import org.apache.dubbo.config.ApplicationConfig;
import org.apache.dubbo.config.ConsumerConfig;
import org.apache.dubbo.config.RegistryConfig;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

import java.util.HashMap;
import java.util.Map;

/**
 * @author Lu, Hui
 * @since 2020/1/11
 **/
@Configuration
public class ClientConfig {
    @Bean // 应用配置
    public ApplicationConfig applicationConfig() {
        ApplicationConfig applicationConfig = new ApplicationConfig();
        applicationConfig.setName("dubbo-annotation-consumer");
        Map<String, String> stringStringMap = new HashMap<String, String>();
        stringStringMap.put("qos.enable","true");
        stringStringMap.put("qos.accept.foreign.ip","false");
        stringStringMap.put("qos.port","33333");
        applicationConfig.setParameters(stringStringMap);
        return applicationConfig;
    }

    @Bean // 服务消费者配置
    public ConsumerConfig consumerConfig() {
        ConsumerConfig consumerConfig = new ConsumerConfig();
        consumerConfig.setTimeout(3000);
        return consumerConfig;
    }

    @Bean // 配置注册中心
    public RegistryConfig registryConfig() {
        RegistryConfig registryConfig = new RegistryConfig();
        registryConfig.setProtocol("zookeeper");
        registryConfig.setAddress("localhost:2181");
        return registryConfig;
    }
}

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最后，启动客户端，调用一次服务：

package com.yqn.herman.demo.com.yqn.herman.client;

import org.apache.dubbo.config.spring.context.annotation.EnableDubbo;
import org.springframework.boot.CommandLineRunner;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

/**
 * @author Lu, Hui
 * @since 2020/1/11
 **/
@SpringBootApplication
@EnableDubbo(scanBasePackages = "com.yqn.herman.demo.com.yqn.herman.client") //需要服务注入的包，也就是consumer在的包
public class ClientStarter implements CommandLineRunner {

    private ServiceConsumer serviceConsumer;

    public static void main(String[] args) {
        SpringApplication.run(ClientStarter.class);
    }

    public ClientStarter(ServiceConsumer serviceConsumer) {
        this.serviceConsumer = serviceConsumer;
    }

    @Override //这里我实现了 CommandLineRunner 接口，用于在程序启动结束执行一次该方法
    public void run(String... args) throws Exception {
        serviceConsumer.call("小甜甜");
    }
}

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可以看到，服务端接收到了请求：

到这里，我们就算是入门了，可以自己写一个 Hello Word 级别的dubbo例子了。如果有任何问题，写在评论区，我们一起讨论。

Dubbo- entry to the master (a)

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