第1章 第一个 Dubbo 项目

2019-07-12  本文已影响0人  原水寒

本文实现一个最简的 Demo（直接以 Dubbo 官方 demo 为例，略作简化），注册中心使用 zookeeper，示例代码使用 dubbo 2.6.6。

实例代码地址：https://github.com/zhaojigang/dubbo-demo

一、安装启动 zk

安装启动 zk： https://zookeeper.apache.org/doc/current/zookeeperStarted.html
安装启动 zkui（zk 图形化界面客户端）：https://github.com/DeemOpen/zkui

二、Demo

image.png

dubbo-demo-api：提供 api 服务接口；
dubbo-demo-provider：服务端，实现 api 接口 + 启动服务端；
dubbo-demo-consumer：消费端，启动消费端。

总 pom.xml

<?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.alibaba</groupId>
    <artifactId>dubbo-demo</artifactId>
    <packaging>pom</packaging>
    <version>1.0-SNAPSHOT</version>
    <modules>
        <!-- 接口定义 -->
        <module>dubbo-demo-api</module>
        <!-- 服务提供者 -->
        <module>dubbo-demo-provider</module>
        <!-- 服务消费者 -->
        <module>dubbo-demo-consumer</module>
    </modules>

    <build>
        <plugins>
            <!-- 使用 java8 编译 -->
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <configuration>
                    <source>1.8</source>
                    <target>1.8</target>
                </configuration>
            </plugin>
        </plugins>
    </build>
</project>

2.1、dubbo-demo-api

pom.xml

<?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">
    <parent>
        <artifactId>dubbo-demo</artifactId>
        <groupId>com.alibaba</groupId>
        <version>1.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>
    <artifactId>dubbo-demo-api</artifactId>
</project>

接口定义 com.alibaba.dubbo.demo.DemoService

public interface DemoService {
    String sayHello(String name);
}

2.2、dubbo-demo-provider

pom.xml

<?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">
    <parent>
        <artifactId>dubbo-demo</artifactId>
        <groupId>com.alibaba</groupId>
        <version>1.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>

    <artifactId>dubbo-demo-provider</artifactId>
    <properties>
        <dubbo.version>2.6.6</dubbo.version>
    </properties>

    <dependencies>
        <!-- 服务接口 -->
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>dubbo-demo-api</artifactId>
            <version>1.0-SNAPSHOT</version>
        </dependency>
        <!-- 注册中心 -->
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>dubbo-registry-zookeeper</artifactId>
            <version>${dubbo.version}</version>
        </dependency>
        <!-- 与 spring 融合 -->
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>dubbo-config-spring</artifactId>
            <version>${dubbo.version}</version>
        </dependency>
        <!-- 协议 -->
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>dubbo-rpc-dubbo</artifactId>
            <version>${dubbo.version}</version>
        </dependency>
        <!-- 通信框架 -->
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>dubbo-remoting-netty4</artifactId>
            <version>${dubbo.version}</version>
        </dependency>
        <!-- 序列化 -->
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>dubbo-serialization-hessian2</artifactId>
            <version>${dubbo.version}</version>
        </dependency>
    </dependencies>
</project>

此处按需引入依赖，而不是引入 dubbo all in one jar 包，防止加载太多无用的类。

服务实现 com.alibaba.dubbo.demo.provider.DemoServiceImpl

public class DemoServiceImpl implements DemoService {
    @Override
    public String sayHello(String name) {
        System.out.println("provider received: " + name);
        return "hello, " + name;
    }
}

配置文件 META-INF/spring/dubbo-demo-provider.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:dubbo="http://dubbo.apache.org/schema/dubbo"
       xmlns="http://www.springframework.org/schema/beans"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-4.3.xsd
       http://dubbo.apache.org/schema/dubbo http://dubbo.apache.org/schema/dubbo/dubbo.xsd">
    <!-- 应用名，通常与 artifactId 相同即可 -->
    <dubbo:application name="demo-provider"/>
    <!-- 注册中心 -->
    <dubbo:registry address="zookeeper://127.0.0.1:2181" check="false"/>
    <!-- 暴露协议 -->
    <dubbo:protocol name="dubbo" port="20880"/>
    <!-- spring bean -->
    <bean id="demoService" class="com.alibaba.dubbo.demo.provider.DemoServiceImpl"/>
    <!-- 声明暴露的服务 -->
    <dubbo:service interface="com.alibaba.dubbo.demo.DemoService" ref="demoService"/>
</beans>

服务端启动

package com.alibaba.dubbo.demo.provider;

import org.springframework.context.support.ClassPathXmlApplicationContext;

public class Provider {
    public static void main(String[] args) throws Exception {
        ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext(new String[]{"META-INF/spring/dubbo-demo-provider.xml"});
        context.start();

        System.out.println("provider start success!");
        System.in.read(); // press any key to exit
    }
}

2.3、dubbo-demo-consumer

pom.xml

<?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">
    <parent>
        <artifactId>dubbo-demo</artifactId>
        <groupId>com.alibaba</groupId>
        <version>1.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>

    <artifactId>dubbo-demo-consumer</artifactId>
    <properties>
        <dubbo.version>2.6.6</dubbo.version>
    </properties>

    <dependencies>
        <!-- 服务接口 -->
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>dubbo-demo-api</artifactId>
            <version>1.0-SNAPSHOT</version>
        </dependency>
        <!-- 注册中心 -->
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>dubbo-registry-zookeeper</artifactId>
            <version>${dubbo.version}</version>
        </dependency>
        <!-- 与 spring 融合 -->
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>dubbo-config-spring</artifactId>
            <version>${dubbo.version}</version>
        </dependency>
        <!-- 协议 -->
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>dubbo-rpc-dubbo</artifactId>
            <version>${dubbo.version}</version>
        </dependency>
        <!-- 通信框架 -->
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>dubbo-remoting-netty4</artifactId>
            <version>${dubbo.version}</version>
        </dependency>
        <!-- 序列化 -->
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>dubbo-serialization-hessian2</artifactId>
            <version>${dubbo.version}</version>
        </dependency>
    </dependencies>
</project>

配置文件 META-INF/spring/dubbo-demo-consumer.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:dubbo="http://dubbo.apache.org/schema/dubbo"
       xmlns="http://www.springframework.org/schema/beans"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-4.3.xsd
       http://dubbo.apache.org/schema/dubbo http://dubbo.apache.org/schema/dubbo/dubbo.xsd">
    <!-- 应用名，通常与 artifactId 相同即可 -->
    <dubbo:application name="demo-consumer"/>
    <!-- 注册中心 -->
    <dubbo:registry address="zookeeper://127.0.0.1:2181"/>
    <!-- 生成远端服务的代理对象, 之后可以向调用本地服务一样调用远端服务 -->
    <dubbo:reference id="demoService" check="false" interface="com.alibaba.dubbo.demo.DemoService"/>
</beans>

消费端启动

package com.alibaba.dubbo.demo.consumer;

import com.alibaba.dubbo.demo.DemoService;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class Consumer {
    public static void main(String[] args) {
        ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext(new String[]{"META-INF/spring/dubbo-demo-consumer.xml"});
        context.start();
        DemoService demoService = (DemoService) context.getBean("demoService"); // get remote service proxy

        while (true) {
            try {
                Thread.sleep(1000);
                String hello = demoService.sayHello("world"); // call remote method
                System.out.println(hello); // get result
            } catch (Throwable throwable) {
                throwable.printStackTrace();
            }
        }
    }
}

三、测试

  1. 启动 dubbo-demo-provider
  2. 启动 dubbo-demo-consumer，查看 provider 实现类的输出和 consumer 的响应输出
  3. 在 zkui 上查看服务注册情况

/dubbo
-- /com.alibaba.dubbo.demo.DemoService
---- /providers
------ /dubbo://172.20.10.2:20880/com.alibaba.dubbo.demo.DemoService?anyhost=true&application=demo-provider&bean.name=com.alibaba.dubbo.demo.DemoService&dubbo=2.0.2&generic=false&interface=com.alibaba.dubbo.demo.DemoService&methods=sayHello&pid=8958&side=provider&timestamp=1562658149859
---- /consumers
------ /consumer://172.20.10.2/com.alibaba.dubbo.demo.DemoService?application=demo-consumer&category=consumers&check=false&dubbo=2.0.2&interface=com.alibaba.dubbo.demo.DemoService&methods=sayHello&pid=8982&side=consumer&timestamp=1562658152955
---- /configurators
---- /routers

注意：dubbo 2.7.x 之后对注册 url 进行了简化，解决了 推送量大 -> 存储数据量大 -> 网络传输量大 -> 延迟严重 的问题，具体见 阿里技术专家详解 Dubbo 实践，演进及未来规划

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