Dubbo接口抽取及依赖版本统一-03

*前言：上两篇文章中，我们发现在两个项目dubbo-demo-provider和dubbo-demo-consumer中，接口DemoProviderService代码重复，pom.xml依赖代码重复，下面我们尝试将其统一。

①我们首先新建一个简单maven项目dubbo-demo-api，将接口DemoProviderService复制到该项目中，再将之前两个项目中的接口删除，此时，之前两个项目会报错。
②我们在项目dubbo-demo-provider和dubbo-demo-consumer中添入依赖，刷新后，报错信息应该会消失，此时完成了接口抽取的工作：

<dependency>
    <groupId>com.java</groupId>
    <artifactId>dubbo-demo-api</artifactId>
    <version>0.0.1-SNAPSHOT</version>
</dependency>

③我们再新建一个maven项目dubbo-demo-parent，注意packaging选项选择pom属性，该项目只做依赖版本的统一，没有实际功能：

在pom.xml中配置版本属性：

<properties>
    <dubbo-demo-api.version>0.0.1-SNAPSHOT</dubbo-demo-api.version>
    <dubbo.version>2.6.0</dubbo.version>
    <zkclient.version>0.10</zkclient.version>
    <curator-framework.version>4.0.1</curator-framework.version>
    <fastjson.version>1.2.46</fastjson.version>
    <log4j.version>1.2.17</log4j.version>
    <slf4j-api.version>1.7.25</slf4j-api.version>
    <commons-lang3.version>3.4</commons-lang3.version>
    <netty-all.version>4.0.35.Final</netty-all.version>
</properties>

再添入依赖：

<dependencyManagement>
    <dependencies>
        <dependency>
            <groupId>com.java</groupId>
            <artifactId>dubbo-demo-api</artifactId>
            <version>${dubbo-demo-api.version}</version>
        </dependency>
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>dubbo</artifactId>
            <version>${dubbo.version}</version>
        </dependency>
        <dependency>
            <groupId>com.101tec</groupId>
            <artifactId>zkclient</artifactId>
            <version>${zkclient.version}</version>
        </dependency>
        <dependency>
            <groupId>org.apache.curator</groupId>
            <artifactId>curator-framework</artifactId>
            <version>${curator-framework.version}</version>
        </dependency>
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>fastjson</artifactId>
            <version>${fastjson.version}</version>
        </dependency>
        <dependency>
            <groupId>log4j</groupId>
            <artifactId>log4j</artifactId>
            <version>${log4j.version}</version>
        </dependency>
        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-api</artifactId>
            <version>${slf4j-api.version}</version>
        </dependency>
        <dependency>
            <groupId>org.apache.commons</groupId>
            <artifactId>commons-lang3</artifactId>
            <version>${commons-lang3.version}</version>
        </dependency>
        <dependency>
            <groupId>io.netty</groupId>
            <artifactId>netty-all</artifactId>
            <version>${netty-all.version}</version>
        </dependency>
    </dependencies>
</dependencyManagement>

④在项目dubbo-demo-provider和dubbo-demo-consumer中添入父依赖后，所有依赖的版本信息应该会有黄色信息提示，将所有的版本信息全部删除，即可完成依赖版本的统一：

<parent>
    <groupId>com.java</groupId>
    <artifactId>dubbo-demo-parent</artifactId>
    <version>0.0.1-SNAPSHOT</version>
</parent>

*最后，我们测试接口发布和消费是否正常，依次启动Zookeeper服务ZkServer.bat，Tomcat服务Startup.bat，项目dubbo-demo-provider的ProviderTest，dubbo-demo-consumer的ConsumerTest，访问http://localhost:8080/，查看dubbo服务接口状态是否为正常，出现下图即为成功。