Spring Cloud(02)–搭建订单-支付微服务模块的父工程在上一篇Spring Cloud(01)–初识Sp

在上一篇Spring Cloud(01)——初识Spring Cloud，回顾微服务及微服务架构中，我们初步了解了什么是SpringCloud和微服务，下面我们来先搭建一个rest微服务模块：订单（服务提供者）—支付（服务消费者）模块的父工程。< /p>

1、新建父工程项目空间< /h2>

1、新建一个maven项目，注意选择自己的maven版本< /p>

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2、设置字符集编码< /p>

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3、注解激活生效< /p>

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4、选择java版本为1.8< /p>

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5、添加文件过滤File Types，选择不显示哪些文件（可选）< /p>

< /p>

这里我添加了*.idea和 *.iml文件，再以后新建模块时，这两个文件将不会出现。< /p>

2、在父工程pom中添加依赖< /h2>

  <packaging< /span>>< /span>pom</packaging< /span>>< /span>

  <properties< /span>>< /span>

    <project.build.sourceEncoding< /span>>< /span>UTF-8</project.build.sourceEncoding< /span>>< /span>

    <maven.compiler.source< /span>>< /span>8</maven.compiler.source< /span>>< /span>

    <maven.compiler.target< /span>>< /span>8</maven.compiler.target< /span>>< /span>

    <junit.version< /span>>< /span>4.12</junit.version< /span>>< /span>

    <lombok.version< /span>>< /span>1.18.20</lombok.version< /span>>< /span>

    <log4j.version< /span>>< /span>1.2.12</log4j.version< /span>>< /span>

    <mysql.version< /span>>< /span>5.1.47</mysql.version< /span>>< /span>

    <druid.version< /span>>< /span>1.1.16</druid.version< /span>>< /span>

  </properties< /span>>< /span>
<dependencyManagement< /span>>< /span>

  <dependencie< /span>>< /span>
    <dependency< /span>>< /span>

      <groupId< /span>>< /span>org.springframework.boot</groupId< /span>>< /span>

      <artifactId< /span>>< /span>spring-boot-dependencie</artifactId< /span>>< /span>

      <version< /span>>< /span>2.2.2.RELEASE</version< /span>>< /span>

      <type< /span>>< /span>pom</type< /span>>< /span>

      <scope< /span>>< /span>import</scope< /span>>< /span>

    </dependency< /span>>< /span>
    <dependency< /span>>< /span>

      <groupId< /span>>< /span>org.springframework.cloud</groupId< /span>>< /span>

      <artifactId< /span>>< /span>spring-cloud-dependencie</artifactId< /span>>< /span>

      <version< /span>>< /span>Hoxton.SR1</version< /span>>< /span>

      <type< /span>>< /span>pom</type< /span>>< /span>

      <scope< /span>>< /span>import</scope< /span>>< /span>

    </dependency< /span>>< /span>
    <dependency< /span>>< /span>

      <groupId< /span>>< /span>com.alibaba.cloud</groupId< /span>>< /span>

      <artifactId< /span>>< /span>spring-cloud-alibaba-dependencie</artifactId< /span>>< /span>

      <version< /span>>< /span>2.1.0.RELEASE</version< /span>>< /span>

      <type< /span>>< /span>pom</type< /span>>< /span>

      <scope< /span>>< /span>import</scope< /span>>< /span>

    </dependency< /span>>< /span>
    <dependency< /span>>< /span>

      <groupId< /span>>< /span>mysql</groupId< /span>>< /span>

      <artifactId< /span>>< /span>mysql-connector-java</artifactId< /span>>< /span>

      <version< /span>>< /span>${mysql.version}</version< /span>>< /span>

    </dependency< /span>>< /span>

    <dependency< /span>>< /span>

      <groupId< /span>>< /span>com.alibaba</groupId< /span>>< /span>

      <artifactId< /span>>< /span>druid</artifactId< /span>>< /span>

      <version< /span>>< /span>$ { druid.version }</version< /span>>< /span>

    </dependency< /span>>< /span>
    <dependency< /span>>< /span>

      <groupId< /span>>< /span>junit</groupId< /span>>< /span>

      <artifactId< /span>>< /span>junit</artifactId< /span>>< /span>

      <version< /span>>< /span>${junit.version}</version< /span>>< /span>

    </dependency< /span>>< /span>

    <dependency< /span>>< /span>

      <groupId< /span>>< /span>org.projectlombok</groupId< /span>>< /span>

      <artifactId< /span>>< /span>lombok</artifactId< /span>>< /span>

      <version< /span>>< /span>${lombok.version}</version< /span>>< /span>

    </dependency< /span>>< /span>

    <dependency< /span>>< /span>

      <groupId< /span>>< /span>log4j</groupId< /span>>< /span>

      <artifactId< /span>>< /span>log4j</artifactId< /span>>< /span>

      <version< /span>>< /span>${log4j.version}</version< /span>>< /span>

    </dependency< /span>>< /span>

  </dependencie< /span>>< /span>

</dependencyManagement< /span>>< /span>

< /code>< /pre>
3、Maven中DependencyManagement和Dependencies的区别< /h2>

dependencyManagement是Maven中用来管理依赖版本号的方式，通常会在一个组织或者项目的最顶层的父POM看到dependencyManagement元素。< /p>
使用pom.xml中的dependencyManagement元素能让所有子项目引用一个依赖而不用显示的列出版本号。如：< /p>
<dependencie< /span>>< /span>

  </dependency< /span>>< /span>

    <groupId< /span>>< /span>log4j</groupId< /span>>< /span>

    <artifactId< /span>>< /span>log4j</artifactId< /span>>< /span>

  </dependency< /span>>< /span>

</dependencie< /span>>< /span>

< /code>< /pre>

这样做的好处是：如果有的个子项目都引用同一样依赖，则可以避免在每个使用的子项目里都声明一个版本号，这样当想升级或切换到另一个版本时，只需要在顶层父工程里更新，而不需要一个一个子项目的修改；另外如果某个子项目需要另外的版本，只需要声明version即可。< /p>
注意：< /p>

dependencyManagement里只是声明依赖，并不实现引入，因此子项目需要显示的声明需要用的依赖< /li>
如果不在子项目中声明依赖，是不会从父项目中继承下来的；只有在子项目中写了该依赖，才会从父项目中继续该项，并且version和scope都读取子父pom。< /li>
如果子项目中定义了版本号，那么会使用子项目中的版本。< /li>

< /ul>