YAML - Spring Boot 下更好的配置选择？

Myth丶恋晨 2022-05-09 01:52 278阅读 0赞

> YAML an alternative to Properties file … with Spring Boot

![在这里插入图片描述][70]

对于许多Java工程师来说，一直习惯于使用properties文件或者xml文件来定义应用程序配置。但SpringBoot允许我们仅通过单个yml文件就可以完成所有与应用相关的配置。**补充说明一下：比较不同格式的配置文件的优劣，都会有一定的主观性**。但对于SpringBoot配置来说，依据[官方文档][Link 1]的说法，使用YAML似乎只有一个缺点：使用通过注解PropertySource加载YAML文件。

> YAML files can’t be loaded via the @PropertySource annotation. So in the case that you need to load values that way, you need to use a properties file.

### 什么是[YAML][]文件 ###

> It is a human friendly data serialization standard for all programming languages.

YAML是一种适用于所有编程语言的人性化数据序列化标准。YAML是JSON的子集，因而非常适用于定义树型配置参数。同时，YAML易于阅读，更利于工程师进行阅读和编辑。

### YAML的设计目标 ###

*  易于阅读
 *  可移植性高，适用于各种编程语言
 *  符合[native data structures][]
 *  包含一致性模型
 *  支持one-pass处理
 *  更好的语义表述性，易于扩展
 *  易于实现，易于使用

### 使用YAML注意事项 ###

你无法去校验YAML文件本身的完整性，相反，XML文件则总是要求格式完整。

YAML配置示例

environment:
        profiles: dev
        name: Developer App 
        url: http://dev.abc.com
        
        profiles: qa
        name: QA App 
        url: http://qa.abc.com

### 常见JAVA YAML解析器 ###

*  SnakeYAML
 *  JYaml
 *  YamlBeans
 *  JvYaml

[Spring Boot][]使用[SnakeYAML][]库加载解析YAML配置文件，**YamlPropertiesFactoryBean**将YAML文件解析为Properties文件，**YamlMapFactoryBean**将YAML文件解析为一个Map对象。

### **YamlPropertiesFactoryBean**加载YAML文件方式 ###

*  使用Java配置类

@Bean
      public static PropertySourcesPlaceholderConfigurer properties() {
          PropertySourcesPlaceholderConfigurer propertySourcesPlaceholderConfigurer = new PropertySourcesPlaceholderConfigurer();
          YamlPropertiesFactoryBean yaml = new YamlPropertiesFactoryBean();
          yaml.setResources(new ClassPathResource("appConfig.yml");
          propertySourcesPlaceholderConfigurer.setProperties(yaml.getObject());
          return propertySourcesPlaceholderConfigurer;
      }

*  使用XML组件配置

<context:annotation-config/>
     
    <bean id="yamlProperties" class="org.springframework.beans.factory.config.YamlPropertiesFactoryBean">
        <property name="resources" value="classpath:appConfig.yml"/>
    </bean>
     
    <context:property-placeholder properties-ref="yamlProperties"/>

#### 参考文档 ####

*  [https://stackoverflow.com/questions/47462950/application-yml-vs-application-properties-for-spring-boot][https_stackoverflow.com_questions_47462950_application-yml-vs-application-properties-for-spring-boot]
 *  [https://meetsnehal.wordpress.com/2015/09/12/yaml-an-alternative-to-properties-file-with-spring-boot/][https_meetsnehal.wordpress.com_2015_09_12_yaml-an-alternative-to-properties-file-with-spring-boot]

[70]: /images/20220509/473ed522a0904bba99a7a54ca8751908.png
[Link 1]: https://docs.spring.io/spring-boot/docs/current/reference/html/boot-features-external-config.html#boot-features-external-config-yaml-shortcomings
[YAML]: http://yaml.org/
[native data structures]: https://wordpress.com/post/84008038/58/redir.aspx?C=iIVoi758YUam3BoU91hAwS5KRK38t9JIG_sSS9Z9so3j2B5_qM_kbAAt1AwGIWBDvAXGWaEX0IQ.&URL=http%3a%2f%2fwww.yaml.org%2fspec%2f1.2%2fspec.html%23native+data+structure%2f%2f
[Spring Boot]: https://github.com/spring-projects/spring-boot/blob/master/spring-boot-starters/spring-boot-starter/pom.xml
[SnakeYAML]: https://bitbucket.org/asomov/snakeyaml
[https_stackoverflow.com_questions_47462950_application-yml-vs-application-properties-for-spring-boot]: https://stackoverflow.com/questions/47462950/application-yml-vs-application-properties-for-spring-boot
[https_meetsnehal.wordpress.com_2015_09_12_yaml-an-alternative-to-properties-file-with-spring-boot]: https://meetsnehal.wordpress.com/2015/09/12/yaml-an-alternative-to-properties-file-with-spring-boot/