SpringBoot配置文件@PropertySource 同时支持properties文件与yaml(yml)

Yaml(yml)最近比较流行的配置文件,相对properties,配置文件结构更清晰简洁.前段时间项目需要引入的配置，于是想用yml文件来增加新的属性配置，新增属性放在application.yml中是没问题的，但是放其他文件中，然后通过@PropertySource 引入时，却出现了问题，所有.yml中的参数配置全部读取无效，properties文件是正常的，后来在*上看到@PropertySource中存在factory参数，通过配置factory参数可以达到我们想要的效果。
@PropertySource factory属性的factory默认配置是Class<? extends PropertySourceFactory> factory() default PropertySourceFactory.class;, 我们再看下PropertySourceFactory的源码就可知道了,

/**
 * Strategy interface for creating resource-based {@link PropertySource} wrappers.
 *
 * @author Juergen Hoeller
 * @since 4.3
 * @see DefaultPropertySourceFactory
 */
public interface PropertySourceFactory {

	/**
	 * Create a {@link PropertySource} that wraps the given resource.
	 * @param name the name of the property source
	 * @param resource the resource (potentially encoded) to wrap
	 * @return the new {@link PropertySource} (never {@code null})
	 * @throws IOException if resource resolution failed
	 */
	PropertySource<?> createPropertySource(String name, EncodedResource resource) throws IOException;

}

默认实现是DefaultPropertySourceFactory,

/**
 * The default implementation for {@link PropertySourceFactory},
 * wrapping every resource in a {@link ResourcePropertySource}.
 *
 * @author Juergen Hoeller
 * @since 4.3
 * @see PropertySourceFactory
 * @see ResourcePropertySource
 */
public class DefaultPropertySourceFactory implements PropertySourceFactory {

	@Override
	public PropertySource<?> createPropertySource(String name, EncodedResource resource) throws IOException {
		return (name != null ? new ResourcePropertySource(name, resource) : new ResourcePropertySource(resource));
	}

}

我们所有做的只需继承DefaultPropertySourceFactory,然后对createPropertySource作下微调,就可以支持yaml了.

 public class MixPropertySourceFactory extends DefaultPropertySourceFactory {

  @Override
  public PropertySource<?> createPropertySource(String name, EncodedResource resource) throws IOException {
    String sourceName = name != null ? name : resource.getResource().getFilename();
    if (!resource.getResource().exists()) {
      return new PropertiesPropertySource(sourceName, new Properties());
    } else if (sourceName.endsWith(".yml") || sourceName.endsWith(".yaml")) {
      Properties propertiesFromYaml = loadYml(resource);
      return new PropertiesPropertySource(sourceName, propertiesFromYaml);
    } else {
      return super.createPropertySource(name, resource);
    }
  }

  private Properties loadYml(EncodedResource resource) throws IOException {
    YamlPropertiesFactoryBean factory = new YamlPropertiesFactoryBean();
    factory.setResources(resource.getResource());
    factory.afterPropertiesSet();
    return factory.getObject();
  }
}

这里做了个简单的文件后缀判断,如果是以.yml或.yaml结尾,则通过YamlPropertiesFactoryBean加载,其他情况则采用默认方式加载.如果大家需要支持json或xml等其他格式,也可在这里自动加入策略处理.
最后在SpringApplication上加入配置

@PropertySource(value = {
   "a.properties",
   "b.yml"
}, factory = MixPropertySourceFactory.class)

就可以了