关于@PropertySources注解的理解：http://www.imooc.com/article/252889?block_id=tuijian_wz
public interface PropertySources extends Iterable<PropertySource<?>> {
/**
* Return a sequential {@link Stream} containing the property sources.
* @since 5.1
*/
default Stream<PropertySource<?>> stream() {
return StreamSupport.stream(spliterator(), false);
}
/**
* Return whether a property source with the given name is contained.
* @param name the {@linkplain PropertySource#getName() name of the property source} to find
*/
boolean contains(String name);
/**
* Return the property source with the given name, {@code null} if not found.
* @param name the {@linkplain PropertySource#getName() name of the property source} to find
*/
@Nullable
PropertySource<?> get(String name);
这就是PropertySources的接口，那么它的实现类在哪里？是MutablePropertySources,
}
PropertySources是由工厂类生成的，看看DefaultPropertySourceFactory
public class DefaultPropertySourceFactory implements PropertySourceFactory { @Override public PropertySource<?> createPropertySource(@Nullable String name, EncodedResource resource) throws IOException { return (name != null ? new ResourcePropertySource(name, resource) : new ResourcePropertySource(resource)); } }
然后又调用ResourcePropertySource类，在该类下，实现了对配置文件的加载loadProperties(resource).
public class ResourcePropertySource extends PropertiesPropertySource {
/** The original resource name, if different from the given name. */
@Nullable
private final String resourceName;
/**
* Create a PropertySource having the given name based on Properties
* loaded from the given encoded resource.
*/
public ResourcePropertySource(String name, EncodedResource resource) throws IOException {
super(name, PropertiesLoaderUtils.loadProperties(resource));
this.resourceName = getNameForResource(resource.getResource());
}
剩下的就是java的文件的加载过程，细节就不再讨论了