Short circuit @Value injection when using a source already covered by ConfigurationPropertySourcesPropertySource

[terminux]

Hi, I found that PropertySourcesPropertyResolver (a resolver that does not support short-circuiting) is used in these places:

• LoggingSystemProperties

spring-boot/spring-boot-project/spring-boot/src/main/java/org/springframework/boot/logging/LoggingSystemProperties.java

Line 165 in 08ce091

PropertySourcesPropertyResolver resolver = new PropertySourcesPropertyResolver(

• When the key is not a property name, such as when it is a SpEL expression:

spring-boot/spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/web/ErrorProperties.java

Line 35 in 5817c84

@Value("${error.path:/error}")

In this case ConfigurationPropertyName.of(key, true) will return null, and then defaultResolver (inherited from PropertySourcesPropertyResolver) will be used for resolution.

spring-boot/spring-boot-project/spring-boot/src/main/java/org/springframework/boot/context/properties/source/ConfigurationPropertySourcesPropertyResolver.java

Lines 87 to 97 in 5817c84

	ConfigurationPropertyName name = ConfigurationPropertyName.of(key, true);
	if (name != null) {
	try {
	ConfigurationProperty configurationProperty = attached.findConfigurationProperty(name);
	return (configurationProperty != null) ? configurationProperty.getValue() : null;
	}
	catch (Exception ex) {
	}
	}
	}
	return this.defaultResolver.getProperty(key, Object.class, false);

However the entire process property value will only be retrieved once, the current implementation is fine and we don't need to make any changes.

spring-boot/spring-boot-project/spring-boot/src/main/java/org/springframework/boot/context/properties/source/ConfigurationPropertySourcesPropertySource.java

Lines 66 to 68 in 5817c84

	if (name == null) {
	return null;
	}

• As @philwebb commented, Boot auto-configures PropertySourcesPlaceholderConfigurer, may need to wait Allow PropertySourcesPlaceholderConfigurer to customize PropertyResolver spring-framework#30304 to fix

spring-boot/spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/context/PropertyPlaceholderAutoConfiguration.java

Line 43 in 5817c84

return new PropertySourcesPlaceholderConfigurer();

Closes gh-28687

[terminux]

The current logging package does not allow the content of the context package to be imported, I am not sure if I need to modify the rules or use other methods to create property resolver.

spring-boot/src/checkstyle/import-control.xml

Line 80 in 2b5bd71

<disallow pkg="org.springframework.boot.context" />

[philwebb]

That restriction was introduced in #8611. I'm not sure if we should relax it or not. I wonder if we can get away with using the Environment directly since it's already a PropertyResolver.

[terminux]

Thank you for your reply! If you use Environment directly, we may need to set its ignoreUnresolvableNestedPlaceholders property to true to ensure that it is consistent with the original behavior. Since the Environment is modified, this will also affect the external use of it. Maybe we should make a copy of Environment?

[philwebb]

Good point. I need to think about this one for a bit.