Property values and sources

Understand the idea

Value resolves a placeholder such as ${catalog.heading:Products}. PropertySource explicitly adds a properties file to the Environment. Boot loads its conventional application properties and YAML through its configuration-data support. A Framework-only context does not automatically perform that Boot loading, and default PropertySource support does not parse YAML.

A concrete example

@Value("${catalog.heading:Products}") String heading

In the application

See the independently runnable examples in Stage 24, Stage 25.

Configuration comes from the running application environment, not from Java field names.

See it in a working stage

• Stage 24: read a catalog setting with @Value
• Stage 25: load a separate catalog.properties file

Related concepts

• Spring bean
• Dependency injection