Passing a Map<String, String> with application.properties in Spring Boot applications can simplify configurations when you want to manage multiple related values together. This article explains how to configure a Map<String, String> using application.properties and access it in a Spring Boot application.

Basics of application.properties

The application.properties file is a key-value pair-based configuration file. It is a central configuration file in Spring Boot applications often used to externalize configuration, allowing you to configure application settings distinct from application logic.

Defining a Map in application.properties

When you want to configure a Map<String, String> , you typically represent it in a flat structure, where keys represent the final map key paths. Here's a basic example of how you might define a map called my.map :

• Prefix: The @ConfigurationProperties annotation with the prefix attribute specifies that the properties starting with my should be bound to this component.
• Map Binding: Spring Boot automatically binds the properties my.map.key1 , my.map.key2 , etc., to the map field in the MyProperties class.
• Injection: MyProperties is injected into the controller using Spring's @Autowired annotation.
• Access: You can access the map through its getter method, enabling you to utilize it within your application seamlessly.
• Nested Properties: If you require nested properties and maps, you can adopt a more complex structure of nested classes corresponding to nested property paths.
• Profiles: Consider using Spring Profiles to manage environment-specific properties for maps. This facilitates different property values for development, testing, and production environments.