What is use of applications.properties file?

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What is the use of applications.properties file?

📌 Need

The application.properties file in a Spring Boot application is used to configure various aspects of the application. It simplifies configuration management by allowing you to specify properties that control application behavior and settings.

🔍 What is it?

application.properties is a file where you can define configuration properties for your Spring Boot application. It is located in the src/main/resources directory.

- How it works: Spring Boot automatically loads the properties from this file at runtime and applies them to configure beans, components, and other aspects of the application.

- Example:

properties server.port=8080 spring.datasource.url=jdbc:mysql://localhost:3306/mydatabase spring.datasource.username=root spring.datasource.password=password

Key Concepts

  1. Customizing Application Behavior
  2. What it is: The file is used to customize various aspects of the application, such as server settings, database configurations, logging levels, and more.
  3. How it works: Properties are read by Spring Boot and used to set up beans and configure application components.
  4. Overriding Default Settings
  5. What it is: Allows you to override default settings provided by Spring Boot or third-party libraries.
  6. How it works: Define properties in application.properties to customize the default behavior without changing the source code.
  7. Profiles
  8. What it is: Supports multiple profiles for different environments (e.g., development, testing, production).
  9. How it works: Use application-{profile}.properties files (e.g., application-dev.properties) to define environment-specific settings.

❓ How it is used?

  1. Basic Configuration
  2. Usage: Define basic configuration properties such as server port, database URL, and credentials.
  3. Example:

properties server.port=8080 spring.datasource.url=jdbc:mysql://localhost:3306/mydatabase
4. Custom Properties
5. Usage: Define custom properties for application-specific settings.
6. Example:

properties app.custom.property=value
7. Profiles
8. Usage: Define properties for different profiles (e.g., application-dev.properties for development settings).
9. Example:

properties # application-dev.properties server.port=8081 spring.datasource.url=jdbc:mysql://localhost:3306/devdatabase

Summary

The application.properties file is used in Spring Boot to configure various aspects of an application, including server settings, database connections, and custom application properties. It supports environment-specific configurations through profiles and allows overriding default settings provided by Spring Boot or third-party libraries.

Follow-up Questions

  1. Can you use YAML format for configuration instead of properties?
  2. Yes, you can use application.yml for configuration, which offers a more structured format than application.properties.
  3. How do you specify different profiles in Spring Boot?
  4. Use application-{profile}.properties files (e.g., application-dev.properties) and activate profiles with the spring.profiles.active property.
  5. What is the precedence of configuration properties in Spring Boot?
  6. Configuration properties can be overridden by command-line arguments, environment variables, and properties files, with the latter having the lowest precedence.