Spring Boot Application Properties

1. Introduction

In Spring Boot, configuration is managed using:

application.properties
application.yml

These files help to:

Customize application behavior
Avoid changing source code
Manage environment-specific settings

2. Why Use application.properties

Centralized configuration
Easy to override default settings
Supports multiple environments (dev, test, prod)
Reduces hardcoding

3. File Location

Configuration file is placed inside:

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src/main/resources

4. Server Configuration

Change default port (8080):

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server.port=8989

5. Application Name

Set application name:

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spring.application.name=my-app

6. Database Configuration

MySQL Example

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spring.datasource.url=jdbc:mysql://localhost:3306/mydb
spring.datasource.username=root
spring.datasource.password=1234
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver

PostgreSQL Example

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spring.datasource.url=jdbc:postgresql://localhost:5432/mydb
spring.datasource.username=postgres
spring.datasource.password=1234

MongoDB Example

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spring.data.mongodb.uri=mongodb://localhost:27017/mydb

7. JPA (Hibernate) Configuration

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spring.jpa.hibernate.ddl-auto=update
spring.jpa.show-sql=true
spring.jpa.properties.hibernate.format_sql=true

8. Eureka Server Configuration

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eureka.client.service-url.defaultZone=http://localhost:8761/eureka/
eureka.client.register-with-eureka=true
eureka.client.fetch-registry=true

9. application.yml (Alternative)

YAML format is more readable for complex configurations.

Example

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server:
  port: 8989

spring:
  application:
    name: my-app
  datasource:
    url: jdbc:mysql://localhost:3306/mydb
    username: root
    password: 1234

10. Key Points

Properties file uses key-value format
YAML uses hierarchical structure
Both are used for configuration
YAML is preferred for large projects

11. Conclusion

application.properties is simple and widely used
application.yml is more readable for complex setups
Helps manage configuration without changing code