7 Ways to Load Property Files in Spring Boot 3.2.5

1. Introduction

In Spring Boot, property files externalize configuration, allowing centralized management of settings such as database connections, logging, or custom parameters across environments.

This article explores seven methods to load property files in Spring Boot.

2. Practical Cases

2.1 Loading property files in Spring Boot

Spring Boot can obtain properties from multiple locations in the following order:

External application.properties / application.yml

Internal application.properties / application.yml

Operating system environment variables

Java system properties

Command‑line arguments

When a profile is active, Spring Boot also loads profile‑specific files such as application-{profile}.properties , which have higher precedence.

2.2 Loading external property files

By default Spring Boot searches src/main/resources for application.properties . You can override the location with the spring.config.location property, e.g.

<code>java -jar myapp.jar --spring.config.location=/home/app/application.properties</code>

Alternatively, place the file in a classpath directory (e.g., config/ ) and use spring.config.additional-location=classpath:/config/ .

2.3 Loading the default application.properties

Spring Boot automatically loads application.properties or application.yml from src/main/resources . Example entries:

<code>spring.datasource.url=jdbc:mysql://localhost/mydb
spring.datasource.username=root
spring.datasource.password=xxxooo</code>

2.4 Loading profile‑specific property files

Files named application-{profile}.properties are used when the profile is activated, e.g.

<code>java -jar myapp.jar --spring.profiles.active=prod</code>

This loads properties from application-prod.properties .

2.5 Loading custom property files

Use @PropertySource to import additional files:

<code>@Configuration
@PropertySource("classpath:pack.properties")
public class CustomConfiguration {
    @Value("${pack.app.title}")
    private String title;
}</code>

Multiple files can be loaded with @PropertySources .

2.6 Overriding properties with environment variables

Set an environment variable to replace a property, e.g.

<code>export SPRING_DATASOURCE_URL=jdbc:mysql://localhost/mydb</code>

2.7 Overriding properties with system properties

Use JVM arguments to set system properties, which have higher precedence than environment variables:

<code>java -jar myapp.jar -Dspring.datasource.url=jdbc:mysql://localhost/mydb</code>