How to Use Multiple Properties Files in Spring Boot

In Spring Boot, you can use multiple properties files by specifying them with @PropertySource annotations or by listing them in spring.config.import in application.properties. This allows your application to load configuration from several files and merge them automatically.

Syntax

You can load multiple properties files in Spring Boot using the @PropertySource annotation on a configuration class or by using the spring.config.import property in your application.properties or application.yml.

@PropertySource syntax:

• @PropertySource({"classpath:file1.properties", "classpath:file2.properties"}) loads multiple files.

spring.config.import syntax:

• spring.config.import=classpath:file1.properties,classpath:file2.properties

java

@Configuration
@PropertySource({"classpath:config1.properties", "classpath:config2.properties"})
public class AppConfig {
    // Beans and configuration
}

Example

This example shows how to load two properties files named config1.properties and config2.properties using @PropertySource. The properties from both files are available for injection using @Value or Environment.

java

package com.example.demo;

import org.springframework.beans.factory.annotation.Value;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.PropertySource;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

@SpringBootApplication
@PropertySource({"classpath:config1.properties", "classpath:config2.properties"})
public class DemoApplication {
    public static void main(String[] args) {
        SpringApplication.run(DemoApplication.class, args);
    }
}

@RestController
class MyController {

    @Value("${app.name}")
    private String appName;

    @Value("${app.version}")
    private String appVersion;

    @GetMapping("/info")
    public String info() {
        return "App: " + appName + ", Version: " + appVersion;
    }
}

Output

App: MySpringApp, Version: 1.0.1

Common Pitfalls

1. Missing files: If a properties file is not found, Spring throws an error unless you set ignoreResourceNotFound=true in @PropertySource.

2. Property overriding: Properties in later files override earlier ones. Order matters.

3. Using @PropertySource only works with .properties files, not .yml.

4. For YAML files, use spring.config.import in application.properties or application.yml.

java

@PropertySource(value = "classpath:optional.properties", ignoreResourceNotFound = true)
// This prevents errors if the file is missing

Quick Reference

Feature	Usage	Notes
@PropertySource	Load multiple .properties files in config class	Only supports .properties, not YAML
spring.config.import	List multiple config files in application.properties	Supports .properties and .yml files
ignoreResourceNotFound	Avoid errors if file missing	Use in @PropertySource annotation
Property overriding	Last file properties override earlier ones	Order matters in loading files

Key Takeaways

Use @PropertySource to load multiple .properties files in a configuration class.

Use spring.config.import in application.properties to load multiple config files including YAML.

Order of files matters; later files override earlier properties.

Set ignoreResourceNotFound=true in @PropertySource to avoid errors if files are missing.

For YAML files, prefer spring.config.import over @PropertySource.