Oppiskele Best Practices for Organizing Properties Files

As your Java projects become more complex, the way you organize your properties files can greatly affect both maintainability and scalability. Well-structured configuration files make it easier to manage changes, onboard new team members, and avoid costly mistakes in production. Following a few best practices can help you stay organized as your application grows.

Guidelines for Naming Conventions

Use clear, descriptive names that indicate the purpose or scope of the configuration;
Include the environment name in the file if it is environment-specific, such as application-dev.properties, application-prod.properties;
Avoid generic names like config.properties unless used for a specific, well-understood global configuration.

Directory Structure

Store all properties files in a dedicated configuration directory, such as src/main/resources/config or src/main/resources/properties;
Group related properties files by module or feature if your project is modular;
Keep environment-specific files together for easier management and deployment.

Separating Environment-Specific Configurations

Create separate properties files for each environment (development, testing, production);
Avoid hardcoding environment-specific values in your main configuration;
Use naming conventions and directory structure to clearly distinguish between environments.

Organizing your properties files with these strategies helps prevent accidental configuration leaks, reduces merge conflicts, and simplifies automated deployments.

Main.java

src/main/resources/application-dev.properties

src/main/resources/application-prod.properties


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package com.example;

import java.io.FileInputStream;
import java.io.IOException;
import java.util.Properties;

public class Main {
    public static void main(String[] args) {
        String env = System.getProperty("env", "dev"); // default to "dev"
        String filename = "src/main/resources/application-" + env + ".properties";
        Properties props = new Properties();
        try (FileInputStream fis = new FileInputStream(filename)) {
            props.load(fis);
            System.out.println("Loaded properties for environment: " + env);
            System.out.println("app.name = " + props.getProperty("app.name"));
            System.out.println("app.version = " + props.getProperty("app.version"));
        } catch (IOException e) {
            System.err.println("Could not load properties file: " + filename);
        }
    }
}

When working with properties files in a team or across multiple environments, version control becomes a critical consideration. You should always add your configuration files to version control, but never include sensitive information such as passwords or API keys in these files. Instead, store secrets in separate files (like application-secrets.properties) that are excluded from version control using .gitignore or equivalent. This approach prevents accidental leaks of confidential data while still allowing your team to share and track non-sensitive configuration changes. Additionally, document which files are excluded and provide sample templates (for example, application-secrets.properties.example) so that new developers know what values are needed.

Main.java

src/main/resources/application-base.properties

src/main/resources/application-dev.properties

src/main/resources/application-prod.properties


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// File: Main.java
package com.example;

import java.io.FileInputStream;
import java.io.IOException;
import java.util.Properties;

public class Main {
    public static void main(String[] args) {
        String env = System.getProperty("env", "dev");
        String baseFile = "src/main/resources/application-base.properties";
        String envFile = "src/main/resources/application-" + env + ".properties";
        Properties props = new Properties();
        try (FileInputStream fisBase = new FileInputStream(baseFile)) {
            props.load(fisBase);
        } catch (IOException e) {
            System.err.println("Could not load base properties: " + baseFile);
        }
        try (FileInputStream fisEnv = new FileInputStream(envFile)) {
            props.load(fisEnv); // overrides base where keys match
        } catch (IOException e) {
            System.err.println("Could not load environment properties: " + envFile);
        }
        System.out.println("Final configuration:");
        props.forEach((k, v) -> System.out.println(k + " = " + v));
    }
}

1. Why is it important to separate environment-specific properties files?

2. What is a recommended practice for handling sensitive information in properties files?

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Guidelines for Naming Conventions

Use clear, descriptive names that indicate the purpose or scope of the configuration;
Include the environment name in the file if it is environment-specific, such as application-dev.properties, application-prod.properties;
Avoid generic names like config.properties unless used for a specific, well-understood global configuration.

Directory Structure

Store all properties files in a dedicated configuration directory, such as src/main/resources/config or src/main/resources/properties;
Group related properties files by module or feature if your project is modular;
Keep environment-specific files together for easier management and deployment.

Separating Environment-Specific Configurations

Create separate properties files for each environment (development, testing, production);
Avoid hardcoding environment-specific values in your main configuration;
Use naming conventions and directory structure to clearly distinguish between environments.

Organizing your properties files with these strategies helps prevent accidental configuration leaks, reduces merge conflicts, and simplifies automated deployments.

Main.java

src/main/resources/application-dev.properties

src/main/resources/application-prod.properties


              123456789101112131415161718192021
            
package com.example;

import java.io.FileInputStream;
import java.io.IOException;
import java.util.Properties;

public class Main {
    public static void main(String[] args) {
        String env = System.getProperty("env", "dev"); // default to "dev"
        String filename = "src/main/resources/application-" + env + ".properties";
        Properties props = new Properties();
        try (FileInputStream fis = new FileInputStream(filename)) {
            props.load(fis);
            System.out.println("Loaded properties for environment: " + env);
            System.out.println("app.name = " + props.getProperty("app.name"));
            System.out.println("app.version = " + props.getProperty("app.version"));
        } catch (IOException e) {
            System.err.println("Could not load properties file: " + filename);
        }
    }
}

Main.java

src/main/resources/application-base.properties

src/main/resources/application-dev.properties

src/main/resources/application-prod.properties


              12345678910111213141516171819202122232425262728
            
// File: Main.java
package com.example;

import java.io.FileInputStream;
import java.io.IOException;
import java.util.Properties;

public class Main {
    public static void main(String[] args) {
        String env = System.getProperty("env", "dev");
        String baseFile = "src/main/resources/application-base.properties";
        String envFile = "src/main/resources/application-" + env + ".properties";
        Properties props = new Properties();
        try (FileInputStream fisBase = new FileInputStream(baseFile)) {
            props.load(fisBase);
        } catch (IOException e) {
            System.err.println("Could not load base properties: " + baseFile);
        }
        try (FileInputStream fisEnv = new FileInputStream(envFile)) {
            props.load(fisEnv); // overrides base where keys match
        } catch (IOException e) {
            System.err.println("Could not load environment properties: " + envFile);
        }
        System.out.println("Final configuration:");
        props.forEach((k, v) -> System.out.println(k + " = " + v));
    }
}

1. Why is it important to separate environment-specific properties files?

2. What is a recommended practice for handling sensitive information in properties files?

Oliko kaikki selvää?

Kiitos palautteestasi!

Osio 1. Luku 5