Loading List from Properties file with spring @Value

This example shows you how to load a list from a properties file using the @Value annotation. In this tutorial we’ll be using the comma as a separator. But you can use any delimiter you want.

Spring @Value Loading List from Properties

We can load a list from a properties file by annotating the field with the @Value annotation. And providing the property name of the resource. The PropertySourcesPlaceholderConfigurer is used to resolve the ${} in the expression. We can manipulate the property with the split() method.

package com.memorynotfound.spring.core;

import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.PropertySource;
import org.springframework.context.support.PropertySourcesPlaceholderConfigurer;
import java.util.List;

@Configuration
@PropertySource(value="classpath:application.properties")
public class AppConfig {

    @Value("#{'${planets.names}'.split(',')}")
    private List<String> planets;

    @Bean
    public static PropertySourcesPlaceholderConfigurer propertySourcesPlaceholderConfigurer() {
        return new PropertySourcesPlaceholderConfigurer();
    }

    public List<String> getPlanets() {
        return planets;
    }

}

Properties File

We registered one property planets.names in the application.properties file. This file is located on the class path.

planets.names=Sun,Mercury,Venus,Earth,Mars,Jupiter,Saturn,Uranus,Neptune

Running The Application

We bootstrap the application and retrieve the AppConfig class. Afterwards we print the values to the console.

package com.memorynotfound.spring.core;

import org.springframework.context.ApplicationContext;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class Run {

    public static void main(String... args){
        ApplicationContext context = new AnnotationConfigApplicationContext(AppConfig.class);
        AppConfig appConfig = context.getBean(AppConfig.class);
        System.out.println("planets: " + appConfig.getPlanets());
    }
}

Output

The previous code will produce the following output.

Planets: [Sun, Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune]

References

• PropertySourcesPlaceholderConfigurer JavaDoc
• @PropertySource JavaDoc
• @Value JavaDoc

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