Spring Boot @ConfigurationProperties
last modified July 18, 2023
Spring Boot @ConfigurationProperties tutorial shows how to bind properties to an object with @ConfigurationProperties in a Spring Boot application.
Spring is a popular Java application framework and Spring Boot is an evolution of Spring that helps create stand-alone, production-grade Spring based applications easily.
@ConfigurationProperties
@ConfigurationProperties allows to map the entire Properties and
Yaml files into an object easily. It also allows to validate properties with
JSR-303 bean validation. By default, the annotation reads from the
application.properties file. The source file can be changed with
@PropertySource annotation.
Spring Boot @ConfigurationProperties example
The following application reads configuration data from the
application.properties file, which is the default
Spring Boot configuration file.
build.gradle
...
src
├───main
│ ├───java
│ │ └───com
│ │ └───zetcode
│ │ │ Application.java
│ │ │ MyRunner.java
│ │ └───conf
│ │ AppProperties.java
│ └───resources
│ application.properties
└───test
└───java
This is the project structure.
plugins {
id 'org.springframework.boot' version '3.1.1'
id 'io.spring.dependency-management' version '1.1.0'
id 'java'
}
group = 'com.zetcode'
version = '0.0.1-SNAPSHOT'
sourceCompatibility = '17'
repositories {
mavenCentral()
}
dependencies {
implementation 'org.springframework.boot:spring-boot-starter'
}
This is the build.gradle file.
spring.main.banner-mode=off app.colour=steelblue app.lang=en app.theme=dark
In the application.properties file we have three custom properties.
They have the app prefix.
package com.zetcode.conf;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.context.annotation.Configuration;
@Configuration
@ConfigurationProperties(prefix = "app")
public class AppProperties {
private String colour;
private String lang;
private String theme;
public String getColour() {
return colour;
}
public void setColour(String colour) {
this.colour = colour;
}
public String getLang() {
return lang;
}
public void setLang(String lang) {
this.lang = lang;
}
public String getTheme() {
return theme;
}
public void setTheme(String theme) {
this.theme = theme;
}
}
The properties are going to be bind to this configuration object.
@Configuration
@ConfigurationProperties(prefix = "app")
public class AppProperties {
The @Configuration annotation makes it a Spring-managed bean.
In the @ConfigurationProperties, we set the prefix for our
properties.
package com.zetcode;
import com.zetcode.conf.AppProperties;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.CommandLineRunner;
import org.springframework.stereotype.Component;
@Component
public class MyRunner implements CommandLineRunner {
private static final Logger logger = LoggerFactory.getLogger(Application.class);
private final AppProperties appProperties;
@Autowired
public MyRunner(AppProperties appProperties) {
this.appProperties = appProperties;
}
@Override
public void run(String... args) throws Exception {
logger.info("Colour: {}", appProperties.getColour());
logger.info("Language: {}", appProperties.getLang());
logger.info("Theme: {}", appProperties.getTheme());
}
}
In the MyRunner, we inject the AppProperties into a
field and read its values.
package com.zetcode;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
@SpringBootApplication
public class Application {
public static void main(String[] args) {
SpringApplication.run(Application.class, args);
}
}
Application is the entry point which sets up Spring Boot
application.
Spring Boot @ConfigurationProperties example II
In the second application, we will also validate the properties.
build.gradle
...
src
├───main
│ ├───java
│ │ └───com
│ │ └───zetcode
│ │ │ Application.java
│ │ │ MyRunner.java
│ │ └───conf
│ │ MailProperties.java
│ └───resources
│ application.properties
│ mail.properties
└───test
└───java
This is the project structure.
plugins {
id 'org.springframework.boot' version '3.1.1'
id 'io.spring.dependency-management' version '1.1.0'
id 'java'
}
group = 'com.zetcode'
version = '0.0.1-SNAPSHOT'
sourceCompatibility = '17'
repositories {
mavenCentral()
}
dependencies {
implementation 'org.springframework.boot:spring-boot-starter'
implementation 'org.hibernate.validator:hibernate-validator'
}
This is the build.gradle file. We have an additional
hibernate-validator dependency.
spring.main.banner-mode=off
This is the application.properties file.
hostname=info@example.com port=9000 from=admin@example.com recipients[0]=user1@example.com recipients[1]=user2@example.com recipients[2]=user3@example.com recipients[3]=user4@example.com
We have a custom mail.properties file.
package com.zetcode.conf;
import jakarta.validation.constraints.Max;
import jakarta.validation.constraints.Min;
import jakarta.validation.constraints.NotNull;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.PropertySource;
import org.springframework.validation.annotation.Validated;
import java.util.List;
@Configuration
@PropertySource("classpath:mail.properties")
@ConfigurationProperties
@Validated
public class MailProperties {
@NotNull
private String hostname;
@Min(1000)
@Max(10000)
private int port;
@NotNull
private String from;
@NotNull
private List>String> recipients;
public String getHostname() {
return hostname;
}
public void setHostname(String hostname) {
this.hostname = hostname;
}
public int getPort() {
return port;
}
public void setPort(int port) {
this.port = port;
}
public String getFrom() {
return from;
}
public void setFrom(String from) {
this.from = from;
}
public List>String> getRecipients() {
return recipients;
}
public void setRecipients(List>String> recipients) {
this.recipients = recipients;
}
}
We use the @PropertySource annotation set the path to the
custom properties file. The @Validated annotation validates
the properties.
package com.zetcode;
import com.zetcode.conf.MailProperties;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.CommandLineRunner;
import org.springframework.stereotype.Component;
@Component
public class MyRunner implements CommandLineRunner {
private static final Logger logger = LoggerFactory.getLogger(Application.class);
private final MailProperties mailProperties;
@Autowired
public MyRunner(MailProperties mailProperties) {
this.mailProperties = mailProperties;
}
@Override
public void run(String... args) throws Exception {
logger.info("Hostname: {}", mailProperties.getHostname());
logger.info("Port: {}", mailProperties.getPort());
logger.info("From: {}", mailProperties.getFrom());
logger.info("Recipients: {}", mailProperties.getRecipients());
}
}
We inject the MailProperties and read them in the run
method.
package com.zetcode;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
@SpringBootApplication
public class Application {
public static void main(String[] args) {
SpringApplication.run(Application.class, args);
}
}
This is the Application class.
We run the application with ./gradlew bootRun.
In this article we have shown how to use @ConfigurationProperties
to read configuration properties from an external file.
