Spring boot @ConfigurationProperties

Table of Contents

Maven dependencies:
Relaxed binding
Custom property file
Validation

In this tutorial, we are going to see about Spring boot @ConfigurationProperties annotation.

Spring boot @ConfigurationProperties allows you to map properties values with java object easily.

Let’s first see the normal mapping first. Let’s say you have properties file below.

application.properties


org.blogname=java2blog
org.host=hostEasy

org.blogname=java2blog

org.host=hostEasy

You can access above property file as below.


package org.arpit.java2blog;

import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;

@Component
public class BlogDetails {

    @Value("${org.blogName}")
    String blogName;

    @Value("${org.host}")
    String host;

    public String getBlogName() {
        return blogName;
    }

    public void setBlogName(String blogName) {
        this.blogName = blogName;
    }

    public String getHost() {
        return host;
    }

    public void setHost(String host) {
        this.host = host;
    }       
}

package org.arpit.java2blog;

import org.springframework.beans.factory.annotation.Value;

import org.springframework.stereotype.Component;

@Component

public class BlogDetails {

@Value("${org.blogName}")

String blogName;

@Value("${org.host}")

String host;

public String getBlogName() {

return blogName;

}

public void setBlogName(String blogName) {

this.blogName = blogName;

}

public String getHost() {

return host;

}

public void setHost(String host) {

this.host = host;

}

So, you can use @Value to get property value from application.properties but it might be tedious to use @Value everywhere,Spring boot provides @ConfigurationProperties to map properties value to java Object.

Let’s understand with the help of example.

Step 1: Create a dynamic web project using maven in eclipse named “SpringBootHelloWorldExample”.

Maven dependencies:

Step 2: Change pom.xml as below:


<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>org.arpit.java2blog</groupId>
    <artifactId>SpringBootConfigurationPropertiesExample</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>jar</packaging>

    <name>SpringBootConfigurationPropertiesExample</name>
    <description>Demo project for Spring Boot</description>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.0.3.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
        <java.version>1.8</java.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

</project>

<?xml version="1.0" encoding="UTF-8"?>

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">

<groupId>org.arpit.java2blog</groupId>

<artifactId>SpringBootConfigurationPropertiesExample</artifactId>

<version>0.0.1-SNAPSHOT</version>

<name>SpringBootConfigurationPropertiesExample</name>

<description>Demo project for Spring Boot</description>

<groupId>org.springframework.boot</groupId>

<artifactId>spring-boot-starter-parent</artifactId>

<version>2.0.3.RELEASE</version>

</parent>

<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>

<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>

<java.version>1.8</java.version>

</properties>

<groupId>org.springframework.boot</groupId>

<artifactId>spring-boot-starter</artifactId>

</dependency>

<groupId>org.springframework.boot</groupId>

<artifactId>spring-boot-starter-test</artifactId>

</dependency>

</dependencies>

<build>

<groupId>org.springframework.boot</groupId>

<artifactId>spring-boot-maven-plugin</artifactId>

</plugin>

</plugins>

</build>

</project>

step 3: Create a package named "org.arpit.java2blog" and class named ServerDetails


package org.arpit.java2blog;

import java.util.Arrays;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.context.annotation.Configuration;

@Configuration
@ConfigurationProperties(prefix="com.server")
public class ServerDetails {

    String url;
    String name;
    int[] port;
    Application application;

    public static class Application
    {
        String userName;
        String password;
        public String getUserName() {
            return userName;
        }
        public void setUserName(String userName) {
            this.userName = userName;
        }
        public String getPassword() {
            return password;
        }
        public void setPassword(String password) {
            this.password = password;
        }

    }

    public String getUrl() {
        return url;
    }

    public void setUrl(String url) {
        this.url = url;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int[] getPort() {
        return port;
    }

    public void setPort(int[] port) {
        this.port = port;
    }

    public Application getApplication() {
        return application;
    }

    public void setApplication(Application application) {
        this.application = application;
    }

    @Override
    public String toString() {
         return "Server Details{" +
                 "name='" + name + '\'' +
                 ", url='" + url + '\'' +
                 ", port='" + Arrays.toString(port) + '\'' +
                 ", username='" + application.getUserName()+ '\'' +
                 ", password='" + application.getPassword()+ '\'' +
                 '}';
    }   
}

package org.arpit.java2blog;

import java.util.Arrays;

import org.springframework.boot.context.properties.ConfigurationProperties;

import org.springframework.context.annotation.Configuration;

@Configuration

@ConfigurationProperties(prefix="com.server")

public class ServerDetails {

String url;

String name;

int[] port;

Application application;

public static class Application

{

String userName;

String password;

public String getUserName() {

return userName;

}

public void setUserName(String userName) {

this.userName = userName;

}

public String getPassword() {

return password;

}

public void setPassword(String password) {

this.password = password;

}

public String getUrl() {

return url;

}

public void setUrl(String url) {

this.url = url;

}

public String getName() {

return name;

}

public void setName(String name) {

this.name = name;

}

public int[] getPort() {

return port;

}

public void setPort(int[] port) {

this.port = port;

}

public Application getApplication() {

return application;

}

public void setApplication(Application application) {

this.application = application;

}

@Override

public String toString() {

return "Server Details{" +

"name='" + name + '\'' +

", url='" + url + '\'' +

", port='" + Arrays.toString(port) + '\'' +

", username='" + application.getUserName()+ '\'' +

", password='" + application.getPassword()+ '\'' +

'}';

}

step 4: Make changes to application.properties to add below properties.


org.blogName=java2blog
org.host=hostEasy

com.server.url= dummy.xyz.com
com.server.name= amazonEc2
com.server.port[0]=8080
com.server.port[1]=8081

com.server.application.username = admin
com.server.application.password = admin123

org.blogName=java2blog

org.host=hostEasy

com.server.url= dummy.xyz.com

com.server.name= amazonEc2

com.server.port[0]=8080

com.server.port[1]=8081

com.server.application.username = admin

com.server.application.password = admin123

step 5: Create Spring boot main class.


package org.arpit.java2blog;

import javax.annotation.PostConstruct;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.ConfigurableApplicationContext;

@SpringBootApplication
public class SpringBootExample {

    @Autowired
    ServerDetails serverDetails;

    public static void main(String[] args) {
        ConfigurableApplicationContext run = SpringApplication.run(SpringBootExample.class, args);
    }

    @PostConstruct
    public void init() {

        System.out.println(serverDetails.toString());

    }
}

package org.arpit.java2blog;

import javax.annotation.PostConstruct;

import org.springframework.beans.factory.annotation.Autowired;

import org.springframework.boot.SpringApplication;

import org.springframework.boot.autoconfigure.SpringBootApplication;

import org.springframework.context.ConfigurableApplicationContext;

@SpringBootApplication

public class SpringBootExample {

@Autowired

ServerDetails serverDetails;

public static void main(String[] args) {

ConfigurableApplicationContext run = SpringApplication.run(SpringBootExample.class, args);

}

@PostConstruct

public void init() {

System.out.println(serverDetails.toString());

}

As you can see, we have used @Autowired to inject ServerDetails to SpringBootExample.

Step 6: Run the application.

When you run above example, you will get below output.

. ____ _ __ _ _
/\\ / ___’_ __ _ _(_)_ __ __ _ \ \ \ \
( ( )\___ | ‘_ | ‘_| | ‘_ \/ _` | \ \ \ \
\\/ ___)| |_)| | | | | || (_| | ) ) ) )
‘ |____| .__|_| |_|_| |_\__, | / / / /
=========|_|==============|___/=/_/_/_/
:: Spring Boot :: (v2.0.3.RELEASE)

2018-07-14 23:53:47.766 INFO 67832 — [ main] org.arpit.java2blog.SpringBootExample : Starting SpringBootExample on apples-MacBook-Air.local with PID 67832 (/Users/apple/Downloads/SpringBootConfigurationPropertiesExample/target/classes started by apple in /Users/apple/Downloads/SpringBootConfigurationPropertiesExample)
2018-07-14 23:53:47.774 INFO 67832 — [ main] org.arpit.java2blog.SpringBootExample : No active profile set, falling back to default profiles: default
2018-07-14 23:53:47.901 INFO 67832 — [ main] s.c.a.AnnotationConfigApplicationContext : Refreshing org.springframework.context.annotation.AnnotationConfigApplicationContext@429bd883: startup date [Sat Jul 14 23:53:47 IST 2018]; root of context hierarchy
Server Details{name=’amazonEc2′, url=’dummy.xyz.com’, port='[8080, 8081]’, username=’admin’, password=’admin123′}
2018-07-14 23:53:49.000 INFO 67832 — [ main] o.s.j.e.a.AnnotationMBeanExporter : Registering beans for JMX exposure on startup
2018-07-14 23:53:49.024 INFO 67832 — [ main] org.arpit.java2blog.SpringBootExample : Started SpringBootExample in 2.252 seconds (JVM running for 3.406)
2018-07-14 23:53:49.028 INFO 67832 — [ Thread-2] s.c.a.AnnotationConfigApplicationContext : Closing org.springframework.context.annotation.AnnotationConfigApplicationContext@429bd883: startup date [Sat Jul 14 23:53:47 IST 2018]; root of context hierarchy
2018-07-14 23:53:49.030 INFO 67832 — [ Thread-2] o.s.j.e.a.AnnotationMBeanExporter : Unregistering JMX-exposed beans on shutdown

Here is the picture which will help you understand @ConfigurationProperties better.

Relaxed binding

One of the interesting feature of Spring boot is relaxed binding.
for com.server.application.username, below are valid spring boot bindings.

com.server.application.user_name(with _)
com.server.application.user-name(with -)
com.server.application.USER_NAME(with uppercase)

Custom property file

You can use custom property as well instead of application.property using @PropertySource annotation.


package org.arpit.java2blog;

import java.util.Arrays;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.context.annotation.Configuration;

@Configuration
@PropertySource("classpath:custom.properties")
@ConfigurationProperties(prefix="com.server")
public class ServerDetails {
..
}

package org.arpit.java2blog;

import java.util.Arrays;

import org.springframework.boot.context.properties.ConfigurationProperties;

import org.springframework.context.annotation.Configuration;

@Configuration

@PropertySource("classpath:custom.properties")

@ConfigurationProperties(prefix="com.server")

public class ServerDetails {

}

Validation

We can use JSR-303 Validation API to validate properties.You need to add below dependency.


<dependency>
    <groupId>org.hibernate</groupId>
   <artifactId>hibernate-validator</artifactId>
   <version>6.0.10.Final</version>
   <relativePath/>
</dependency>

<groupId>org.hibernate</groupId>

<artifactId>hibernate-validator</artifactId>

<version>6.0.10.Final</version>

</dependency>

For example:
Let’s say you want to restrict username from 5 to 8 characters, you can use @Length annotaton as below.


          @Length(max = 8, min = 5)
        String userName;

@Length(max = 8, min = 5)

String userName;

If you change userName to adam


com.server.application.username = adam

com.server.application.username = adam

You will get below validation error.

Property:.com.server.application.username
Value: adam
Reason: length must be between 5 and 8

Download source code SpringBootConfigurationPropertiesExample

That’s all about Spring boot @ConfigurationProperties.

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Spring boot @ConfigurationProperties

Maven dependencies:

Relaxed binding

Custom property file

Validation

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