Search Suggest

Spring Boot - @ConfigurationProperties Example


In Spring Boot, the @ConfigurationProperties annotation allows us to map the resource files such as properties or YAML files to Java Bean object.
This annotation is applied to a class or a @Bean method in a @Configuration class to map or validate the external properties or YAML files.
This post shows how to use the @ConfigurationProperties in Spring Boot application.
Tools and technologies used for this application are -
  • Spring Boot 1.5.8.RELEASE
  • Java SE 1.8
  • Maven 3.5.2
  • Eclipse Neon.3 (4.6.3)
     

Using @ConfigurationProperties in Spring Boot

First, you need to define some properties in your application.properties file as follows.
myapp.mail.to=sunil@example.com
myapp.mail.host=mail.example.com
myapp.mail.port=250
Second, create a bean class with setter and getter methods and annotated it with @ConfigurationProperties as annotation.
@ConfigurationProperties(prefix="myapp.mail")
public class MailProperties {

private String to;
private String host;
private int port;

//Setter and getter methods
}
Third, register the @ConfigurationProperties bean in your @Configuration class using the @EnableConfigurationProperties annotation.
@Configuration
@EnableConfigurationProperties(MailProperties.class)
public class SpringBootApp {

}

Mapping collection or array in @ConfigurationProperties

To map collection or array in @ConfigurationProperties bean, you need to define the comma-separated values (properties) in your application.properties file.
myapp.mail.cc=mike@example.com,david@example.com
myapp.mail.bcc=sumit@example.com,admin@example.com
In your bean class, you can use the List or array of String to map collection properties as follows.
@ConfigurationProperties(prefix="myapp.mail")
public class MailProperties {

//...
private String[] cc;
private List<String> bcc;

//Setter and getter methods
}

Mapping nested properties in @ConfigurationProperties

To map the nested properties, first define the some properties in your application.properties file as follows.
myapp.mail.credential.user-name=sunil1234
myapp.mail.credential.password=xyz@1234
In your @ConfigurationProperties bean, create a nested bean with setter and getter methods as follows.
@ConfigurationProperties(prefix="myapp.mail")
public class MailProperties {

//...

private Credential credential = new Credential();

//...

public class Credential {

private String userName;
private String password;

//Setter and Getter methods

}

}

Validating @ConfigurationProperties

To validate the properties of a @ConfigurationProperties, first you need to add the validation-api and hibernate-validator dependencies in your classpath.
If you are using maven, add the following dependencies in your pom.xml file.
<dependency>
<groupId>org.hibernate.validator</groupId>
<artifactId>hibernate-validator</artifactId>
<version>6.0.5.Final</version>
</dependency>
<dependency>
<groupId>javax.validation</groupId>
<artifactId>validation-api</artifactId>
<version>2.0.0.Final</version>
</dependency>
Second, annotate the @ConfigurationProperties bean class with @Validated annotation to be validated by Spring Boot.
Use the javax.validation constraint annotations to validate the properties of the @ConfigurationProperties bean.
@ConfigurationProperties(prefix="myapp.mail")
@Validated
public class MailProperties {

@Email
private String to;
@NotBlank
private String host;
//...
//...
}
To validate the nested properties, you must annotate the associated field as @Valid to trigger its validation.
@ConfigurationProperties(prefix="myapp.mail")
@Validated
public class MailProperties {

//...

@Valid
private Credential credential = new Credential();

//...

public class Credential {
@NotBlank
private String userName;
@Size(max = 15, min = 6)
private String password;
//...
}

}

Complete Example

Open pom.xml file and add the following dependencies in it.  
pom.xml
<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>com.boraji.tutorial.springboot</groupId>
<artifactId>spring-boot-configuration-properties-example</artifactId>
<version>0.0.1-SNAPSHOT</version>
<name>Spring Boot Configuration Properties Example</name>
<properties>
<java.version>1.8</java.version>
</properties>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>1.5.8.RELEASE</version>
</parent>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter</artifactId>
</dependency>

<dependency>
<groupId>org.hibernate.validator</groupId>
<artifactId>hibernate-validator</artifactId>
<version>6.0.5.Final</version>
</dependency>
<dependency>
<groupId>javax.validation</groupId>
<artifactId>validation-api</artifactId>
<version>2.0.0.Final</version>
</dependency>

</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
</project>
application.properties
#Mapping single properties
myapp.mail.to=sunil@example.com
myapp.mail.host=mail.example.com
myapp.mail.port=250

#Mapping list or array
myapp.mail.cc=mike@example.com,david@example.com
myapp.mail.bcc=sumit@example.com,admin@example.com

#Mapping nested POJO class
myapp.mail.credential.user-name=sunil1234
myapp.mail.credential.password=xyz@1234
An equivalent YAML file will look like this -
application.yml
myapp: 
mail:
to: sunil@example.com
host: mail.example.com
port: 250
cc:
- mike@example.com
- david@example.com
bcc:
- sumit@example.com
- admin@example.com
credential:
user-name: sunil1234
password: xyz@1234
MailProperties.java
package com.boraji.tutorial.springboot.config;

import java.util.List;

import javax.validation.Valid;
import javax.validation.constraints.Email;
import javax.validation.constraints.NotBlank;
import javax.validation.constraints.Size;

import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.validation.annotation.Validated;

@ConfigurationProperties(prefix="myapp.mail")
@Validated
public class MailProperties {

@Email
private String to;
@NotBlank
private String host;
private int port;
private String[] cc;
private List<String> bcc;

@Valid
private Credential credential = new Credential();

//Setter and Getter methods

public class Credential {
@NotBlank
private String userName;
@Size(max = 15, min = 6)
private String password;

//Setter and Getter methods

}

}
Create a simple MailService.java file to print the MailProperties's properties as follows.
MailService.java
package com.boraji.tutorial.springboot.service;

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

import com.boraji.tutorial.springboot.config.MailProperties;

@Component
public class MailService {

@Autowired
private MailProperties mailProperties;

public void print() {
System.out.println("Mail TO = " + mailProperties.getTo());
System.out.println("HOST = " + mailProperties.getHost());
System.out.println("PORT = " + mailProperties.getPort());
System.out.println();

//Print list or array
System.out.println("Mail CC = " + String.join(", ", mailProperties.getCc()));
System.out.println("Mail BCC = " + mailProperties.getBcc());
System.out.println();

//Print nested bean's properties
System.out.println("User Name = " + mailProperties.getCredential().getUserName());
System.out.println("Password = " + mailProperties.getCredential().getPassword());
}
}
Create a main class to the test the @ConfigurationProperties bean.
SpringBootApp.java
package com.boraji.tutorial.springboot;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.context.properties.EnableConfigurationProperties;
import org.springframework.context.ApplicationContext;

import com.boraji.tutorial.springboot.config.MailProperties;
import com.boraji.tutorial.springboot.service.MailService;

@SpringBootApplication
@EnableConfigurationProperties(MailProperties.class)
public class SpringBootApp {

public static void main(String[] args) {
ApplicationContext context = SpringApplication.run(SpringBootApp.class, args);
MailService mailService = context.getBean(MailService.class);
mailService.print();
}

}
After running the SpringBootApp, your output will look like as follows.spring-boot-configurationproperties.png

Reference:



Đăng nhận xét