Injecting Properies in Spring boot

In this tutorial, we will find how to bind configuration properties to Structured Object.

Spring Boot allows you to externalize your configuration so you can work with the same application code in different environments. If these configurations are all related then we can bound these to java object using spring's @ConfigurationProperties annotation.

Ways to make configuration object injected into application

• Annotate Application class with @EnableConfigurationProperties(value=MyProperties.class). In this case, there is no need to mark your configuration object with @Component annotation.
• Or mark your configuration object with @Component annotation. This will make your class to be picked up by Spring's component scanner.

Find this project on Github

https://github.com/javacodenet/spring-boot-injecting-properties

pom.xml

	<?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>com.javacodenet</groupId>
	<artifactId>spring-boot</artifactId>
	<version>1.0-SNAPSHOT</version>
	<parent>
	<groupId>org.springframework.boot</groupId>
	<artifactId>spring-boot-starter-parent</artifactId>
	<version>1.4.0.RELEASE</version>
	</parent>
	<dependencies>
	<dependency>
	<groupId>org.springframework.boot</groupId>
	<artifactId>spring-boot-starter-web</artifactId>
	</dependency>
	</dependencies>
	<build>
	<plugins>
	<plugin>
	<groupId>org.springframework.boot</groupId>
	<artifactId>spring-boot-maven-plugin</artifactId>
	</plugin>
	</plugins>
	</build>
	</project>

view raw pom.xml hosted with ❤ by GitHub

Application.java

	package com.javacodenet;
	import org.springframework.beans.factory.annotation.Autowired;
	import org.springframework.beans.factory.annotation.Value;
	import org.springframework.boot.SpringApplication;
	import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
	import org.springframework.boot.autoconfigure.SpringBootApplication;
	import org.springframework.boot.context.properties.EnableConfigurationProperties;
	import org.springframework.web.bind.annotation.RequestMapping;
	import org.springframework.web.bind.annotation.RestController;
	@RestController
	@SpringBootApplication
	//@EnableConfigurationProperties(value=MyProperties.class) This will be required if you remove @Component annotation
	// from MyProperties.java
	public class Application {
	@Autowired
	MyProperties myProperties;
	@Autowired
	CustomProperties customProperties;
	@RequestMapping("/")
	public String myMessageProperty() {
	return "Value read from application.properties is: " + myProperties.getMessageProperty() + " " +
	"And value read from custom.properties is: " + customProperties.getCustomMessageProperty();
	}
	public static void main(String[] args) {
	SpringApplication.run(Application.class, args);
	}
	}

view raw Application.java hosted with ❤ by GitHub

MyProperties.java

Reads properties from application.properties.

	package com.javacodenet;
	import org.springframework.boot.context.properties.ConfigurationProperties;
	import org.springframework.stereotype.Component;
	@Component
	@ConfigurationProperties(prefix = "my")
	public class MyProperties {
	private String messageProperty;
	public String getMessageProperty() {
	return messageProperty;
	}
	public void setMessageProperty(String messageProperty) {
	this.messageProperty = messageProperty;
	}
	}

view raw MyProperties.java hosted with ❤ by GitHub

CustomProperties.java

Reads properties from custom.properties. We specified the location of the file as classpath along with its name.

	package com.javacodenet;
	import org.springframework.boot.context.properties.ConfigurationProperties;
	import org.springframework.stereotype.Component;
	@Component
	@ConfigurationProperties(prefix = "my", locations = "classpath:custom.properties")
	public class CustomProperties {
	private String customMessageProperty;
	public String getCustomMessageProperty() {
	return customMessageProperty;
	}
	public void setCustomMessageProperty(String customMessageProperty) {
	this.customMessageProperty = customMessageProperty;
	}
	}

view raw CustomProperties.java hosted with ❤ by GitHub

application.properties

	#my is the prefix and MESSAGE_PROPERTY is the final node
	my.MESSAGE_PROPERTY="Message Property"
	#Following are the different ways of defining your properties
	#my.messageProperty="Message Property"
	#my.message-property="Message Property"

view raw application.properties hosted with ❤ by GitHub

custom.properties

my.CUSTOM_MESSAGE_PROPERTY="Custom Message Property"

view raw custom.properties hosted with ❤ by GitHub

Output