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Spring @PropertySource annotation tutorial

Spring @PropertySource annotation tutorial shows how to use @PropertySource annotation to include properties into the Environment and inject properties with @Value.

Spring is a popular Java application framework for creating enterprise applications.

Spring @PropertySource

@PropertySource is a convenient annotation for including PropertySource to Spring's Environment and allowing to inject properties via @Value into class attributes. (PropertySource is an object representing a set of property pairs from a particular source.)

@PropertySource is used together with @Configuration.

Spring @PropertySource example

The application uses Spring's @PropertySource to include properties from the application.properties file into the Environment and to inject them into class attributes.

pom.xml
src
├───main
│   ├───java
│   │   └───com
│   │       └───zetcode
│   │           │   Application.java
│   │           └───config
│   │                   AppConfig.java
│   └───resources
│           application.properties
│           logback.xml
└───test
    └───java

This is the project structure.

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.zetcode</groupId>
    <artifactId>propertysource</artifactId>
    <version>1.0-SNAPSHOT</version>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <maven.compiler.source>11</maven.compiler.source>
        <maven.compiler.target>11</maven.compiler.target>
        <spring-version>5.1.3.RELEASE</spring-version>

    </properties>

    <dependencies>

        <dependency>
            <groupId>ch.qos.logback</groupId>
            <artifactId>logback-classic</artifactId>
            <version>1.2.3</version>
        </dependency>

        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context</artifactId>
            <version>${spring-version}</version>
        </dependency>

        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-core</artifactId>
            <version>${spring-version}</version>
        </dependency> 
        
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.codehaus.mojo</groupId>
                <artifactId>exec-maven-plugin</artifactId>
                <version>1.6.0</version>
                <configuration>
                    <mainClass>com.zetcode.Application</mainClass>
                </configuration>
            </plugin>
        </plugins>
    </build>

</project>

In the pom.xml file, we have basic Spring dependencies spring-core, spring-context, and logging logback-classic dependency.

The exec-maven-plugin is used for executing Spring application from the Maven on the command line.

resources/logback.xml
<?xml version="1.0" encoding="UTF-8"?>
<configuration>
    <logger name="org.springframework" level="ERROR"/>
    <logger name="com.zetcode" level="INFO"/>

    <appender name="consoleAppender" class="ch.qos.logback.core.ConsoleAppender">
        <encoder>
            <Pattern>%d{HH:mm:ss.SSS} %blue(%-5level) %magenta(%logger{36}) - %msg %n
            </Pattern>
        </encoder>
    </appender>

    <root>
        <level value="INFO" />
        <appender-ref ref="consoleAppender" />
    </root>
</configuration>

The logback.xml is a configuration file for the Logback logging library.

resources/application.properties
app.name=My application
app.version=1.1

We have two properties in application.properties file.

com/zetcode/config/AppConfig.java
package com.zetcode.config;

import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.PropertySource;

@Configuration
@PropertySource(value = "application.properties", ignoreResourceNotFound = true)
public class AppConfig {

}

AppConfig is the application configuration class. The @PropertySource injects properties from the application.properties into the Spring's Environment.

com/zetcode/Application.java
package com.zetcode;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.core.env.Environment;

@ComponentScan(basePackages = "com.zetcode")
public class Application {

    private static final Logger logger = LoggerFactory.getLogger(Application.class);

    @Autowired
    private Environment env;

    @Value("${app.name}")
    private String appName;

    @Value("${app.version}")
    private String appVersion;

    public static void main(String[] args) {

        var ctx = new AnnotationConfigApplicationContext(Application.class);
        var app = ctx.getBean(Application.class);

        app.run();

        ctx.close();
    }

    private void run() {

        logger.info("From Environment");
        logger.info("Application name: {}", env.getProperty("app.name"));
        logger.info("Application version: {}", env.getProperty("app.version"));

        logger.info("Using @Value injection");
        logger.info("Application name: {}", appName);
        logger.info("Application version: {}", appVersion);
    }
}

In the Application, we get the properties using two methods.

@Autowired
private Environment env;

We inject the Environment. We can retrieve the properties with its getProperty() method.

@Value("${app.name}")
private String appName;

@Value("${app.version}")
private String appVersion;

We inject the properties with @Value annotation into the attributes.

logger.info("From Environment");
logger.info("Application name: {}", env.getProperty("app.name"));
logger.info("Application version: {}", env.getProperty("app.version"));

The first way to retrieve properties is from the Environment using the getProperty() method.

logger.info("Using @Value injection");
logger.info("Application name: {}", appName);
logger.info("Application version: {}", appVersion);

The second way is to use the injected attributes.

$ mvn -q exec:java
15:00:20.653 INFO  com.zetcode.Application - From Environment 
15:00:20.668 INFO  com.zetcode.Application - Application name: My application 
15:00:20.668 INFO  com.zetcode.Application - Application version: 1.1 
15:00:20.668 INFO  com.zetcode.Application - Using @Value injection 
15:00:20.668 INFO  com.zetcode.Application - Application name: My application 
15:00:20.668 INFO  com.zetcode.Application - Application version: 1.1 

We run the application.

In this tutorial, we have shown how to use @PropertySource annotation to conveniently work with properties in a Spring application.

You might also be interested in these related tutorials: Spring @Qualifier annotation tutorial, Spring @Configuration annotation tutorial, Spring context:property-placeholder tutorial, Java tutorial, or list all Spring tutorials.