How to Read config.properties value using Spring MVC ‘singleton’ Scope in Java?

Sometime back I have written a tutorial on how to read config file in tradition way. But what if you want to load it as a Spring MVC framework?

It is most common that you may need to access some of your config.properties values all the time in your Java class. There is a simple way to get it using Spring MVC’s singleton scope.

Kindly take a look at below complete workspace picture.

We need to create 4 files:

1. CrunchifySpringExample.java under package com.crunchify.tutorial
2. config.properties file under /resources/config/ folder
3. spring-bean.xml file under /resources folder
4. pom.xml file (convert project to Maven project)

Let’s get started:

Step-1

Create Dynamic Web Project called CrunchifyLoadPropertiesSpringMVC

Step-2

Convert project to Maven Project.

This will create pom.xml file and we will add Spring dependancies.

Step-3

Create file CrunchifySpringExample.java

package com.crunchify.tutorial;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.Scope;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import org.springframework.stereotype.Component;

/**
 * 
 * @author Crunchify.com
 */

@Component("crunchifySpringExample")
@Scope("singleton")
public class CrunchifySpringExample {

    private static boolean springExample;
    private static String springTutorial;
    private static String url;

    @Autowired
    public CrunchifySpringExample(@Value("${CRUNCHIFY_URL}") String url, @Value("${SPRING_TUTORIAL}") String springTutorial,
            @Value("${IS_THIS_SPRING_EXAMPLE}") boolean springExample) {
        CrunchifySpringExample.springExample = springExample;
        CrunchifySpringExample.springTutorial = springTutorial;
        CrunchifySpringExample.url = url;

    }

    @SuppressWarnings({ "resource", "unused" })
    public static void main(String[] args) {
        try {
            ClassPathXmlApplicationContext ctx = new ClassPathXmlApplicationContext(new String[] { "spring-bean.xml" });
        } catch (Throwable e) {
            System.out.println(e);
        }

        System.out.println("\nLoading Properties from Config File during application startup: \n\nSPRING_TUTORIAL: " + springTutorial);
        System.out.println("IS_THIS_SPRING_EXAMPLE: " + springExample);
        System.out.println("CRUNCHIFY_URL: " + url);
    }

}

Step-4

Here is my pom.xml file.

<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>CrunchifyLoadPropertiesSpringMVC</groupId>
    <artifactId>CrunchifyLoadPropertiesSpringMVC</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>war</packaging>
    <name>CrunchifyLoadPropertiesSpringMVC</name>
    <build>
        <sourceDirectory>src</sourceDirectory>
        <plugins>
            <plugin>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>3.1</version>
                <configuration>
                    <source>1.7</source>
                    <target>1.7</target>
                </configuration>
            </plugin>
            <plugin>
                <artifactId>maven-war-plugin</artifactId>
                <version>2.3</version>
                <configuration>
                    <warSourceDirectory>WebContent</warSourceDirectory>
                    <failOnMissingWebXml>false</failOnMissingWebXml>
                </configuration>
            </plugin>
        </plugins>
    </build>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <spring.version>4.0.2.RELEASE</spring.version>
    </properties>

    <dependencies>

        <!-- Spring base -->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-aop</artifactId>
            <version>${spring.version}</version>
            <exclusions>
                <exclusion>
                    <groupId>commons-logging</groupId>
                    <artifactId>commons-logging</artifactId>
                </exclusion>
            </exclusions>
        </dependency>
        <!-- Spring MVC -->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-webmvc</artifactId>
            <version>${spring.version}</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-web</artifactId>
            <version>${spring.version}</version>
        </dependency>
        <dependency>
            <groupId>commons-logging</groupId>
            <artifactId>commons-logging</artifactId>
            <version>1.1.1</version>
        </dependency>
    </dependencies>
</project>

Step-5

If you don’t see “resources” folder. create one.

Step-6

Create config.properties file with below contents.

# Crunchify Properties
IS_THIS_SPRING_EXAMPLE=true
SPRING_TUTORIAL=CRUNCHIFY_TUTORIAL
CRUNCHIFY_URL=https://crunchify.com

Step-7

Content of spring-bean.xml file

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:util="http://www.springframework.org/schema/util" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:context="http://www.springframework.org/schema/context"
    xsi:schemaLocation="
       http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
       http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util-3.0.xsd 
       http://www.springframework.org/schema/context
       http://www.springframework.org/schema/context/spring-context-3.0.xsd">

    <util:properties id="nodeProperty"
        location="classpath:config/config.properties" />
    <context:property-placeholder
        properties-ref="nodeProperty" />
    <context:component-scan base-package="com.crunchify.tutorial" />
</beans>

Step-8

Now run CrunchifySpringExample.java and you should see result like this.

Step-9

Output

Jul 05, 2014 3:38:52 PM org.springframework.context.support.AbstractApplicationContext prepareRefresh
INFO: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@7e3bfb66: startup date [Sat Jul 05 15:38:52 CDT 2014]; root of context hierarchy
Jul 05, 2014 3:38:52 PM org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions
INFO: Loading XML bean definitions from class path resource [spring-bean.xml]
Jul 05, 2014 3:38:52 PM org.springframework.core.io.support.PropertiesLoaderSupport loadProperties
INFO: Loading properties file from class path resource [config/config.properties]

Loading Properties from Config File during application startup: 

SPRING_TUTORIAL: CRUNCHIFY_TUTORIAL
IS_THIS_SPRING_EXAMPLE: true
CRUNCHIFY_URL: https://crunchify.com

Enjoy and Happy Coding..

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