Spring ResourceLoaderAware example | Spring Tutorial | Spring Framework | Spring basics

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Overview: ResourceLoaderAware in Spring

In the Spring Framework, applications frequently need to load external resources such as text files, XML configurations, or images from the classpath, file system, or web URLs. While Spring's ApplicationContext implements the ResourceLoader interface directly, a bean can obtain a reference to this loader cleanly during its lifecycle by implementing the ResourceLoaderAware interface.

In this guide, you will learn how the ResourceLoaderAware interface works, how Spring injects the ResourceLoader instance, and how to use it to load external resources easily.

Understanding ResourceLoaderAware

The ResourceLoaderAware interface is part of Spring's set of "Aware" callback interfaces:

• Lifecycle Callback: When a bean implements ResourceLoaderAware, Spring automatically invokes its setResourceLoader(ResourceLoader resourceLoader) method during bean initialization.
• Unified Resource Access: The injected ResourceLoader provides the getResource(location) method, supporting prefixes like classpath:, file:, and standard URLs.
• No Direct ApplicationContext Coupling: It grants your bean the ability to load external resources without requiring full access to the broader ApplicationContext.

Step-by-Step Implementation

1. Implement the Interface: Have your bean class implement org.springframework.context.ResourceLoaderAware.
2. Override setResourceLoader(): Store the passed ResourceLoader reference in a member field:
   public void setResourceLoader(ResourceLoader resourceLoader) {
  this.resourceLoader = resourceLoader;
}
3. Load Resources: Use the resourceLoader.getResource("classpath:sample.txt") method to retrieve and process files seamlessly.

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---

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Spring ResourceLoaderAware example | Spring Tutorial | Spring Framework | Spring basics

Spring ResourceLoaderAware example | Spring Tutorial | Spring Framework | Spring basics

Spring ResourceLoaderAware example | Spring Tutorial | Spring Framework | Spring basics

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%20http://maven.apache.org/maven-v4_0_0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <groupId>com.ram.core</groupId>
    <artifactId>SpringDemo</artifactId>
    <packaging>jar</packaging>
    <version>1.0-SNAPSHOT</version>
    <name>SpringDemo</name>
    <url>http://maven.apache.org</url>

    <properties>
        <spring.version>5.0.2.RELEASE</spring.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>3.8.1</version>
            <scope>test</scope>
        </dependency>

        <!-- Spring 5 dependencies -->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-core</artifactId>
            <version>${spring.version}</version>
        </dependency>

        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context</artifactId>
            <version>${spring.version}</version>
        </dependency>
    </dependencies>
 
     <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>3.7.0</version>
                <configuration>
                    <source>1.8</source>
                    <target>1.8</target>
                </configuration>
            </plugin>
        </plugins>
    </build>
 
</project>

names.txt

Peter
Ram
Juli

ResourceLoaderAwareImpl.java

package com.ram.aware;

import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;

import org.springframework.context.ResourceLoaderAware;
import org.springframework.core.io.Resource;
import org.springframework.core.io.ResourceLoader;

public class ResourceLoaderAwareImpl implements ResourceLoaderAware
{

    private ResourceLoader resourceLoader;

    public void setResourceLoader(ResourceLoader resourceLoader)
    {

        System.out.println(
                "setResourceLoader(ResourceLoader resourceLoader) is called "
                        + "by the Spring Container");
        this.resourceLoader = resourceLoader;

    }

    public void displayFileInfo()
    {
        Resource resource = resourceLoader.getResource("classpath:names.txt");

        try (
                BufferedReader br = new BufferedReader(
                        new FileReader(resource.getFile().getPath())))
        {

            String thisLine = null;

            System.out.println("Names from the files are..");
            while ((thisLine = br.readLine()) != null)
            {
                System.out.println(thisLine);
            }

        }
        catch (FileNotFoundException e)
        {
            e.printStackTrace();
        }
        catch (IOException e)
        {
            e.printStackTrace();
        }

    }
}

applicationContext.xml

<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans-4.3.xsd">

    <bean id="resourceLoaderAware" class="com.ram.aware.ResourceLoaderAwareImpl" />

</beans>

App.java

package com.ram.core;

import org.springframework.context.support.ClassPathXmlApplicationContext;

import com.ram.aware.ResourceLoaderAwareImpl;

public class App
{
    public static void main(String[] args)
    {
        ClassPathXmlApplicationContext applicationContext = new ClassPathXmlApplicationContext(
                "applicationContext.xml");

        ResourceLoaderAwareImpl resourceLoaderAwareImpl = applicationContext
                .getBean("resourceLoaderAware", ResourceLoaderAwareImpl.class);

        System.out.println("resourceLoaderAwareImpl = "+resourceLoaderAwareImpl);
     
        resourceLoaderAwareImpl.displayFileInfo();
     
        applicationContext.close();
    }
}

Output

Aug 13, 2018 9:46:49 AM org.springframework.context.support.AbstractApplicationContext prepareRefresh
INFO: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@5b37e0d2: startup date [Mon Aug 13 09:46:49 IST 2018]; root of context hierarchy
Aug 13, 2018 9:46:49 AM org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions
INFO: Loading XML bean definitions from class path resource [applicationContext.xml]
setResourceLoader(ResourceLoader resourceLoader) is called by the Spring Container
resourceLoaderAwareImpl = com.ram.aware.ResourceLoaderAwareImpl@5c7fa833
Names from the files are..
Peter
Ram
Juli
Aug 13, 2018 9:46:50 AM org.springframework.context.support.AbstractApplicationContext doClose
INFO: Closing org.springframework.context.support.ClassPathXmlApplicationContext@5b37e0d2: startup date [Mon Aug 13 09:46:49 IST 2018]; root of context hierarchy

Click the below link to download the code:
https://sites.google.com/site/ramj2eev2/java_basics/SpringDemo_ResourceLoaderAware.zip?attredirects=0&d=1

Github Link:
https://github.com/ramram43210/javaee/tree/master/Spring_2018/SpringDemo_ResourceLoaderAware

Bitbucket Link:
https://bitbucket.org/ramram43210/spring/src/d89cccdb22c06b2e0a9adbdbd2c6a120a0f41423/Spring_2018/SpringDemo_ResourceLoaderAware/?at=master

See also:

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Spring MessageSourceAware Java Bean Example | Spring Tutorial | Spring Framework

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Overview: MessageSourceAware in Spring

Internationalization (i18n) and localization (l10n) are essential features for enterprise applications that serve multi-language audiences. In the Spring Framework, message resolution is handled via the MessageSource interface. To allow a Spring bean to resolve internationalized messages directly without tight coupling to the entire container context, Spring provides the MessageSourceAware callback interface.

In this guide, you will learn how the MessageSourceAware interface works, how Spring injects the MessageSource bean during initialization, and how to resolve parameterized, localized messages cleanly.

Understanding MessageSourceAware

The MessageSourceAware interface is a member of Spring's Aware interfaces family designed specifically for message management:

• Lifecycle Injection: When a bean implements MessageSourceAware, Spring calls its setMessageSource(MessageSource messageSource) method after property population and before initialization callbacks.
• Targeted Scope: It provides access strictly to message resolution capabilities, keeping beans focused on their responsibilities without needing a complete ApplicationContext reference.
• Support for Localization: Works seamlessly with ResourceBundleMessageSource or ReloadableResourceBundleMessageSource to look up locale-specific text using keys and parameters.

Step-by-Step Implementation

1. Implement the Interface: Have your bean implement org.springframework.context.MessageSourceAware.
2. Override setMessageSource(): Save the injected MessageSource instance in a field:
   public void setMessageSource(MessageSource messageSource) {
  this.messageSource = messageSource;
}
3. Resolve Messages: Use the getMessage() method to retrieve locale-specific messages by passing the message key, arguments, and target Locale.

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---

Click here to watch on Youtube:
https://www.youtube.com/watch?v=mcVXvOHp3uQ&list=UUhwKlOVR041tngjerWxVccw

Click the below Image to Enlarge:

Spring MessageSourceAware Java Bean Example | Spring Tutorial | Spring Framework

Spring MessageSourceAware Java Bean Example | Spring Tutorial | Spring Framework

Spring MessageSourceAware Java Bean Example | Spring Tutorial | Spring Framework

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%20http://maven.apache.org/maven-v4_0_0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <groupId>com.ram.core</groupId>
    <artifactId>SpringDemo</artifactId>
    <packaging>jar</packaging>
    <version>1.0-SNAPSHOT</version>
    <name>SpringDemo</name>
    <url>http://maven.apache.org</url>

    <properties>
        <spring.version>5.0.2.RELEASE</spring.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>3.8.1</version>
            <scope>test</scope>
        </dependency>

        <!-- Spring 5 dependencies -->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-core</artifactId>
            <version>${spring.version}</version>
        </dependency>

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

messages_en_US.properties

greeting=hello

messages_fr.properties

greeting=Bonjour

MessageSourceAwareImpl.java

package com.ram.aware;

import java.util.Locale;

import org.springframework.context.MessageSource;
import org.springframework.context.MessageSourceAware;

public class MessageSourceAwareImpl implements MessageSourceAware
{

    private MessageSource messageSource;

    public void setMessageSource(MessageSource messageSource)
    {
        System.out.println(
                "setMessageSource(MessageSource messageSource) is called "
                        + "by the Spring Container");
        this.messageSource = messageSource;

    }

    public void displayMessagesSpecificToLocale()
    {

        String englishGreet = messageSource.getMessage("greeting", null,
                Locale.US);
        System.out.println("Greeting in English = " + englishGreet);

        String frenchGreet = messageSource.getMessage("greeting", null,
                Locale.FRENCH);
        System.out.println("Greeting in French  = " + frenchGreet);
    }

}

applicationContext.xml

<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans-4.3.xsd">

    <bean id="messageSourceAware" class="com.ram.aware.MessageSourceAwareImpl" />

    <bean id="messageSource"
        class="org.springframework.context.support.ReloadableResourceBundleMessageSource">
        <property name="basename" value="classpath:messages" />
        <property name="defaultEncoding" value="UTF-8" />
    </bean>

</beans>

App.java

package com.ram.core;

import org.springframework.context.support.ClassPathXmlApplicationContext;

import com.ram.aware.MessageSourceAwareImpl;

public class App
{
    public static void main(String[] args)
    {
        ClassPathXmlApplicationContext applicationContext = new ClassPathXmlApplicationContext(
                "applicationContext.xml");

        MessageSourceAwareImpl messageSourceAwareImpl = applicationContext
                .getBean("messageSourceAware", MessageSourceAwareImpl.class);

        System.out.println("messageSourceAwareImpl = "+messageSourceAwareImpl);

        messageSourceAwareImpl.displayMessagesSpecificToLocale();

        applicationContext.close();
    }
}

Output

Aug 12, 2018 1:26:05 PM org.springframework.context.support.AbstractApplicationContext prepareRefresh
INFO: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@5b37e0d2: startup date [Sun Aug 12 13:26:05 IST 2018]; root of context hierarchy
Aug 12, 2018 1:26:05 PM org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions
INFO: Loading XML bean definitions from class path resource [applicationContext.xml]
setMessageSource(MessageSource messageSource) is called by the Spring Container
messageSourceAwareImpl = com.ram.aware.MessageSourceAwareImpl@1ce92674
Greeting in English = hello
Greeting in French  = Bonjour
Aug 12, 2018 1:26:06 PM org.springframework.context.support.AbstractApplicationContext doClose
INFO: Closing org.springframework.context.support.ClassPathXmlApplicationContext@5b37e0d2: startup date [Sun Aug 12 13:26:05 IST 2018]; root of context hierarchy

Click the below link to download the code:
https://sites.google.com/site/ramj2eev2/java_basics/SpringDemo_MessageSourceAware.zip?attredirects=0&d=1

Github Link:
https://github.com/ramram43210/javaee/tree/master/Spring_2018/SpringDemo_MessageSourceAware

Bitbucket Link:
https://bitbucket.org/ramram43210/spring/src/7263e510faff84cccb3b86c655f02a10c351ddcb/Spring_2018/SpringDemo_MessageSourceAware/?at=master

See also:

All JavaEE Videos Playlist

All JavaEE Videos

All JAVA EE Links

Spring Tutorial

Servlets Tutorial

All Design Patterns Links

JDBC Tutorial

Java Collection Framework Tutorial

JAVA Tutorial

Kids Tutorial

Cooking Tutorial