JAVA EE: How to define custom component name in Spring Auto Scanning Components

Thursday, 30 August 2018

How to define custom component name in Spring Auto Scanning Components | Spring Tutorial

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Overview: Naming Spring Beans in Auto Scanning

When using auto component scanning in the Spring Framework, Spring automatically registers discovered classes into the ApplicationContext. By default, it assigns a bean name using decapitalized camel-case naming (for example, CustomerService becomes customerService). However, situations often arise where you want to specify an explicit, custom bean identifier to make bean retrieval or qualifier matching clearer and more predictable.

In this guide, you will learn how to assign custom component names using stereotype annotations during automatic component scanning in Spring.

Default Naming vs. Custom Component Names

Understanding how Spring names scanned beans helps you organize your architecture and avoid bean identifier collisions:

Default Bean Naming Strategy: Spring relies on BeanNameGenerator (typically AnnotationBeanNameGenerator), which takes the short class name and lowers the first character.
Custom Bean Naming via Annotations: You can override the default naming convention by passing a string value directly into @Component("myCustomName") or related stereotypes (@Service, @Repository, @Controller).
Predictable Injection: Custom names allow seamless integration with @Qualifier("myCustomName") or @Resource(name = "myCustomName") when resolving bean ambiguities.

Step-by-Step Implementation

Add Stereotype with Custom Value: Define the custom bean name directly in the annotation parameter:
@Component("customOrderManager") public class OrderManager { ... }
Retrieve or Inject the Bean: You can retrieve the bean directly by its custom name from the container:
OrderManager orderManager = (OrderManager) context.getBean("customOrderManager");
Inject via Qualifiers: Alternatively, reference it cleanly with @Qualifier("customOrderManager") inside collaborating classes.

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How to define custom component name in Spring Auto Scanning Components | Spring Tutorial

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>

EmployeeDAO.java

package com.ram.dao;

import org.springframework.stereotype.Component;

@Component

public class EmployeeDAO

{

    public void addEmployee()

    {

        System.out.println("inside EmployeeDAO addEmployee()");

    }

}

EmployeeService.java

package com.ram.service;

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

import org.springframework.stereotype.Component;

import com.ram.dao.EmployeeDAO;

@Component("empSer")

public class EmployeeService

{

    @Autowired

    EmployeeDAO employeeDAO;

    public void addEmployee()

    {

        System.out.println("inside EmployeeService addEmployee()");

        employeeDAO.addEmployee();

    }

    @Override

    public String toString()

    {

        return "EmployeeService [employeeDAO=" + employeeDAO + "]";

    }

}

applicationContext.xml

<beans xmlns="http://www.springframework.org/schema/beans"

    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-4.3.xsd

    http://www.springframework.org/schema/context

    http://www.springframework.org/schema/context/spring-context-4.3.xsd">

    <context:component-scan base-package="com.ram" />

</beans>

App.java

package com.ram.core;

import org.springframework.context.ApplicationContext;

import org.springframework.context.support.ClassPathXmlApplicationContext;

import com.ram.service.EmployeeService;

public class App

{

    public static void main(String[] args)

    {

        ApplicationContext context = new ClassPathXmlApplicationContext(

                "applicationContext.xml");

        System.out.println("---------------------------------------");

        EmployeeService employeeService = context.getBean("empSer",

                EmployeeService.class);

        System.out.println(

                "Got employeeService object from the ApplicationContext(Spring Container)");

        System.out.println(employeeService);

        employeeService.addEmployee();

    }

}

Output

Aug 15, 2018 9:59:15 AM org.springframework.context.support.AbstractApplicationContext prepareRefresh

INFO: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@5b37e0d2: startup date [Wed Aug 15 09:59:15 IST 2018]; root of context hierarchy

Aug 15, 2018 9:59:15 AM org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions

INFO: Loading XML bean definitions from class path resource [applicationContext.xml]

---------------------------------------

Got employeeService object from the ApplicationContext(Spring Container)

EmployeeService [employeeDAO=com.ram.dao.EmployeeDAO@16022d9d]

inside EmployeeService addEmployee()

inside EmployeeDAO addEmployee()