JAVA EE: Aggregating @Configuration classes with @Import

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Aggregating @Configuration classes with @Import | 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 http://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>SpringHelloWorld</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>

Employee.java

package com.ram.core;

/**
 * Spring bean
 *
 */

public class Employee

{

    private String name;

    public Employee(String name)

    {

        System.out.println(this.getClass().getName()

                + ", Employee(String name) constructor is called, " + name);

        this.name = name;

    }

    public void employeeDetails()

    {

        System.out.println("Employee Name =  " + name);

    }

}

Customer.java

package com.ram.core;

/**
 * Spring bean
 *
 */

public class Customer

{

    private String name;

    public Customer(String name)

    {

        System.out.println(this.getClass().getName()

                + ", Customer(String name) constructor is called, " + name);

        this.name = name;

    }

    public void customerDetails()

    {

        System.out.println("Customer Name =  " + name);

    }

}

EmployeeConfig.java

package com.ram.config;

import org.springframework.context.annotation.Bean;

import org.springframework.context.annotation.Configuration;

import com.ram.core.Employee;

@Configuration

public class EmployeeConfig

{

    @Bean(name = "employee")

    public Employee employee()

    {

        System.out.println(

                "In EmployeeConfig employee() is called by the Spring container");

        return new Employee("Peter");

    }

}

CustomerConfig.java

package com.ram.config;

import org.springframework.context.annotation.Bean;

import org.springframework.context.annotation.Configuration;

import com.ram.core.Customer;

@Configuration

public class CustomerConfig

{

    @Bean(name = "customer")

    public Customer customer()

    {

        System.out.println(

                "In CustomerConfig employee() is called by the Spring container");

        return new Customer("John");

    }

}

AppConfig.java

package com.ram.config;

import org.springframework.context.annotation.Configuration;

import org.springframework.context.annotation.Import;

@Configuration

@Import({ EmployeeConfig.class, CustomerConfig.class })

public class AppConfig

{

}

App.java

package com.ram.core;

import org.springframework.context.ApplicationContext;

import org.springframework.context.annotation.AnnotationConfigApplicationContext;

import com.ram.config.AppConfig;

public class App

{

    public static void main(String[] args)

    {

        ApplicationContext context = new AnnotationConfigApplicationContext(

                AppConfig.class);

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

        Employee employee = (Employee) context.getBean("employee");

        System.out.println("Got employee object from the ApplicationContext");

        employee.employeeDetails();

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

        Customer customer = (Customer) context.getBean("customer");

        System.out.println("Got customer object from the ApplicationContext");

        customer.customerDetails();

    }

}

Output

Oct 07, 2018 7:32:15 AM org.springframework.context.support.AbstractApplicationContext prepareRefresh

INFO: Refreshing org.springframework.context.annotation.AnnotationConfigApplicationContext@5f4da5c3: startup date [Sun Oct 07 07:32:15 IST 2018]; root of context hierarchy

In EmployeeConfig employee() is called by the Spring container

com.ram.core.Employee, Employee(String name) constructor is called, Peter

In CustomerConfig employee() is called by the Spring container

com.ram.core.Customer, Customer(String name) constructor is called, John

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

Got employee object from the ApplicationContext

Employee Name =  Peter

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

Got customer object from the ApplicationContext

Customer Name =  John