JAVA EE: Spring bean java based configuration using @Configuration and @Bean[employee constructor]

Monday 29 October 2018

Spring bean java based configuration using @Configuration and @Bean[employee constructor]

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Spring bean java based configuration using @Configuration and @Bean[employee constructor]

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>

Employee.java

package com.ram.model;

public class Employee

{

    private int id;

    private String name;

    public Employee(int id, String name)

    {

        System.out.println("Employee(int id, String name) constructor "

                + "is called by the Spring container");

        this.id = id;

        this.name = name;

    }

    public void displayEmployeeDetails()

    {

        System.out.println("Employee [id=" + id + ", name=" + name + "]");

    }

}

ApplicationBeans.java

package com.ram.config;

import org.springframework.context.annotation.Bean;

import org.springframework.context.annotation.Configuration;

import com.ram.model.Employee;

/**

 * Annotate with @Configuration to tell Spring that this is the core

 * Spring configuration file, and define bean via @Bean.

 */

@Configuration

public class ApplicationBeans

{

    @Bean(name = "employee")

    public Employee getEmployee()

    {

        return new Employee(36,"Peter");

    }

}

App.java

package com.ram.core;

import org.springframework.context.ApplicationContext;

import org.springframework.context.annotation.AnnotationConfigApplicationContext;

import com.ram.config.ApplicationBeans;

import com.ram.model.Employee;

public class App

{

    public static void main(String[] args)

    {

        ApplicationContext context = new AnnotationConfigApplicationContext(

                ApplicationBeans.class);

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

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

        System.out.println(

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

        employee.displayEmployeeDetails();

    }

}

Output

Sep 30, 2018 10:47:21 AM org.springframework.context.support.AbstractApplicationContext prepareRefresh

INFO: Refreshing org.springframework.context.annotation.AnnotationConfigApplicationContext@5f4da5c3: startup date [Sun Sep 30 10:47:21 IST 2018]; root of context hierarchy

Employee(int id, String name) constructor is called by the Spring container

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

Got employee object from the ApplicationContext(Spring Container)

Employee [id=36, name=Peter]