"Welcome To Ashok IT"				
			                       "Spring Boot and MicroServices"
                                                Topic : JavaBasedConfiguration
                                                Date  : 31/08/2024
                                                  (Session - 14)                               
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Last Session
=============
* We discussed about ApplicationContext Container

Today Session
==============   
Java Based Configuration Development
=====================================
* In addition to XML-based configuration, Spring also supports Java-based configuration and its new style of developing         Spring Application.

* It allows you to configure your Spring beans and dependencies using Java code. 

* Java-based configuration provides a more programmatic and type-safe approach compared to XML configuration. 

Steps for Developing Java Based Configuration Application
=========================================================

1) Enable Java-based configuration: 
===================================
* To enable Java-based configuration in your Spring application, you need to add the @Configuration annotation to a class.    

* This class will serve as your configuration class similarly to xml configuration file.

Example
=======
@Configuration
public class AppConfig {
    // Bean definitions and configuration methods
}

2) Define beans: 
================
* In your configuration class, you can define beans using the @Bean annotation on methods. The return type of the method        represents the type of the bean, and the method body contains the logic to create and configure the bean.

Example
=======
@Configuration
public class AppConfig {
    
    @Bean
    public MyBean myBean() {
        return new MyBean();
    }
    
    @Bean
    public AnotherBean anotherBean() {
        return new AnotherBean();
    }
}

3) Main Program
===============
 * We can create the Main Program by Creating object of ApplicationContext with its implementation Class                AnnotationConfigApplicationContext.

 * AnnotationConfigApplicationContext implementation class having capability to read the configurations from Java based       configuration class.

 * We need to provide the Configuration class to AnnotationConfigApplicationContext class.

Example
======
  public class MainClient{

     public static void main(String[] args){
        
           ApplicationContext context = new AnnotationConfigApplicationContext(AppConfig.class);

           //Requesting the Spring bean logic
     }

  }

Example Application on Java Based Configuration
===============================================
User.java
=========
package com.ashokit.beans;

public class User {
	
	private String username;
	
	private String password;

	//setter injection
	public void setUsername(String username) {
		this.username = username;
	}

	public void setPassword(String password) {
		this.password = password;
	}
	
	@Override
	public String toString() {
		return String.format("Username %s and password %s",username,password);
	}
}

Student.java
============
package com.ashokit.beans;

public class Student {
	
	//simple properties
	private String id;
	
	private String name;
	
	private String emailId;
	
	//Object
	private Course course;
	
	//setter injection
	public void setId(String id) {
		this.id = id;
	}
	
	public void setName(String name) {
		this.name = name;
	}
	
	public void setEmailId(String emailId) {
		this.emailId = emailId;
	}
	
	public void setCourse(Course course) {
		this.course = course;
	}
	
	@Override
	public String toString() {
		return String.format("StudentId %s and StudentName %s and EmailId %s and CourseName %s",id,name,emailId,course.getCourseName());
	}

}

Course.java
===========
package com.ashokit.beans;

public class Course {
	
	private String courseName;
	
	private Integer courseFee;	
	
	public void setCourseName(String courseName) {
		this.courseName = courseName;
	}
	
	public void setCourseFee(Integer courseFee) {
		this.courseFee = courseFee;
	}
	
	public String getCourseName() {
		return courseName;
	}
	
	public Integer getCourseFee() {
		return courseFee;
	}
	
	@Override
	public String toString() {
		return String.format("CourseName %s and CourseFee %s ", courseName,courseFee);
	}
}

SpringConfig.java
=================
package com.ashokit.config;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

import com.ashokit.beans.Course;
import com.ashokit.beans.Student;
import com.ashokit.beans.User;

//This will acts as Spring Configuration File
@Configuration
public class SpringConfig {
	
	//creating the Java method to represent as Spring bean i.e.,User
	@Bean
	public User getUserObject() {
		
		//return new User();
		User user = new User();
		user.setUsername("Mahesh");
		user.setPassword("Mahesh@123");
		return user;
	}
	
	//creating the Java method to represent as Spring bean i.e.,Address
	@Bean
	public Student getStudentObject() {
		Student st = new Student();
		st.setId("AIT123");
		st.setName("Mahesh");
		st.setEmailId("mahesh.ashokit@gmail.com");
		//Injecting the courseBean into student Bean
		st.setCourse(getCourseBean());
		return st;
	}
	
	@Bean
	public Course getCourseBean() {
		Course course = new Course();
		course.setCourseName("SpringBootMicroservices");
		course.setCourseFee(8000);
		return course;
	}
}


SpringClient.java
=================
import org.springframework.context.ApplicationContext;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;

import com.ashokit.beans.Student;
import com.ashokit.beans.User;
import com.ashokit.config.SpringConfig;

public class SpringClient {
	
	public static void main(String[] args) {
		
		//creating the object for spring container and passing Java Based Configuration class
		ApplicationContext context = new AnnotationConfigApplicationContext(SpringConfig.class);
		
		//Requesting the Spring beans
		User user = context.getBean(User.class);
		System.out.println(user.hashCode());
		User user1 = context.getBean(User.class);
		System.out.println(user1.hashCode());
		
		
		Student student = context.getBean(Student.class);
		System.out.println(student.hashCode());
		Student student1 = context.getBean(Student.class);
		System.out.println(student1.hashCode());
	}
}


OUTPUT
======
Username Mahesh and password Mahesh@123
StudentId AIT123 and StudentName Mahesh and EmailId mahesh.ashokit@gmail.com and CourseName SpringBootMicroservices

Inheriting configuration classes
================================
package com.ashokit.config;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Import;

import com.ashokit.beans.Course;
import com.ashokit.beans.Student;
import com.ashokit.beans.User;

//This will acts as Spring Configuration File
@Configuration
@Import(value = {DatabaseConfig.class,EmailConfig.class}) //Inheriting the configuration from DatabaseConfig class
public class SpringConfig {
	
	//creating the Java method to represent as Spring bean i.e.,User
	@Bean
	public User getUserObject() {
		
		//return new User();
		User user = new User();
		user.setUsername("Mahesh");
		user.setPassword("Mahesh@123");
		return user;
	}
	
	//creating the Java method to represent as Spring bean i.e.,Address
	@Bean
	public Student getStudentObject() {
		Student st = new Student();
		st.setId("AIT123");
		st.setName("Mahesh");
		st.setEmailId("mahesh.ashokit@gmail.com");
		//Injecting the courseBean into student Bean
		st.setCourse(getCourseBean());
		return st;
	}
	
	@Bean
	public Course getCourseBean() {
		Course course = new Course();
		course.setCourseName("SpringBootMicroservices");
		course.setCourseFee(8000);
		return course;
	}
}

NOTE
====
* @Import Annotation is used to import the spring bean definitions from another Spring Configuration classes.

* @ImportResource annotation is used to import the Spring bean definitions from XML file.
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