"Welcome To Ashok IT"				
			                      "Spring Boot and MicroServices"
                                               Topic : Autowiring Using Annotations
                                               Date  : 19/03/2024
                                                (Session - 07)                               
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Autowiring through Annotation
=============================
* Autowiring  >> Reducing the XML Configuration in Spring Application

                 Injecting the dependencies implictly with out any XML configuration

                 It can be applicable only for "Dependency in the form of objects" properties

                 Autowiring strategies are no,byName,byType,Constructor

                 We can achieve autowiring concept using xml Approach and Annotation Approach

                 We already completed xml approach now we are going to explore on Annotation Approach

* If we need to work with Autowiring using Annotations the spring provided @Autowired annotation

     @Autowired Annotation >> Field level, Setter method, Constructor

* Most in the project development we are always prefer to use @Autowired annotation on top of Fields only.

* If we add the @Autowired Annotation on top of Field means it will apply either byName/byType Strategy.

     byName/byType strategy container will use Setter Injection internally.

      Case-1
      =======
         @Autowired          
         private User user; // Field

         Spring.xml
         ===========
         <bean id="user" class="com.ashokit.beans.User"/>

       Observation :: Property Name and bean definition id value is matched then container will apply byName strategy

      Case-2
      ======
         @Autowired          
         private User userObj; // Field

         Spring.xml
         ===========
         <bean id="user" class="com.ashokit.beans.User"/>

       Observation :: Property Name and bean definition id value is not matched then container will apply byType                                    strategy


    Activating the IOC Container to Read and execute @Autowired Annotation
    ======================================================================= 
        <context:annotation-config/>

Demo.java
=========
package com.ashokit.spring.beans;

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

public class Demo {
	
	@Autowired
	@Qualifier(value = "currentUser1")  // Qualifying the particular bean definition out of multiple bean definitions
	private User user;
	
	public void displayData() {
		String userDetails = user.getUserDetails();
		System.out.println(userDetails);
	}

}


User.java
=========
package com.ashokit.spring.beans;

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

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

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

SpringClient.java
=================
package com.ashokit.spring.client;

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

import com.ashokit.spring.beans.Demo;

public class SpringClient {
	
	public static void main(String[] args) {
		
		ApplicationContext context = new ClassPathXmlApplicationContext("spring.xml");
		
		Demo demo = (Demo)context.getBean("demo");
		demo.displayData();
		
	}

}

Spring.xml
==========
<?xml version="1.0" encoding="UTF-8"?>
<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
		https://www.springframework.org/schema/beans/spring-beans.xsd
		http://www.springframework.org/schema/context
		https://www.springframework.org/schema/context/spring-context.xsd">

     	<!-- configuring the Demo class -->
     <bean id="demo" class="com.ashokit.spring.beans.Demo"/>
     
          <!--configuring the User class -->
     <bean id="currentUser" class="com.ashokit.spring.beans.User">
        <property name="username" value="Mahesh.ashokit"/>
        <property name="password" value="Test@123"/>
     </bean>
     
         <!--configuring the User class -->
     <bean id="currentUser1" class="com.ashokit.spring.beans.User">
        <property name="username" value="ashok.ashokit"/>
        <property name="password" value="Ashokit@123"/>
     </bean>
     
       <!--configuring the User class -->
     <bean id="user" class="com.ashokit.spring.beans.User">
        <property name="username" value="rajesh.ashokit"/>
        <property name="password" value="Rajesh@123"/>
     </bean>
     
     <!--  Read and execute spring provided annotations -->
     <context:annotation-config/>
       
</beans>
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