Bean Configuration - bhudevi0924/Spring-boot GitHub Wiki

Annotation based configuration: (Implicit Bean Discovery)

• Different annotations used in application are @Controller, @Service, @Repository, @Controller. These annotations are used to defining various layers of files. Based on these annotation, the files are configured as managed by spring beans and the spring will automatically create a bean.

• @Autowired annotation can be used for injecting dependencies automatically.

    package com.example.demo.services;
  
    import org.springframework.stereotype.Service;
  
    @Service
    public class Service_Name {
        public void metho_name() {
            System.out.println("Creates bean.");
        }
    }
  

Java Configuration: (Programmatic configuration of beans)

• Define a bean using "@Bean" annotation within a Java configuration class annotated with "@Configuration".

   package com.example.demo.config;
  
   import org.springframework.context.annotation.Bean;
   import org.springframework.context.annotation.Configuration;
   import com.example.demo.services.MyService;
  
   @Configuration
   public class AppConfig {
  
       @Bean
       public MyService myService() {
           return new MyService();
       }
   }
  

XML Configuration:

• Uses Xml configuration files (eg: applicationContext.xml) to define beans and their dependencies.

   <?xml version="1.0" encoding="UTF-8"?>
   <beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
       http://www.springframework.org/schema/beans/spring-beans.xsd">
  
       <!-- Define a bean for MyService -->
       <bean id="myService" class="com.example.demo.services.MyService"/>
  
   </beans>