Beans and Dependency Injection

In Spring Boot, we can use Spring Framework to define our beans and their dependency injection. The @ComponentScan annotation is used to find beans and the corresponding injected with @Autowired annotation.

If you followed the Spring Boot typical layout, no need to specify any arguments for @ComponentScan annotation. All component class files are automatically registered with Spring Beans.

The following example provides an idea about Auto wiring the Rest Template object and creating a Bean for the same −

@Bean
public RestTemplate getRestTemplate() {
   return new RestTemplate();
}

The following code shows the code for auto wired Rest Template object and Bean creation object in main Spring Boot Application class file −

package com.maixuanviet.demo;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.Bean;
import org.springframework.web.client.RestTemplate;

@SpringBootApplication
public class DemoApplication {
@Autowired
   RestTemplate restTemplate;
   
   public static void main(String[] args) {
      SpringApplication.run(DemoApplication.class, args);
   }
   @Bean
   public RestTemplate getRestTemplate() {
      return new RestTemplate();   
   }
}