Spring Boot - Difference Between @Service Annotation and @Repository Annotation

Last Updated : 02 May, 2022

Spring Annotations are a form of metadata that provides data about a program. Annotations are used to provide supplemental information about a program. It does not have a direct effect on the operation of the code they annotate. It does not change the action of the compiled program.

@Service Annotation

In an application, the business logic resides within the service layer so we use the @Service Annotation to indicate that a class belongs to that layer. It is also a specialization of @Component Annotation like the @Repository Annotation. One most important thing about the @Service Annotation is it can be applied only to classes. It is used to mark the class as a service provider. So overall @Service annotation is used with classes that provide some business functionalities. Spring context will autodetect these classes when annotation-based configuration and classpath scanning is used.

Step By Step Implementation

Step 1: Create a Simple Spring Boot Project

Step 2: Add the spring-context dependency in your pom.xml file. Go to the pom.xml file inside your project and add the following spring-context dependency.

XML

<dependency>     <groupId>org.springframework</groupId>     <artifactId>spring-context</artifactId>     <version>5.3.13</version> </dependency>

Step 3: In your project create one package and name the package as "service". In the service, the package creates a class and name it as "MyServiceClass".

Java

// Java Program to Illustrate MyServiceClass  // Importing package module to code module package com.example.demo.service; // Importing required classes import org.springframework.stereotype.Service;  // Annotation @Service  // Class public class MyServiceClass {      // Method     // To compute factorial     public int factorial(int n)     {         // Base case         if (n == 0)             return 1;          return n * factorial(n - 1);     } }

In this code notice that it’s a simple java class that provides functionalities to calculate the factorial of a number. So we can call it a service provider. We have annotated it with @Service annotation so that spring-context can autodetect it and we can get its instance from the context.

Step 4: Spring Repository Test

So now our Spring Repository is ready, let’s test it out. Go to the DemoApplication.java file and refer to the below code.

Java

// Java Program to Illustrate DemoApplication  // Importing package module to code fragment package com.example.demo; // Importing required classes import com.example.demo.service.MyServiceClass; import org.springframework.boot.autoconfigure.SpringBootApplication; import org.springframework.context.annotation.AnnotationConfigApplicationContext;  // Annotation @SpringBootApplication  // Main class public class DemoApplication {      // MAin driver method     public static void main(String[] args)     {          AnnotationConfigApplicationContext context             = new AnnotationConfigApplicationContext();         context.scan("com.example.demo");          context.refresh();          MyServiceClass myServiceClass             = context.getBean(MyServiceClass.class);          // Testing the factorial method         int factorialOf5 = myServiceClass.factorial(5);         System.out.println("Factorial of 5 is: "                            + factorialOf5);          // Closing the spring context         // using close() method         context.close();     } }

Output:

@Repository Annotation

@Repository Annotation is a specialization of @Component annotation which is used to indicate that the class provides the mechanism for storage, retrieval, update, delete and search operation on objects. Though it is a specialization of @Component annotation, so Spring Repository classes are autodetected by spring framework through classpath scanning. This annotation is a general-purpose stereotype annotation which very close to the DAO pattern where DAO classes are responsible for providing CRUD operations on database tables.

Step By Step Implementation

Step 1: Create a Simple Spring Boot Project

Refer to this article Create and Setup Spring Boot Project in Eclipse IDE and create a simple spring boot project.

Step 2: Add the spring-context dependency in your pom.xml file. Go to the pom.xml file inside your project and add the following spring-context dependency.

XML

<dependency>     <groupId>org.springframework</groupId>     <artifactId>spring-context</artifactId>     <version>5.3.13</version> </dependency>

Step 3: In your project create two packages and name the package as "entity" and "repository". In the entity, package creates a class name it as Student. In the repository, the package creates a Generic Interface named as DemoRepository and a class name it as StudentRepository.

Step 4: Create an entity class for which we will implement a spring repository. Here our entity class is Student. Below is the code for the Student.java file.

Java

// Java Program to Illustrate Simple POJO (Plain Old Java // Object) Class  package com.example.demo.entity;  // Class public class Student {      // Attributes     private Long id;     private String name;     private int age;      // Generating the constructor     public Student(Long id, String name, int age)     {         this.id = id;         this.name = name;         this.age = age;     }      // Getter-setters     public Long getId() { return id; }      public void setId(Long id) { this.id = id; }      public String getName() { return name; }      public void setName(String name) { this.name = name; }      public int getAge() { return age; }      public void setAge(int age) { this.age = age; }      // Overriding toString() method of String class     @Override public String toString()     {         return "Student{"             + "id=" + id + ", name='" + name + '\''             + ", age=" + age + '}';     } }

Step 5: Before implementing the Repository class we have created a generic DemoRepository interface to provide the contract for our repository class to implement.

Java

// Java Program to illustrate DemoRepository File  package com.example.demo.repository;  public interface DemoRepository<T> {      // Save method     public void save(T t);      // Find a student by its id     public T findStudentById(Long id);  }

Step 6: Now let’s look at our StudentRepository class implementation.

Java

// Java Program to Illustrate StudentRepository File  package com.example.demo.repository;  import com.example.demo.entity.Student; import org.springframework.stereotype.Repository;  import java.util.HashMap; import java.util.Map;  @Repository public class StudentRepository implements DemoRepository<Student> {      // Using an in-memory Map     // to store the object data     private Map<Long, Student> repository;      public StudentRepository() {         this.repository = new HashMap<>();     }      // Implementation for save method     @Override     public void save(Student student) {         repository.put(student.getId(), student);     }      // Implementation for findStudentById method     @Override     public Student findStudentById(Long id) {         return repository.get(id);     } }

In this StudentRepository.java file, you can notice that we have added the @Repository annotation to indicate that the class provides the mechanism for storage, retrieval, update, delete and search operation on objects.

Note: Here we have used an in-memory Map to store the object data, you can use any other mechanisms too. In the real world, we use Databases to store object data.

Step 7: Spring Repository Test

So now our Spring Repository is ready, let’s test it out. Go to the DemoApplication.java file and refer to the below code.

Java

// Java Program to Illustrate Spring Repository Test  package com.example.demo;  import com.example.demo.entity.Student; import com.example.demo.repository.StudentRepository; import org.springframework.boot.autoconfigure.SpringBootApplication; import org.springframework.context.annotation.AnnotationConfigApplicationContext;  // Class @SpringBootApplication public class DemoApplication {      // Main driver method     public static void main(String[] args)     {          AnnotationConfigApplicationContext context             = new AnnotationConfigApplicationContext();         context.scan("com.example.demo");         context.refresh();          StudentRepository repository             = context.getBean(StudentRepository.class);          // Testing the store method         repository.save(new Student(1L, "Anshul", 25));         repository.save(new Student(2L, "Mayank", 23));          // Testing the retrieve method         Student student = repository.findStudentById(1L);         System.out.println(student);          // Closing the spring context         // using standard close() method         context.close();     } }

Output: Lastly, run your application and you should get the following output as shown below as follows:

Difference Between @Service Annotation and @Repository Annotation

@Service Annotation	@Repository Annotation
@Service annotation is used with classes that provide some business functionalities.	@Repository Annotation is used to indicate that the class provides the mechanism for storage, retrieval, update, delete and search operation on objects.
@Service Annotation is a specialization of @Component Annotation.	@Repository Annotation is also a specialization of @Component Annotation.
It can be applied only to classes.	It is used at the class level.
It is used to mark the class as a service provider.	It is used to mark the interface as DAO (Data Access Object) provider.
It is a Stereotype Annotations.	It is also a Stereotype Annotations.

Spring Boot - Difference Between @Service Annotation and @Repository Annotation

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Spring Boot - Difference Between @Service Annotation and @Repository Annotation

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@Repository Annotation

Difference Between @Service Annotation and @Repository Annotation

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