Table of Contents

URL: https://www.progressiverobot.com/spring-repository-annotation/

Spring @Repository annotation is used to indicate that the class provides the mechanism for storage, retrieval, search, update and delete operation on objects.

Spring @Repository Annotation

spring repository illustration for: Spring @Repository Annotation

Spring Repository annotation is a specialization of [@Component](/community/tutorials/spring-component) annotation, so Spring Repository classes are autodetected by [spring framework](/community/tutorials/spring-framework) through classpath scanning. Spring Repository is very close to [DAO](/community/tutorials/dao-design-pattern) pattern where DAO classes are responsible for providing CRUD operations on database tables. However, if you are using [Spring Data](/community/tutorials/spring-data-jpa) for managing database operations, then you should use Spring Data Repository interface.

Spring Repository Example

Let's look at a simple example where we will create a Spring Repository class. We will not use database operations, rather we will provide a repository for an Object. Create a maven project in Eclipse or any other IDE you use, then add spring core dependency.

				
					<dependency>
	<groupId>org.springframework</groupId>
	<artifactId>spring-context</artifactId>
	<version>5.0.6.RELEASE</version>
</dependency>

Below image shows our final project structure in Eclipse. !Spring Repository Example Let's create the model class for which we will implement a spring repository.

				
					package com.journaldev.spring.model;

public class Employee {

	private int id;
	private String name;
	private String jobTitle;

	public Employee() {
	}

	public Employee(int i, String n, String jt) {
		this.id = i;
		this.name = n;
		this.jobTitle = jt;
	}

	public int getId() {
		return id;
	}

	public void setId(int id) {
		this.id = id;
	}

	public String getName() {
		return name;
	}

	public void setName(String name) {
		this.name = name;
	}

	public String getJobTitle() {
		return jobTitle;
	}

	public void setJobTitle(String jobTitle) {
		this.jobTitle = jobTitle;
	}

	@Override
	public String toString() {
		return id + "," + name + "," + jobTitle;
	}
}

Before we implement Repository class, I have created a generic ObjectRepository interface to provide the contract for our repository class to implement.

				
					package com.journaldev.spring.repository;

public interface ObjectRepository<T> {

	public void store(T t);

	public T retrieve(int id);

	public T search(String name);

	public T delete(int id);
}

I am using Generics here, it's a powerful technology to provide loosely coupled contract for the applications to implement. Now let's look at our Repository class implementation.

				
					package com.journaldev.spring.repository;

import java.util.Collection;
import java.util.HashMap;
import java.util.Map;

import org.springframework.stereotype.Repository;

import com.journaldev.spring.model.Employee;

@Repository
public class EmployeeRepository implements ObjectRepository<Employee> {

	private Map<Integer, Employee> repository;

	public EmployeeRepository() {
		this.repository = new HashMap<>();
	}

	@Override
	public void store(Employee emp) {
		repository.put(emp.getId(), emp);
	}

	@Override
	public Employee retrieve(int id) {
		return repository.get(id);
	}

	@Override
	public Employee search(String name) {
		Collection<Employee> emps = repository.values();
		for (Employee emp : emps) {
			if (emp.getName().equalsIgnoreCase(name))
				return emp;
		}
		return null;
	}

	@Override
	public Employee delete(int id) {
		Employee e = repository.get(id);
		this.repository.remove(id);
		return e;
	}

}

Note that I am using an in-memory [Map](/community/tutorials/java-map) to store the object data, you can use any other mechanisms too.

Spring Repository Test

Our Spring Repository is ready, let's create a main class and test it out.

				
					package com.journaldev.spring;

import java.sql.SQLException;

import org.springframework.context.annotation.AnnotationConfigApplicationContext;

import com.journaldev.spring.model.Employee;
import com.journaldev.spring.repository.EmployeeRepository;

public class SpringMainClass {

	public static void main(String[] args) throws SQLException {
		AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext();
		context.scan("com.journaldev.spring");
		context.refresh();

		EmployeeRepository repository = context.getBean(EmployeeRepository.class);

		// store
		repository.store(new Employee(1, "Pankaj", "CEO"));
		repository.store(new Employee(2, "Anupam", "Editor"));
		repository.store(new Employee(3, "Meghna", "CFO"));

		// retrieve
		Employee emp = repository.retrieve(1);
		System.out.println(emp);

		// search
		Employee cfo = repository.search("Meghna");
		System.out.println(cfo);

		// delete
		Employee editor = repository.delete(2);
		System.out.println(editor);

		// close the spring context
		context.close();
	}

}

Just run the class as Java Application and you should get following output.

				
					1,Pankaj,CEO
3,Meghna,CFO
2,Anupam,Editor

You can download the example code from our GitHub Repository.

Reference: API Doc