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Spring @Repository Annotation

@Repository annotation can be called as specialized form of @Component annotation. By annotating a class with @Repository annotation we indicate that a class is a "Data Access Object", may also apply this stereotype to DAO classes or something similar. There is no any other specialty from @Component annotation except using it for the DAO class. A class thus annotated is eligible for Spring DataAccessException translation when used in conjunction with a PersistenceExceptionTranslationPostProcessor. The annotated class is also clarified as to its role in the overall application architecture for the purpose of tooling, aspects, etc.

Let’s create a simple spring application where we use @Service annotation.

Spring @Repository Annotation Example

Database script (MySQL)

CREATE TABLE STUDENT (

       STUDENTID INT NOT NULL AUTO_INCREMENT,

       FIRSTNAME VARCHAR(20) DEFAULT NULL,

       LASTNAME VARCHAR(20) DEFAULT NULL,

       MARKS INT(20) DEFAULT NULL,

       PRIMARY KEY (STUDENTID)

);

pom.xml

<project xmlns="https://maven.apache.org/POM/4.0.0"

        xmlns:xsi="https://www.w3.org/2001/XMLSchema-instance"

        xsi:schemaLocation="https://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">

        <modelVersion>4.0.0</modelVersion>

        <groupId>com.java4coding</groupId>

        <artifactId>SpringDataJPA_Repository_Annotation_Example</artifactId>

        <version>0.0.1-SNAPSHOT</version>

 

        <dependencies>

                <dependency>

                        <groupId>org.springframework</groupId>

                        <artifactId>spring-context</artifactId>

                        <version>5.1.4.RELEASE</version>

                </dependency>

                <dependency>

                        <groupId>org.springframework</groupId>

                        <artifactId>spring-orm</artifactId>

                        <version>5.1.4.RELEASE</version>

                </dependency>

                <dependency>

                        <groupId>org.hibernate</groupId>

                        <artifactId>hibernate-core</artifactId>

                        <version>5.4.1.Final</version>

                </dependency>

                <dependency>

                        <groupId>org.springframework.data</groupId>

                        <artifactId>spring-data-jpa</artifactId>

                        <version>2.1.4.RELEASE</version>

                </dependency>

                <dependency>

                        <groupId>mysql</groupId>

                        <artifactId>mysql-connector-java</artifactId>

                        <version>8.0.14</version>

                </dependency>

        </dependencies>

 

        <build>

                <plugins>

                        <plugin>

                                <groupId>org.apache.maven.plugins</groupId>

                                <artifactId>maven-compiler-plugin</artifactId>

                                <version>3.8.1</version>

                                <configuration>

                                        <source>1.8</source>

                                        <target>1.8</target>

                                </configuration>

                        </plugin>

                </plugins>

        </build>

</project>

persistence.xml

<?xml version="1.0" encoding="UTF-8"?>

<persistence xmlns="https://java.sun.com/xml/ns/persistence"

        xmlns:xsi="https://www.w3.org/2001/XMLSchema-instance"

        xsi:schemaLocation="https://java.sun.com/xml/ns/persistence

             https://java.sun.com/xml/ns/persistence/persistence_2_0.xsd"

        version="2.0">

 

        <persistence-unit name="StudentPU">

                <provider>org.hibernate.ejb.HibernatePersistence</provider>

                <properties>

                        <property name="hibernate.connection.url" value="jdbc:mysql://localhost:3306/study" />

                        <property name="hibernate.connection.driver_class" value="com.mysql.cj.jdbc.Driver" />

                        <property name="hibernate.connection.username" value="root" />

                        <property name="hibernate.connection.password" value="root" />

                        <property name="hibernate.archive.autodetection" value="class" />

                        <property name="hibernate.show_sql" value="true" />

                        <property name="hibernate.format_sql" value="true" />

                        <property name="hbm2ddl.auto" value="update" />

                </properties>

        </persistence-unit>

</persistence>

Student.java

package com.java4coding;

 

import javax.persistence.Entity;

import javax.persistence.GeneratedValue;

import javax.persistence.GenerationType;

import javax.persistence.Id;

import javax.persistence.NamedQueries;

import javax.persistence.NamedQuery;

 

@Entity

public class Student {

 

        @Id

        @GeneratedValue(strategy = GenerationType.IDENTITY)

        private Long studentId;

        private String firstName;

        private String lastName;

        private Long marks;

        public Student() {

                super();

        }

       

        public Student(String firstName, String lastName, Long marks) {

                super();

                this.firstName = firstName;

                this.lastName = lastName;

                this.marks = marks;

        }

       

        //Setters and getters

        public Long getId() {

                return studentId;

        }

 

        public void setId(Long id) {

                this.studentId = id;

        }

 

        public String getFirstName() {

                return firstName;

        }

 

        public void setFirstName(String firstName) {

                this.firstName = firstName;

        }

 

        public String getLastName() {

                return lastName;

        }

 

        public void setLastName(String lastName) {

                this.lastName = lastName;

        }

       

        public Long getMarks() {

                return marks;

        }

 

        public void setMarks(Long marks) {

                this.marks = marks;

        }

 

        @Override

        public String toString() {

                return "Student [firstName=" + firstName + ", lastName=" + lastName + ", Marks= " + marks + "]";

        }

}

 

AppConfig.java

package com.java4coding;

 

import javax.persistence.EntityManagerFactory;

 

import org.springframework.context.annotation.Bean;

import org.springframework.context.annotation.Configuration;

import org.springframework.data.jpa.repository.config.EnableJpaRepositories;

import org.springframework.orm.jpa.JpaTransactionManager;

import org.springframework.orm.jpa.LocalEntityManagerFactoryBean;

 

@Configuration

@EnableJpaRepositories(basePackages = {"com.java4coding"})

public class AppConfig {

        @Bean

        public LocalEntityManagerFactoryBean entityManagerFactory() {

                LocalEntityManagerFactoryBean factoryBean = new LocalEntityManagerFactoryBean();

                factoryBean.setPersistenceUnitName("StudentPU");

               

                return factoryBean;

        }

       

        @Bean

        public JpaTransactionManager transactionManager(EntityManagerFactory entityManagerFactory) {

                JpaTransactionManager transactionManager = new JpaTransactionManager();

                transactionManager.setEntityManagerFactory(entityManagerFactory);

               

                return transactionManager;

        }       

}

StudentRepository.java

package com.java4coding;

 

import java.util.List;

import org.springframework.data.repository.CrudRepository;

import org.springframework.data.repository.query.Param;

 

public interface  StudentRepository extends CrudRepository<Student, Long>{

}

StudentService.java

package com.java4coding;

 

import java.util.List;

import java.util.Optional;

 

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

import org.springframework.stereotype.Repository;

 

@Repository

public class StudentService {

        @Autowired

        private StudentRepository repository;

       

        public void test() {

               

                //Create

                Student student = new Student("Manu", "Manjunatha", 100L);

                repository.save(student);

                student = new Student("Advith", "Tyagraj", 100L);

                repository.save(student);

                student = new Student("Likitha", "Tyagraj", 96L);

                repository.save(student);

                student = new Student("ABC", "XYZ", 90L);

                repository.save(student);

               

                //Read All

                List<Student> students1 = (List<Student>) repository.findAll();

                students1.forEach(student1 -> System.out.println(student1));

               

                //Read by ID

                Student student2 = null;

                Optional<Student> result  = repository.findById(3L);

                if (result.isPresent()) {

                        student2 = result.get();

                        System.out.println(student2);

                }

               

                //Update

                if (student2 != null) {

                        student2.setMarks(98L);

                        repository.save(student2);

                }

               

                //Delete

                repository.delete( new Student("ABC", "XYZ", 90L));

                repository.deleteById(4L);

               

                // Count number of customer

                long count = repository.count();

                System.out.println("Number of students: " + count);

               

        }

}

Test.java

package com.java4coding;

 

import org.springframework.context.annotation.AnnotationConfigApplicationContext;

 

public class Test {

        public static void main(String[] args) {

                AnnotationConfigApplicationContext appContext = new AnnotationConfigApplicationContext();

                appContext.scan("com.java4coding");

                appContext.refresh();

 

                StudentService studentService = (StudentService) appContext.getBean("studentService");

                studentService.test();

 

                appContext.close();

        }

}

Project directory structure

spring-repository-annotation-0
 

Output in database

spring-repository-annotation-1
 

Output

Hibernate:

    insert

    into

        Student

        (firstName, lastName, marks)

    values

        (?, ?, ?)

Hibernate:

    insert

    into

        Student

        (firstName, lastName, marks)

    values

        (?, ?, ?)

Hibernate:

    insert

    into

        Student

        (firstName, lastName, marks)

    values

        (?, ?, ?)

Hibernate:

    insert

    into

        Student

        (firstName, lastName, marks)

    values

        (?, ?, ?)

Hibernate:

    select

        student0_.studentId as studentI1_0_,

        student0_.firstName as firstNam2_0_,

        student0_.lastName as lastName3_0_,

        student0_.marks as marks4_0_

    from

        Student student0_

Student [firstName=Manu, lastName=Manjunatha, Marks= 100]

Student [firstName=Advith, lastName=Tyagraj, Marks= 100]

Student [firstName=Likitha, lastName=Tyagraj, Marks= 96]

Student [firstName=ABC, lastName=XYZ, Marks= 90]

Hibernate:

    select

        student0_.studentId as studentI1_0_0_,

        student0_.firstName as firstNam2_0_0_,

        student0_.lastName as lastName3_0_0_,

        student0_.marks as marks4_0_0_

    from

        Student student0_

    where

        student0_.studentId=?

Student [firstName=Likitha, lastName=Tyagraj, Marks= 96]

Hibernate:

    select

        student0_.studentId as studentI1_0_0_,

        student0_.firstName as firstNam2_0_0_,

        student0_.lastName as lastName3_0_0_,

        student0_.marks as marks4_0_0_

    from

        Student student0_

    where

        student0_.studentId=?

Hibernate:

    update

        Student

    set

        firstName=?,

        lastName=?,

        marks=?

    where

        studentId=?

Hibernate:

    insert

    into

        Student

        (firstName, lastName, marks)

    values

        (?, ?, ?)

Hibernate:

    delete

    from

        Student

    where

        studentId=?

Hibernate:

    select

        student0_.studentId as studentI1_0_0_,

        student0_.firstName as firstNam2_0_0_,

        student0_.lastName as lastName3_0_0_,

        student0_.marks as marks4_0_0_

    from

        Student student0_

    where

        student0_.studentId=?

Hibernate:

    delete

    from

        Student

    where

        studentId=?

Hibernate:

    select

        count(*) as col_0_0_

    from

        Student student0_

Number of students: 3

 

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