In this article, we will see about Spring Data JPA CrudRepository findById() Example using Spring Boot and oracle.
Spring Data JPA Interview Questions and Answers
How to write a custom method in the repository in Spring Data JPA
The findById() method is used to retrieves an entity by its id and it is available in CrudRepository interface. The CrudRepository extends Repository interface. In Spring Data JPA Repository is top-level interface in the hierarchy. Here we are going to see the findById() method of CrudRepository. The findById() method has been defined as below.
Optional<T> findById(ID id);
Note – Optional is a class introduced in java 8.
Using findById() method we can get a single record(entity) on basis of id.
Internally findById() method use EntityManger’s find() method(as below).
public Optional<T> findById(ID id) {
// some more code
if (metadata == null) {
return Optional.ofNullable(em.find(domainType, id));
}
//some more code
return Optional.ofNullable(type == null ? em.find(domainType, id, hints) : em.find(domainType, id, type, hints));
}
Let’s see in below code how to use the Spring Data JPA CrudRepository findById() method for get operation.
package com.javatute.impl;
import java.util.Optional;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;
import com.javatute.entity.Student;
import com.javatute.repository.StudentRepository;
import com.javatute.service.StudentService;
@Service("studentServiceImpl")
public class StudentServiceImpl implements StudentService {
@Autowired
private StudentRepository studentRepository;
@Transactional
public Student saveStudent(Student student) {
Student response = studentRepository.save(student);
return response;
}
@Transactional(readOnly = true)
public Student getStudent(int id ) {
Optional<Student> studentResponse = studentRepository.findById(id);
Student student = studentResponse.get();
return student;
}
}
Let’s see an example of Spring Data JPA CrudRepository findById() Example where we will use save() method for creating the entity and findById() to get a single record.
Open eclipse and create maven project, Don’t forget to check ‘Create a simple project (skip)’ click on next. Fill all details(GroupId – springdatafindbyid, ArtifactId – springdatafindbyid and name – springdatafindbyid) and click on finish. Keep packaging as the jar.
Modify pom.xml
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>springdatafindbyid</groupId>
<artifactId>springdatafindbyid</artifactId>
<version>0.0.1-SNAPSHOT</version>
<name>springdatafindbyid</name>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.0.2.RELEASE</version>
</parent>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-jpa</artifactId>
</dependency>
<dependency>
<groupId>com.oracle</groupId>
<artifactId>ojdbc6</artifactId>
<version>11.2.0.3</version>
</dependency>
</dependencies>
<build>
<finalName>${project.artifactId}</finalName>
<plugins>
<plugin>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.1</version>
<configuration>
<fork>true</fork>
<executable>C:\Program Files\Java\jdk1.8.0_131\bin\javac.exe</executable>
</configuration>
</plugin>
</plugins>
</build>
</project>
Note – In pom.xml we have defined javac.exe path in configuration tag. You need to change accordingly i.e where you have installed JDK.
If you see any error for oracle dependency then follow these steps.
Directory structure –
Student.java
package com.javatute.entity;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
@Entity
public class Student {
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private int id;
@Column(name = "name")
private String name;
@Column(name = "roll_number")
private String rollNumber;
@Column(name = "university")
String university;
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 getRollNumber() {
return rollNumber;
}
public void setRollNumber(String rollNumber) {
this.rollNumber = rollNumber;
}
public String getUniversity() {
return university;
}
public void setUniversity(String university) {
this.university = university;
}
}StudentController.java
package com.javatute.controller;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.bind.annotation.RestController;
import com.javatute.entity.Student;
import com.javatute.service.StudentService;
@RestController
@RequestMapping(value = "/student")
public class StudentController {
@Autowired
private StudentService studentService;
@RequestMapping(value = "/save", method = RequestMethod.POST)
@ResponseBody
public Student save(@RequestBody Student student) {
Student studentResponse = (Student) studentService.saveStudent(student);
return studentResponse;
}
@RequestMapping(value = "/{id}", method = RequestMethod.GET)
@ResponseBody
public Student getStudent(@PathVariable int id) {
Student studentResponse = (Student) studentService.getStudent(id);
return studentResponse;
}
}
StudentRepository.java – interface
package com.javatute.repository;
import java.io.Serializable;
import org.springframework.data.repository.CrudRepository;
import org.springframework.stereotype.Repository;
import com.javatute.entity.Student;
@Repository
public interface StudentRepository extends CrudRepository<Student, Serializable> {
}
StudentService.java – interface
package com.javatute.service;
import org.springframework.stereotype.Component;
import com.javatute.entity.Student;
@Component
public interface StudentService {
public Student saveStudent(Student student);
public Student getStudent(int id);
}
StudentServiceImpl.java
package com.javatute.impl;
import java.util.Optional;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;
import com.javatute.entity.Student;
import com.javatute.repository.StudentRepository;
import com.javatute.service.StudentService;
@Service("studentServiceImpl")
public class StudentServiceImpl implements StudentService {
@Autowired
private StudentRepository studentRepository;
@Transactional
public Student saveStudent(Student student) {
Student response = studentRepository.save(student);
return response;
}
@Transactional(readOnly = true)
public Student getStudent(int id ) {
Optional<Student> studentResponse = studentRepository.findById(id);
Student student = studentResponse.get();
return student;
}
}
SpringMain.java
package com.javatute.main;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.autoconfigure.domain.EntityScan;
import org.springframework.context.annotation.ComponentScan;
@SpringBootApplication
@ComponentScan(basePackages = "com.*")
@EntityScan("com.javatute.entity")
public class SpringMain {
public static void main(String[] args) {
SpringApplication.run(SpringMain.class, args);
}
}
JpaConfig.java
package com.javatute.config;
import org.springframework.context.annotation.Configuration;
import org.springframework.data.jpa.repository.config.EnableJpaRepositories;
@Configuration
@EnableJpaRepositories(basePackages = "com.javatute.repository")
public class JpaConfig {
}
application.properties
# Connection url for the database spring.datasource.url=jdbc:oracle:thin:@localhost:1521:XE spring.datasource.username=SYSTEM spring.datasource.password=oracle2 spring.datasource.driver-class-name=oracle.jdbc.driver.OracleDriver # Show or not log for each sql query spring.jpa.show-sql = true spring.jpa.hibernate.ddl-auto =create spring.jpa.properties.hibernate.dialect = org.hibernate.dialect.Oracle10gDialect server.port = 9091
Let’s run the SpringMain class(run as java application).
Perform save operation first using below REST API.
http://localhost:9091/student/save
Request Data –
{
"name": "Hiteshdo",
"rollNumber": "0126CS01",
"university": "rgtu"
}
Response data –
{
"id": 1,
"name": "Hiteshdo",
"rollNumber": "0126CS01",
"university": "rgtu"
}
Get operation.
API -http://localhost:9091/student/{id}
http://localhost:9091/student/1
See brief about Spring Data JPA Repository hierarchy as below.
You may like.
- Spring Data CrudRepository saveAll() and findAll().
- Spring Data CrudRepository save() Method.
- Sorting in Spring Data JPA using Spring Boot.
- Spring Data JPA example using spring boot.
- Spring Data JPA and its benefit.
Other Spring Data JPA and Hibernate tutorials.
- @Version Annotation Example In Hibernate.
- Hibernate Validator Constraints Example Using Spring Boot.
- @Temporal Annotation Example In Hibernate/Jpa Using Spring Boot.
- Hibernate Table Per Concrete Class Spring Boot.
- Hibernate Table Per Subclass Inheritance Spring Boot.
- Hibernate Single Table Inheritance using Spring Boot.
- One To One Mapping Annotation Example in Hibernate/JPA using Spring Boot and Oracle.
- One To One Bidirectional Mapping Example In Hibernate/JPA Using Spring Boot and Oracle.
- One To Many Mapping Annotation Example In Hibernate/JPA Using Spring Boot And Oracle.
- Many To One Unidirectional Mapping In Hibernate/JPA Annotation Example Using Spring Boot and Oracle.
- One To Many Bidirectional Mapping In Hibernate/JPA Annotation Example Using Spring Boot and Oracle.
- Many To Many Mapping Annotation Example In Hibernate/JPA Using Spring Boot And
Spring Data JPA findById() docs.
