MS - Springboot + Hibernate + Rest web service chapter 1

 Create a simple REST web service using springboot.

Use spring initializer   https://start.spring.io/

Dependencies

Web, JPA, database ( Mysql Connctor ) 

for your wish you can use, lombok, actuator, devtools

Webservice will include simple CRUD operation alias with REST POST,GET, PUT, GET

Tech Stack

Java 8, Maven, Springboot 3.10 , 

Sample code as below

POM file

<?xml version="1.0" encoding="UTF-8"?>
<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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
   <modelVersion>4.0.0</modelVersion>
   <parent>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-parent</artifactId>
      <version>3.1.0</version>
      <relativePath/> <!-- lookup parent from repository -->
   </parent>
   <groupId>com.demo.micro</groupId>
   <artifactId>student</artifactId>
   <version>0.0.1-SNAPSHOT</version>
   <name>student</name>
   <description>Student Service</description>
   <properties>
      <java.version>17</java.version>
   </properties>
   <dependencies>
      <dependency>
         <groupId>org.springframework.boot</groupId>
         <artifactId>spring-boot-starter-actuator</artifactId>
      </dependency>
      <dependency>
         <groupId>org.springframework.boot</groupId>
         <artifactId>spring-boot-starter-data-jpa</artifactId>
      </dependency>
      <dependency>
         <groupId>org.springframework.boot</groupId>
         <artifactId>spring-boot-starter-web</artifactId>
      </dependency>
      <dependency>
         <groupId>mysql</groupId>
         <artifactId>mysql-connector-java</artifactId>
         <version>8.0.31</version>
      </dependency>
      <dependency>
         <groupId>org.projectlombok</groupId>
         <artifactId>lombok</artifactId>
         <optional>true</optional>
      </dependency>

      <dependency>
         <groupId>org.springframework.boot</groupId>
         <artifactId>spring-boot-devtools</artifactId>
         <scope>runtime</scope>
         <optional>true</optional>
      </dependency>
      <dependency>
         <groupId>org.springframework.boot</groupId>
         <artifactId>spring-boot-starter-test</artifactId>
         <scope>test</scope>
      </dependency>
   </dependencies>

   <build>
      <plugins>
         <plugin>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-maven-plugin</artifactId>
         </plugin>
      </plugins>
   </build>

</project>

Application properties

server.port=8203
spring.datasource.url=jdbc:mysql://localhost:3306/student_mgt
spring.datasource.username=root
spring.datasource.password=root

# for Spring Boot 2
# spring.jpa.properties.hibernate.dialect= org.hibernate.dialect.MySQL5InnoDBDialect
# for Spring Boot 3
spring.jpa.properties.hibernate.dialect= org.hibernate.dialect.MySQLDialect
spring.jpa.show-sql=false
spring.jpa.generate-ddl=true
# Hibernate ddl auto (create, create-drop, validate, update)
spring.jpa.hibernate.ddl-auto=update
spring.jpa.hibernate.naming.physical-strategy=org.hibernate.boot.model.naming.PhysicalNamingStrategyStandardImpl

Code base Structure

com.demo.micro.student

controller --> will include REST API

model --> model classes

repository --> repo file, db connection

service --> service classes

MainApllication --> StudentApplication with @SpringBootApplication

Controller

package com.demo.micro.student.controller;

import com.demo.micro.student.model.Student;
import com.demo.micro.student.service.StudentServiceImpl;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.*;

import java.util.List;
import java.util.Optional;

@RestController
@RequestMapping("/students")
public class StudentController {

    @Autowired
    StudentServiceImpl studentService;

    @GetMapping("")
    public ResponseEntity<List<Student>> list() {
        return new ResponseEntity<List<Student>>(studentService.list(), HttpStatus.OK);
    }

    @PostMapping("")
    public ResponseEntity<Student> resgiterStudent(@RequestBody Student student) {
        try {
            Student st = studentService.createStudent(student);
            return new ResponseEntity<>(st, HttpStatus.CREATED);
        } catch (Exception e) {
            return new ResponseEntity<>(null, HttpStatus.INTERNAL_SERVER_ERROR);
        }
    }

    @PutMapping("")
    public ResponseEntity<Student> updateStudent(@RequestBody Student student) {
        return new ResponseEntity<>(studentService.createStudent(student), HttpStatus.OK);
    }

    @PutMapping("/{id}")
    public ResponseEntity<Student> updateStudent(@PathVariable("id") int id, @RequestBody Student student) {
        Optional<Student> st = studentService.findById(id);
        if (st.isPresent()) {
            // set details for student
            return new ResponseEntity<>(studentService.createStudent(student), HttpStatus.OK);
        } else {
            return new ResponseEntity<>(HttpStatus.NOT_FOUND);
        }
    }

    /**
     * Don't do this. We normally makes a soft delete -
     * 1. update flag/property as deleted. But flag is redundant field
     * 2. use date/time option. nullable date time or default old time.
     *
     * @param student
     * @return
     */
    @DeleteMapping("")
    public ResponseEntity<Student> deleteStudent(@RequestBody Student student) {
        studentService.deleteStudent(student);
        return new ResponseEntity<>(null, HttpStatus.ACCEPTED);
    }
}

Model

package com.demo.micro.student.model;

import jakarta.persistence.*;
import lombok.Data;

/**
 * Student details.
 */
@Entity
@Table(name = "student")
@Data
public class Student {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    @Column(name = "student_id")
    private int studentId;

    /**
     * First name of the student.
     */
    @Column(name = "first_name")
    private String firstName;

    /**
     * Last name of the student.
     */
    @Column(name = "last_name")
    private String lastName;


}

Repository

package com.demo.micro.student.repository;

import com.demo.micro.student.model.Student;
import org.springframework.data.jpa.repository.JpaRepository;

public interface StudentRepository extends JpaRepository<Student,Integer> {
}

Service classes - Interface and Impl

package com.demo.micro.student.service;

import com.demo.micro.student.model.Student;

import java.util.List;
import java.util.Optional;

/**
 *
 */
public interface StudentService {

    /**
     * Returns a list of {@link Student}s.
     * @return list of {@link Student}
     */
    List<Student> list();
    Student createStudent(Student student);

    Optional<Student> findById(int studentId);

    void deleteStudent(Student student);
}

package com.demo.micro.student.service;

import com.demo.micro.student.model.Student;
import com.demo.micro.student.repository.StudentRepository;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import java.util.List;
import java.util.Optional;

@Service
public class StudentServiceImpl implements StudentService {

    @Autowired
    StudentRepository studentRepository;

    /**
     * List all the {@link Student}
     *
     * @return
     */
    @Override
    public List<Student> list() {
        return studentRepository.findAll();
    }

    /**
     * Create a new record of {@link Student}.
     *
     * @param student
     * @return
     */
    @Override
    public Student createStudent(Student student) {
        return studentRepository.save(student);
    }

    @Override
    public Optional<Student> findById(int studentId) {
        return studentRepository.findById(studentId);
    }

    public void deleteStudent(Student student) {
        studentRepository.delete(student);
    }

}

Important : Note that we put @Srvivie at Impl class, not Interface

Main class

package com.demo.micro.student;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class StudentApplication {

   public static void main(String[] args) {
      SpringApplication.run(StudentApplication.class, args);
   }

}