Spring boot hello world (2)

H2, Hibernate 연동

H2 dependency 추가

build.gradle 파일

dependencies {
 ...
 compile("com.h2database:h2:1.4.193")
 ...
}

dependency를 추가하고 gradle project refresh한다.

Application 설정

spring.h2.console.enabled=true
spring.h2.console.path=/h2
spring.datasource.url=jdbc:h2:file:C:\Users\git\helloworld\h2_db;AUTO_SERVER=TRUE

#spring.datasource.url=jdbc:h2:mem:testdb
spring.datasource.driverClassName=org.h2.Driver
spring.datasource.username=sa
spring.datasource.password=
#spring.jpa.database-platform=org.hibernate.dialect.H2Dialect

설정하고 브라우져에서 h2 관리콘솔 접속했더니 아래와 같은 에러가 뜬다.

Caused by: java.lang.IllegalStateException: Unsupported type 17 [1.4.200/3]

H2 버전도 바꿔보고,  URL도 바꿔보고, 계정도 바꿔보고 별짓을 해도 안되더니 혹시나 해서 cmd에서 gradle로 빌드하고 jar를 실행했더니 잘된다!!!! 뻑킹 뭐야!!!!

그러고 나서 다시 이클립스에서 spring boot 프로젝트를 중지했다가 재시작하니 잘되네??

뭔가 이클립스 스프링 플러그인이 굉장히 불안한거 같다.

테이블, 데이터 생성

H2 관리 콘솔에서 테이블, 데이터를 생성한다.

DROP TABLE IF EXISTS TBL_EMPLOYEES;
  
CREATE TABLE TBL_EMPLOYEES (
  id INT AUTO_INCREMENT  PRIMARY KEY,
  first_name VARCHAR(250) NOT NULL,
  last_name VARCHAR(250) NOT NULL,
  email VARCHAR(250) DEFAULT NULL
);

INSERT INTO TBL_EMPLOYEES (first_name, last_name, email) VALUES
  ('Lokesh', 'Gupta', 'abc@gmail.com'),
  ('Deja', 'Vu', 'xyz@email.com'),
  ('Caption', 'America', 'cap@marvel.com');

귀찮으니 그냥 sa 계정에서...

Hibernate 추가

build.gradle 파일

dependencies {
  ...
  compile("org.hibernate:hibernate-core:5.4.9.Final")
  ...
}

dependency를 추가하고 gradle project refresh한다.

소스코드 작성

Entity

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.Table;

import org.apache.commons.lang3.builder.ToStringBuilder;
import org.apache.commons.lang3.builder.ToStringStyle;

@Entity
@Table(name="TBL_EMPLOYEES")
public class Employee {
 
 @Id
 @GeneratedValue
 private Long id;
 
 @Column(name = "first_name")
 private String firstName;
 
 @Column(name = "last_name")
 private String lastName;
 
 @Column(name="email", nullable=false, length=200)
 private String email;
  
 //add getter, setter

 @Override
 public String toString() {
  return ToStringBuilder.reflectionToString(this, ToStringStyle.SHORT_PREFIX_STYLE);
 }
}

ToStringBuilder class를 사용하기 위해 org.apache.commons.lang3 패키지를 추가하였다.

dependencies {
 ...
 compile("org.apache.commons:commons-lang3:3.9")
 ...
}

Repository

import org.springframework.data.jpa.repository.JpaRepository;

import com.ha.helloworld.entity.Employee;

public interface EmployeeRespository extends JpaRepository{

}

Service

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

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

import com.ha.helloworld.entity.Employee;
import com.ha.helloworld.repository.EmployeeRespository;

@Service
public class EmployeeService {

 @Autowired
 EmployeeRespository repository;
 
 public List getAllEmployees() {
  List list = this.repository.findAll();
  
  if(list == null) return new ArrayList();
  
  return list;
 }
 
 public Employee getEmployeeById(Long id) {
  if(id == null) return null;
  
  Optional option = this.repository.findById(id);
  
  if(option.isPresent()) return option.get();
  
  return null;
 }
 
 public Employee createOrUpdateEmployee(Employee entity) {
  
  Employee data = this.getEmployeeById(entity.getId());
  
  if(data == null) data = new Employee();
  
  data.setFirstName(entity.getFirstName());
  data.setLastName(entity.getLastName());
  data.setEmail(entity.getEmail());
  
  this.repository.save(data);
  
  return data;
 }
 
 public void deleteEmployeeById(Long id) {
  this.repository.deleteById(id);
 }
}

Controller

import java.util.List;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.HttpHeaders;
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.DeleteMapping;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestMapping;

import com.ha.helloworld.entity.Employee;
import com.ha.helloworld.service.EmployeeService;

@Controller
@RequestMapping("/employee")
public class EmployeeController {

 @Autowired
 EmployeeService employeeService;
 
 @GetMapping
 public ResponseEntity> getAllEmployee() {
  List list = this.employeeService.getAllEmployees();
  
  ResponseEntity> response = new ResponseEntity<>(list, new HttpHeaders(), HttpStatus.OK);
  
  return response;
 }
 
 @GetMapping("/{id}")
    public ResponseEntity getEmployeeById(@PathVariable("id") Long id) {
        Employee entity = employeeService.getEmployeeById(id);
 
        return new ResponseEntity(entity, new HttpHeaders(), HttpStatus.OK);
    }
 
    @PostMapping
    public ResponseEntity createOrUpdateEmployee(Employee employee) {
        Employee updated = employeeService.createOrUpdateEmployee(employee);
        return new ResponseEntity(updated, new HttpHeaders(), HttpStatus.OK);
    }
 
    @DeleteMapping("/{id}")
    public ResponseEntity deleteEmployeeById(@PathVariable("id") Long id) {
     employeeService.deleteEmployeeById(id);
        return ResponseEntity.ok().build();
    }
}

Rest API 형식이라 Postman 프로그램으로 호출 테스트 해보았다.

http://localhost/employee

결과는 아래 처럼 나옴

[
    {
        "id": 1,
        "firstName": "Lokesh",
        "lastName": "Gupta",
        "email": "abc@gmail.com"
    },
    {
        "id": 2,
        "firstName": "Deja",
        "lastName": "Vu",
        "email": "xyz@email.com"
    },
    {
        "id": 3,
        "firstName": "Caption",
        "lastName": "America",
        "email": "cap@marvel.com"
    }
]

데이터 추가 API를 호출하면 아래와 같은 오류가 난다.

2019-12-13 01:07:41 - Sequence "HIBERNATE_SEQUENCE" not found; SQL statement:
call next value for hibernate_sequence [90036-193]
2019-12-13 01:07:59 - Failed to complete request: org.springframework.orm.jpa.JpaSystemException: could not prepare statement; nested exception is org.hibernate.exception.GenericJDBCException: could not prepare statement
2019-12-13 01:07:59 - Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Request processing failed; nested exception is org.springframework.orm.jpa.JpaSystemException: could not prepare statement; nested exception is org.hibernate.exception.GenericJDBCException: could not prepare statement] with root cause
org.h2.jdbc.JdbcSQLException: Sequence "HIBERNATE_SEQUENCE" not found; SQL statement:
call next value for hibernate_sequence [90036-193]
 at org.h2.message.DbException.getJdbcSQLException(DbException.java:345)
 at org.h2.message.DbException.get(DbException.java:179)
 at org.h2.message.DbException.get(DbException.java:155)

엔티티에 아이디 생성 annotation아래와 같이 설정하면 JPA는 default로 id를 "HIBERNATE_SEQUENCE"라는 sequence table에서 가져오려고 한다. sequence table 만들지 않았으므로 오류가 나는것.

@Id
 @GeneratedValue
 private Long id;

그래서 id 생성을 strategy를 통해 생성하도록 아래와 같이 설정하면 오류가 발생하지 않는다.

@Id
 @GeneratedValue(strategy = GenerationType.IDENTITY)
 private Long id;

참고: https://howtodoinjava.com/spring-boot2/spring-boot-crud-hibernate/