Spring Boot 데이터 생성 with JPA

데이터베이스는 데이터를 관리하는 창고

JPA : 자바언어를 DB가 이해할수있는 기능

DTO를 Etity로 변환하고 Repository를 통해 DB까지 저장해보자

 

./controller/ArticleController

ArticleController생성

package com.example.firstproject.controller;

import com.example.firstproject.dto.ArticleForm;
import com.example.firstproject.entity.Article;
import com.example.firstproject.repository.ArticleRepository;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PostMapping;

@Controller
public class ArticleController {

    @GetMapping("/articles/new")
    public String newArticleForm(){
        return "articles/new";
    }

    @PostMapping("/articles/create")
    public String createArticle(ArticleForm form){
        System.out.println(form.toString());
        //1. DTO를 Entity로 변환
        Article article = form.toEntity();
        System.out.println(article.toString());
        //2. Repository에게 Entity를 DB안에 저장
        Article saved = articleRepository.save(article);
        System.out.println(saved.toString());
        return "";
    }
}

엔티티 작성하기

../entity/Article

package com.example.firstproject.entity;

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

@Entity // DB가 해당 객체를 인식 가능하게 한다
public class Article {

    @Id // 대표값을 지정한다 like 주민번호
    @GeneratedValue //1,2,3,... 자동생성 어노테이션!
    private Long id;

    @Column
    private String title;
    @Column
    private String content;

    public Article(Long id, String title, String content) {
        this.id = id;
        this.title = title;
        this.content = content;
    }

    @Override
    public String toString() {
        return "Article{" +
                "id=" + id +
                ", title='" + title + '\'' +
                ", content='" + content + '\'' +
                '}';
    }
}

변환메소드 추가

../dto/ArticleForm

package com.example.firstproject.dto;

import com.example.firstproject.entity.Article;

public class ArticleForm {

    private String title;
    private String content;
    public ArticleForm(String title, String content) {
        this.title = title;
        this.content = content;
    }
    @Override
    public String toString() {
        return "ArticleForm{" +
                "title='" + title + '\'' +
                ", content='" + content + '\'' +
                '}';
    }

    public Article toEntity() {
        return new Article(null,title,content);
    }
}

리파지터리를 통한 엔티티 저장하기

../controller/ArticleController

package com.example.firstproject.controller;

import com.example.firstproject.dto.ArticleForm;
import com.example.firstproject.entity.Article;
import com.example.firstproject.repository.ArticleRepository;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PostMapping;

@Controller
public class ArticleController {

    @Autowired //스프링 부트가 미리 생성해놓은 객체를 가져다가 자동연결!
    private ArticleRepository articleRepository;

    @GetMapping("/articles/new")
    public String newArticleForm(){
        return "articles/new";
    }

    @PostMapping("/articles/create")
    public String createArticle(ArticleForm form){
        System.out.println(form.toString());
        //1. DTO를 Entity로 변환
        Article article = form.toEntity();
        System.out.println(article.toString());
        //2. Repository에게 Entity를 DB안에 저장
        Article saved = articleRepository.save(article);
        System.out.println(saved.toString());
        return "";
    }
}

리파지터리 작성

../repository/ArticleRepository

package com.example.firstproject.repository;

import com.example.firstproject.entity.Article;
import org.springframework.data.repository.CrudRepository;

public interface ArticleRepository extends CrudRepository<Article,Long> {
// CrudRepository<관리대상 엔티티: Article, 대표값의 타입(id) : Long>
}

의존성(DI)주입하기

데이터 저장 흐름 확인

../controller/ArticleController

package com.example.firstproject.controller;

import com.example.firstproject.dto.ArticleForm;
import com.example.firstproject.entity.Article;
import com.example.firstproject.repository.ArticleRepository;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PostMapping;

@Controller
public class ArticleController {

    @Autowired //스프링 부트가 미리 생성해놓은 리파지터리 객체를 가져옴(DI)
    private ArticleRepository articleRepository;

    @GetMapping("/articles/new")
    public String newArticleForm(){
        return "articles/new";
    }

    @PostMapping("/articles/create")
    public String createArticle(ArticleForm form){
        System.out.println(form.toString());
        //1. DTO를 Entity로 변환
        Article article = form.toEntity();
        System.out.println(article.toString());
        //2. Repository에게 Entity를 DB안에 저장
        Article saved = articleRepository.save(article);
        System.out.println(saved.toString());
        return "";
    }
}

동작 확인

 

값이 잘 입력하였다!