SpringBootで簡単なCRUDアプリの作成手順を解説しています

spring.datasource.url=jdbc:mysql://${MYSQL_HOST:localhost}:3306/DBの名前
spring.datasource.username=ご自身の名前
spring.datasource.password=ご自身のパスワード
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver
spring.sql.init.encoding=utf-8
spring.sql.init.mode=always

package com.app.progTrack.entity;

import java.sql.Timestamp;
import java.time.LocalDateTime;

import jakarta.persistence.Column;
import jakarta.persistence.Entity;
import jakarta.persistence.GeneratedValue;
import jakarta.persistence.GenerationType;
import jakarta.persistence.Id;
import jakarta.persistence.Table;
import lombok.Data;

@Entity
@Table(name = "study_times")
@Data
public class StudyTime {
	@Id
	@GeneratedValue(strategy = GenerationType.IDENTITY)
	@Column(name = "study_times_id")
	private Long studyTimesId;
	
	@Column(name = "start_time")
	private LocalDateTime startTime;
	
	@Column(name = "end_time")
	private LocalDateTime endTime;
	
	@Column(name = "created_at", insertable = false, updatable = false)
	private Timestamp createdAt;
	
	@Column(name = "updated_at", insertable = false, updatable = false)
	private Timestamp updatedAt;
}

package com.app.progTrack.repository;

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

import com.app.progTrack.entity.StudyTime;

public interface StudyTimeRepository extends JpaRepository<StudyTime, Long>{

}

package com.app.progTrack.service;

import java.time.LocalDateTime;
import java.util.List;

import org.springframework.stereotype.Service;

import com.app.progTrack.entity.StudyTime;
import com.app.progTrack.repository.StudyTimeRepository;

@Service
public class StudyTimeService {
	private final StudyTimeRepository studyTimeRepository;
	
	public StudyTimeService(StudyTimeRepository studyTimeRepository) {
		this.studyTimeRepository = studyTimeRepository;
	}
	
	// 学習時間の打刻セットロジック
	public void saveStudyTime(StudyTime studyTime) {

		if (studyTime.getStartTime() == null) {
			studyTime.setStartTime(LocalDateTime.now());
		}
		
		if (studyTime.getEndTime() == null) {
			studyTime.setEndTime(LocalDateTime.now());
		}
		
		studyTimeRepository.save(studyTime);
	}
	// 一覧ページ表示用
	public List<StudyTime> getAllStudyTimes() {
		return studyTimeRepository.findAll();
	}
	// 編集用
	public StudyTime getStudyTime(Long id) {
		return studyTimeRepository.findById(id).orElse(null);
	}
	// 削除用
	public void deleteStudyTime(Long id) {
		studyTimeRepository.deleteById(id);
	}
}

package com.app.progTrack.controller;

import java.util.List;

import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.ModelAttribute;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestMapping;

import com.app.progTrack.entity.StudyTime;
import com.app.progTrack.service.StudyTimeService;

@Controller
@RequestMapping("/studytime")
public class StudyTimeController {
	private final StudyTimeService studyTimeService;
	
	public StudyTimeController(StudyTimeService studyTimeService) {
		this.studyTimeService = studyTimeService;
	}
	
	@GetMapping
	public String listStudyTimes(Model model) {
		List<StudyTime> studyTimes = studyTimeService.getAllStudyTimes();
		model.addAttribute("studyTimes", studyTimes);
		return "studytime/studyTimeList";
	}
	
	@GetMapping("/new")
	public String newStudyTimeForm(Model model) {
		model.addAttribute("studyTimeObject", new StudyTime());
		return "studytime/studyTimeForm";
	}
	
	@PostMapping
	public String createStudyTime(@ModelAttribute StudyTime studyTime) {
		studyTimeService.saveStudyTime(studyTime);
		return "redirect:/studytime";
	}
	
	@GetMapping("/{id}/edit")
	public String editStudyTimeForm(@PathVariable Long id, Model model) {
		StudyTime studyTime = studyTimeService.getStudyTime(id);
		model.addAttribute("studyTimeObject", studyTime);
		return "studytime/studyTimeForm";
	}
	
	@PostMapping("/{id}")
	public String updateStudyTime(@PathVariable Long id, @ModelAttribute StudyTime studyTime) {
		studyTime.setStudyTimesId(id);
		studyTimeService.saveStudyTime(studyTime);
		return "redirect:/studytime";
	}
	
	@PostMapping("/{id}/delete")
	public String deleteStudyTime(@PathVariable Long id) {
		studyTimeService.deleteStudyTime(id);
		return "redirect:/studytime";
	}
}

<!DOCTYPE html>
<html xmlns:th="http://www.thymeleaf.org">
<head>
	<meta charset="UTF-8">
	<title>学習時間の入力</title>
	<script>
		function setCurrentTime(field) {
			const now = new Date();
			const formattedTime = now.toISOString().slice(0, 16);
			document.getElementById(field).value = formattedTime;
		}
	</script>
</head>
<body>
	<h1>学習時間の入力</h1>
	<form th:action="@{/studytime}" th:object="${studyTimeObject}" method="post">
		<label>開始時間:</label>
		<input type="datetime-local" id="startTime" th:field="*{startTime}" required />
		<button type="button" onclick="setCurrentTime('startTime')">学習開始</button>
		
		<label>終了時間</label>
		<input type="datetime-local" id="endTime" th:field="*{endTime}" required />
		<button type="button" onclick="setCurrentTime('endTime')">学習終了</button>
		
		<button type="submit">保存</button>
	</form>
	
	<a href="/studytime">戻る</a>
</body>
</html>

<!DOCTYPE html>
<html xmlns:th="http://www.thymeleaf.org">
<head>
	<meta charset="UTF-8">
	<title>学習時間一覧</title>
</head>
<body>
	<h1>学習時間一覧</h1>
	<a th:href="@{/studytime/new}">学習を開始する</a>
	<table>
		<tr>
			<th>ID</th>
			<th>開始時間</th>
			<th>終了時間</th>
		</tr>
		<tr th:each="studyTime : ${studyTimes}">
			<td th:text="${studyTime.studyTimesId}"></td>
			<td th:text="${studyTime.startTime}"></td>
			<td th:text="${studyTime.endTime}"></td>
			<td>
				<a th:href="@{/studytime/{id}/edit(id=${studyTime.studyTimesId})}">編集</a>
				<form th:action="@{/studytime/{id}/delete(id=${studyTime.studyTimesId})}" method="post" style="display: inline;">
					<button type="submit">削除</button>
				</form>
			</td>
		</tr>
	</table>
</body>
</html>