[JAVA] Create a simple search app with Spring Boot

As the title suggests, I created a search app.

usage environment

・ Windows10 (64bit) ・ Spring-boot: 2.2.6 -Eclipse: 4.9.0 ・ H2

Completion screen

When you enter any or all of the genre, author, title Pull the contents at the bottom of the screen. image.png



import javax.persistence.Entity;
import javax.persistence.Id;

public class BookData {

	private long isbn;

	private String genre;
	private String author;
	private String title;
	private int stock;
	private Boolean status;

	public long getIsbn() {
		return isbn;
	public void setIsbn(long isbn) {
		this.isbn = isbn;
	public String getGenre() {
		return genre;
	public void setGenre(String genre) {
		this.genre = genre;
	public String getAuthor() {
		return author;
	public void setAuthor(String author) {
		this.author = author;
	public String getTitle() {
		return title;
	public void setTitle(String title) {
		this.title = title;
	public int getStock() {
		return stock;
	public void setStock(int stock) {
		this.stock = stock;
	public Boolean getStatus() {
		return status;
	public void setStatus(Boolean status) {
		this.status = status;

Dao Prepare a Dao class to search by genre, author, and title.


import java.io.Serializable;
import java.util.List;

public interface BookDataDao extends Serializable {

	public List<BookData> search(String genre, String author, String title);

Repository Create a BookDataDaoImpl that implements the Dao class. Please refer to the comments for the contents of each description.


import java.util.List;

import javax.persistence.EntityManager;
import javax.persistence.Query;

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

public class BookDataDaoImpl implements BookDataDao {

	//Providing the functions required to use Entity
	private EntityManager entityManager;

	public BookDataDaoImpl() {

	public BookDataDaoImpl(EntityManager manager) {
		entityManager = manager;

	//Override the search method provided by Dao class
	public List<BookData> search(String genre, String author, String title) {

		//Concatenate SQL statements with StringBuilder
		StringBuilder sql = new StringBuilder();
		sql.append("SELECT b From BookData b WHERE ");

		boolean genreFlg  = false;
		boolean authorFlg = false;
		boolean titleFlg  = false;
		boolean andFlg    = false;

		//Append to sql variable if genre is not blank
		//Set the flag to true
		if(!"".equals(genre)) {
			sql.append("b.genre LIKE :genre");
			genreFlg = true;
			andFlg   = true;

		//append to sql variable if author is not blank
		//Set the flag to true
		if(!"".equals(author)) {
			if (andFlg) sql.append(" AND ");
			sql.append("b.author LIKE :author");
			authorFlg = true;
			andFlg    = true;

		//Append to sql variable if title is not blank
		//Set the flag to true
		if(!"".equals(title)) {
			if (andFlg) sql.append(" AND ");
			sql.append("b.title LIKE :title");
			titleFlg = true;
			andFlg   = true;

Query has a function equivalent to a query statement for querying data with SQL
Use entityManager's createQuery method
Pass sql variable as an argument
	    Query query = entityManager.createQuery(sql.toString());

	    //If the above if statement is true, set a value for each variable
	    //This time, I want to do an ambiguous search, so I use the like clause
	    if (genreFlg) query.setParameter("genre", "%" + genre + "%");
	    if (authorFlg) query.setParameter("author", "%" + author + "%");
	    if (titleFlg) query.setParameter("title", "%" + title + "%");
	    return query.getResultList();



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

public interface BookDataRepository extends JpaRepository<BookData, Long> {




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

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

public class BookService {

	private BookDataRepository bookDataRepository;

	private BookDataDaoImpl bookDataDaoImpl;

	//Search all
	public List<BookData> findAll(){
		return bookDataRepository.findAll();

	//Find the corresponding ID
	public Optional<BookData> findById(long isbn) {
        return bookDataRepository.findById(isbn);

	public BookData save(BookData bookData) {
		return bookDataRepository.saveAndFlush(bookData);

	public List<BookData> search(String genre, String author, String title){

		List<BookData> result = new ArrayList<BookData>();

		//If all are blank, search all
		if ("".equals(genre) && "".equals(author) && "".equals(title)){
			result = bookDataRepository.findAll();
		else {
			//Other than the above, call the method of BookDataDaoImpl
			result = bookDataDaoImpl.search(genre, author, title);
		return result;



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

import javax.annotation.PostConstruct;
import javax.persistence.EntityManager;
import javax.persistence.PersistenceContext;

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

public class StockController {

	private BookService bookService;

	EntityManager entityManager;

	//List display processing
	public String index(Model model,@ModelAttribute("formModel") BookData bookdata) {

		model.addAttribute("msg", "Inventory control");
		model.addAttribute("msg2", "Please enter your search criteria");
		List<BookData> books = bookService.findAll();
		model.addAttribute("books", books);

		return "index";

	//Search result receiving process
	//@Receive formModel from form with ModelAttribute
	//That type(BookData)And variables(bookdata)To specify
	public String select(@ModelAttribute("formModel") BookData bookdata, Model model) {

		model.addAttribute("msg", "search results");
		//Get each value with the getter of bookdata
		List<BookData> result = bookService.search(bookdata.getGenre(),bookdata.getAuthor(), bookdata.getTitle());
		model.addAttribute("books", result);

		return "index";

	//Detailed screen processing
	//@Get the value received from the URL with PathVariable
	public String detail(@PathVariable long isbn, Model model) {

		model.addAttribute("msg", "Reference screen");
		Optional<BookData> data = bookService.findById(isbn);
		//When using Optional, the value is get()Get in
		model.addAttribute("form", data.get());

		return "detail";

	//Initialization process
	public void init() {

		BookData d1 = new BookData();
		d1.setAuthor("Natsume Soseki");

		BookData d2 = new BookData();
		d2.setAuthor("Jiro Ohno");
		d2.setTitle("Introduction to Spring");

		BookData d3 = new BookData();
		d3.setAuthor("Taro Tanaka");
		d3.setTitle("How the network works");

		BookData d4 = new BookData();
		d4.setAuthor("Yoshikawa amount");
		d4.setTitle("Mud bullet");

		BookData d5 = new BookData();
		d5.setAuthor("Natsume Soseki");

		BookData d6 = new BookData();
		d6.setAuthor("Test Toshiro");
		d6.setTitle("Serial murder case book");

		BookData d7 = new BookData();
		d7.setAuthor("Taro Serpent");
		d7.setTitle("Getting Started with Java");



<!DOCTYPE html>
<html xmlns:th="http://www.thymeleaf.org">
<meta charset="UTF-8">
<title>initial screen</title>
h1 {font-size:18pt; font-weight:bold; color:gray;}
body {font-size:13pt; font-weight:bold; color:gray; margin:5px 25px;}
tr {margin:5px;}
th {padding:5px;color:white; background:darkgray;}
td {padding:5px;color:black; background:#f0f0f0;}
	<h1 th:text="${msg}"></h1>
		<p th:text="${msg2}"></p>
		<!--Enter the value th:object="${formModel}"Pack in-->
		<!--th:Make the initial value enter in value-->
		<form method="post" th:action="@{/book}" th:object="${formModel}">
			<input type="text" name="genre" th:value="*{genre}"><p>
			<input type="text" name="author" th:value="*{author}"><p>
			<input type="text" name="title" th:value="*{title}"><p>
			<input type="submit" value="Search">
				<th>Author name</th>
				<th>Stock quantity</th>
			<tr th:each="obj:${books}" th:object="${obj}">
				<!--th:Link setting with href-->
				<td><a th:href="@{/book/detail/{isbn}(isbn=*{isbn})}" th:text="*{isbn}"></a></td>
				<td th:text="*{title}"></td>
				<td th:text="*{author}"></td>
				<td th:text="*{stock}"></td>
				<td th:text="*{genre}"></td>

Processing pattern 1

Enter "literature" in the genre and press the search button. When you move to the search result screen, the value entered on the previous page is retained and displayed on the screen. Click the ISBN link in the search results to move to the reference screen. image.png



Processing pattern 2

Enter "thick" for the author and press the search button. image.png



I created a simple app. We would appreciate it if you could let us know if you have any opinions such as "It is better to do this!"


[Introduction to Spring Boot 2 Programming](https://www.amazon.co.jp/Spring-Boot-2-%E3%83%97%E3%83%AD%E3%82%B0%E3%83%A9 % E3% 83% 9F% E3% 83% B3% E3% 82% B0% E5% 85% A5% E9% 96% 80-% E6% 8E% 8C% E7% 94% B0% E6% B4% A5% E8% 80% B6% E4% B9% 83-ebook / dp / B07KF4R1HT / ref = sr_1_3? __ mk_ja_JP =% E3% 82% AB% E3% 82% BF% E3% 82% AB% E3% 83% 8A & dchild = 1 & keywords = Spring + boot & qid = 1590664580 & sr = 8-3)

[Introduction to Spring](https://www.amazon.co.jp/Spring%E5%BE%B9%E5%BA%95%E5%85%A5%E9%96%80-Spring-Framework%E3% 81% AB% E3% 82% 88% E3% 82% 8BJava% E3% 82% A2% E3% 83% 97% E3% 83% AA% E3% 82% B1% E3% 83% BC% E3% 82% B7% E3% 83% A7% E3% 83% B3% E9% 96% 8B% E7% 99% BA-% E6% A0% AA% E5% BC% 8F% E4% BC% 9A% E7% A4% BENTT % E3% 83% 87% E3% 83% BC% E3% 82% BF-ebook / dp / B01IEWNLBU / ref = sr_1_2? __mk_ja_JP =% E3% 82% AB% E3% 82% BF% E3% 82% AB% E3% 83% 8A & dchild = 1 & keywords = Spring + boot & qid = 1590664580 & sr = 8-2)

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