jspでテーブル検索

Question

前提・実現したいこと

jspでテーブルの検索結果が0件だった場合、「該当する書籍は存在しません」
と表示したい。

該当のソースコード

package jp.co.sss.book.bean;

import java.sql.Date;

public class Book {

    /** 書籍ID  */
    private int bookId;

    /** 書籍名 */
    private String bookName;

    /** 著者 */
    private String author;

    /** 発行日 */
    private Date publicationDate;

    /** 在庫 */
    private int stock;

    /** ジャンルID */
    private Genre genre;

    /**
     * ブックIDを取得
     *
     * @return ブックID
     */
    public int getBookId() {
        return bookId;
    }

    /**
     * ブックIDを保存
     *
     * @param bookId
     *            ブックID
     */
    public void setBookId(int bookId) {
        this.bookId = bookId;
    }

    public String getBookName() {
        return bookName;
    }

    public void setBookName(String bookName) {
        this.bookName = bookName;
    }

    public void setAuthor(String author) {
        this.author = author;
    }

    public String getAuthor() {
        return author;
    }

    public Date getPublicationDate() {
        return publicationDate;
    }

    public void setPublicationDate(Date publicationDate) {
        this.publicationDate = publicationDate;
    }

    public int getStock() {
        return stock;
    }

    public void setStock(int stock) {
        this.stock = stock;
    }

	public Genre getGenre() {
		return genre;
	}

	public void setGenre(Genre genre) {
		this.genre = genre;
	}
}

package jp.co.sss.book.dao;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;

import jp.co.sss.book.bean.Book;
import jp.co.sss.book.bean.Genre;

public class BookSerchDao {

	/*
	 * 書名検索
	 */
    public static List<Book> findByBookName(String bookName){

        Connection con = null;
        PreparedStatement ps = null;
        ResultSet rs = null;

        List<Book> bookSerch = new ArrayList<Book>();

        try {
            con = DBManager.getConnection();

            String sql = "SELECT * FROM book b INNER JOIN genre g ON b.genre_id = 
            g.genre_id WHERE b.book_name LIKE ?";

            	ps = con.prepareStatement(sql);
	            ps.setString(1, "%" + bookName + "%");
	            rs = ps.executeQuery();

	            while(rs.next()) {
	                Book book = new Book();
	                book.setBookId(rs.getInt("book_id"));
	                book.setBookName(rs.getString("book_name"));
	                book.setAuthor(rs.getString("author"));
	                book.setPublicationDate(rs.getDate("publication_date"));
	                book.setStock(rs.getInt("stock"));

	                Genre genre = new Genre();
	                genre.setGenreId(rs.getInt("genre_id"));
	                genre.setGenreName(rs.getString("genre_name"));

	                book.setGenre(genre);
	                bookSerch.add(book);
	            }

        }catch (SQLException e) {
            e.printStackTrace();
        } finally {
            DBManager.close(rs);
            DBManager.close(ps);
            DBManager.close(con);
        }
        return bookSerch;
    }

}

package jp.co.sss.book.servlet;

import java.io.IOException;
import java.util.List;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import jp.co.sss.book.bean.Book;
import jp.co.sss.book.dao.BookSerchDao;


@WebServlet("/BookSerch")
public class BookSerch extends HttpServlet {
    private static final long serialVersionUID = 1L;

    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {


    	String bookName = (String)request.getParameter("bookName");
        List<Book> bookSerch = BookSerchDao.findByBookName(bookName);

        request.setAttribute("bookSerch", bookSerch);
        request.getRequestDispatcher("/jsp/select/book_serch.jsp").forward(request, response);
    }
}

<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%>
<%@taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%>
<%@ page import="jp.co.sss.book.bean.Book" %>
<!DOCTYPE html>
<html lang="ja">
    <head>
        <meta charset="UTF-8">
        <link href="<%=request.getContextPath()%>/css/style.css" rel="stylesheet" type="text/css" />
        <title>書籍一覧画面</title>
    </head>

    <body>
		<%@include file="/jsp/common/header.jsp"%>
		<a href="<%=request.getContextPath()%>/logout">ログアウト</a>
		<div id="main">
			<table>
	            <tr>
	                <th>書籍ID</th>
	                <th>書籍名</th>
	                <th>筆者</th>
	                <th>発行日</th>
	                <th>在庫</th>
	                <th>ジャンル</th>
	            </tr>

			 <c:forEach var="book" items="${bookSerch}">
			<tr>
				<td><c:out value="${book.bookId}" /></td>
				<td><c:out value="${book.bookName}" /></td>
				<td><c:out value="${book.author}" /></td>
				<td><c:out value="${book.publicationDate}" /></td>
				<td><c:out value="${book.stock}" /></td>
				<td><c:out value="${book.genre.genreName}" /></td>

			</tr>
			</c:forEach>
	         </table>
	         <a href="<%=request.getContextPath()%>/jsp/select/list.jsp">一覧表示に戻る</a>
		</div>
        <%@include file="/jsp/common/footer.jsp"%>
    </body>
</html>

よろしくお願いします。

Comments

[javahack]

質問は何でしょうか。

[kk12345]

isEmptyで判定できるところまではいけましたが、そこからどうやってjspでメッセージを表示させたらいいかわかりません

Answer 1

BookSerchに
if (bookSerch.isEmpty()){
request.setAttribute("errorMsg", "該当する書籍は存在しません");
request.getRequestDispatcher("/jsp/select/book_serch.jsp").forward(request,
response);
return;
}
と記述しjspで取得すれば表示することができました。