質問編集履歴

質問の内容およびServletのソースを修正いたしました。

2020/06/18 00:46

投稿

shogakusha

スコア12

test CHANGED Viewed

	@@ -1 +1 @@
1	- ~~一覧画面から詳細画面遷移時~~に~~、データが取得~~できず、nullとなってしまいます
1	+ DAOで設定した情報をServletに連携できず、値がnullとなってしまいます

test CHANGED Viewed

@@ -12,7 +12,7 @@
 一覧画面の各検索結果に「詳細」リンクがあり、押下したら詳細画面へ遷移し、該当文書のタイトル、作者、内容が表示されるように実装したいです。
-その際に、IDをキーに、文書の内容等が表示されるようにしたいのですが、IDの情報を取得することができず、タイトル、作者、内容がすべてnullとなってしまいます。
+DAOではIDの情報を取得するができ、タイトル、作者、内容の値を取得できているのですが、Servletではタイトル、作者、内容の値がnullとなってしまい、理由が分かりません。
 初学者のため、質問に難有りかと思いますが、ご容赦ください。
@@ -206,412 +206,414 @@
 		BookDto book = new BookDto(id, bookName, detail, author);
+		String idAsString = request.getParameter("id");
+		id = Integer.parseInt(idAsString);
+		DBManager db = new DBManager();
+		try {
+			BookDao bookDao = new BookDao(db);
+			ArrayList<BookDto> list = bookDao.find(id);
+			request.setCharacterEncoding("UTF8");
+			request.setAttribute("list", list);
+			if (list != null) {
+				bookName = book.getBooktitle();
+				detail = book.getBooktext();
+				author = book.getAuthor();
+				request.setAttribute("booktitle", bookName);
+				request.setAttribute("text", detail);
+				request.setAttribute("author", author);
+				RequestDispatcher dispatcher = request.getRequestDispatcher("/detail.jsp");
+				dispatcher.forward(request, response);
+			}
+		} catch (Exception e) {
+			e.printStackTrace();
+		}
+	}
+}
+```
+```BookDao.java
+package dao;
+import java.sql.Connection;
+import java.sql.PreparedStatement;
+import java.sql.ResultSet;
+import java.util.ArrayList;
+import dba.DBManager;
+import dto.BookDto;
+import dto.BookSearchDto;
+public class BookDao {
+	Connection conn = null;
+	PreparedStatement pStmt = null;
+	ResultSet rs = null;
+	private DBManager db;
+	public BookDao(DBManager db) {
+		this.db = db;
+	}
+	public ArrayList<BookSearchDto> findAll() throws Exception {
+		ArrayList<BookSearchDto> bookList = new ArrayList<BookSearchDto>();
+		String sql = "SELECT ID, BOOKTITLE, BOOKTEXT, AUTHOR, UPDATETIME, UPDATEUSER, INSERTTIME, INSERTUSER FROM T_BOOK";
+		Connection conn = db.getConnection();
+		PreparedStatement pStmt = conn.prepareStatement(sql);
+		ResultSet rs = pStmt.executeQuery();
+		while (rs.next()) {
+			int id = rs.getInt("ID");
+			String booktitle = rs.getString("BOOKTITLE");
+			String author = rs.getString("AUTHOR");
+			BookSearchDto bookSearch = new BookSearchDto(id, booktitle, author);
+			bookList.add(bookSearch);
+		}
+		return bookList;
+	}
+	public ArrayList<BookSearchDto> find(String bookName) throws Exception {
+		ArrayList<BookSearchDto> bookList = new ArrayList<BookSearchDto>();
+		String sql = "SELECT ID, BOOKTITLE, AUTHOR FROM T_BOOK WHERE BOOKTITLE LIKE ?";
+		Connection conn = db.getConnection();
+		PreparedStatement pStmt = conn.prepareStatement(sql);
+		pStmt.setString(1, bookName + "%");
+		ResultSet rs = pStmt.executeQuery();
+		while (rs.next()) {
+			int id = rs.getInt("ID");
+			bookName = rs.getString("BOOKTITLE");
+			String author = rs.getString("AUTHOR");
+			BookSearchDto bookSearch = new BookSearchDto(id, bookName, author);
+			bookList.add(bookSearch);
+		}
+		return bookList;
+	}
+	public ArrayList<BookDto> find(int id) throws Exception {
+		String booktitle = null;
+		String text = null;
+		String author = null;
+		BookDto book = new BookDto(id, booktitle, text, author);
+		ArrayList<BookDto> list = new ArrayList<BookDto>();
+		String sql = "SELECT BOOKTITLE, BOOKTEXT, AUTHOR FROM T_BOOK WHERE ID = ?";
+		Connection conn = db.getConnection();
+		PreparedStatement pStmt = conn.prepareStatement(sql);
 		id = book.getId();
+		pStmt.setInt(1, id);
-		DBManager db = new DBManager();
+		ResultSet rs = pStmt.executeQuery();
-		try {
+		while (rs.next()) {
-			BookDao bookDao = new BookDao(db);
+			id = rs.getInt("ID");
-			ArrayList<BookDto> list = bookDao.find(id);
+			booktitle = rs.getString("BOOKTITLE");
+			text = rs.getString("BOOKTEXT");
-			request.setCharacterEncoding("UTF8");
+			author = rs.getString("AUTHOR");
-			request.setAttribute("list", list);
-			if (list != null) {
-				bookName = book.getBooktitle();
-				detail = book.getBooktext();
-				author = book.getAuthor();
-				request.setAttribute("booktitle", bookName);
-				request.setAttribute("text", detail);
-				request.setAttribute("author", author);
+			book = new BookDto(id, booktitle, text, author);
-				RequestDispatcher dispatcher = request.getRequestDispatcher("/detail.jsp");
-				dispatcher.forward(request, response);
-			}
-		} catch (Exception e) {
-			e.printStackTrace();
+			list.add(book);
 		}
+		return list;
 	}
+	public boolean regist(BookDto book) throws Exception {
+		boolean judge = false;
+		String sql = "INSERT INTO T_BOOK(BOOKTITLE, BOOKTEXT, AUTHOR) VALUES(?, ?, ?)";
+		String booktitle = book.getBooktitle();
+		String booktext = book.getBooktext();
+		String author = book.getAuthor();
+		Connection conn = db.getConnection();
+		PreparedStatement pStmt = conn.prepareStatement(sql);
+		pStmt.setString(1, booktitle);
+		pStmt.setString(2, booktext);
+		pStmt.setString(3, author);
+		int count = pStmt.executeUpdate();
+		if (count == 1) {
+			judge = true;
+		}
+		return judge;
+	}
+	public boolean update(BookDto book) throws Exception {
+		boolean judge = false;
+		String sql = "UODATE T_BOOK SET BOOKTITLE = ?, BOOKTEXT = ?, AUTHOR = ?";
+		String booktitle = book.getBooktitle();
+		String booktext = book.getBooktext();
+		String author = book.getAuthor();
+		Connection conn = db.getConnection();
+		PreparedStatement pStmt = conn.prepareStatement(sql);
+		pStmt.setString(1, booktitle);
+		pStmt.setString(2, booktext);
+		pStmt.setString(3, author);
+		int count = pStmt.executeUpdate();
+		if (count == 1) {
+			judge = true;
+		}
+		return judge;
+	}
 }
 ```
-```BookDao.java
-package dao;
-import java.sql.Connection;
-import java.sql.PreparedStatement;
-import java.sql.ResultSet;
-import java.util.ArrayList;
-import dba.DBManager;
-import dto.BookDto;
-import dto.BookSearchDto;
-public class BookDao {
-	Connection conn = null;
-	PreparedStatement pStmt = null;
-	ResultSet rs = null;
-	private DBManager db;
-	public BookDao(DBManager db) {
-		this.db = db;
-	}
-	public ArrayList<BookSearchDto> findAll() throws Exception {
-		ArrayList<BookSearchDto> bookList = new ArrayList<BookSearchDto>();
-		String sql = "SELECT ID, BOOKTITLE, BOOKTEXT, AUTHOR, UPDATETIME, UPDATEUSER, INSERTTIME, INSERTUSER FROM T_BOOK";
-		Connection conn = db.getConnection();
-		PreparedStatement pStmt = conn.prepareStatement(sql);
-		ResultSet rs = pStmt.executeQuery();
-		while (rs.next()) {
-			int id = rs.getInt("ID");
-			String booktitle = rs.getString("BOOKTITLE");
-			String author = rs.getString("AUTHOR");
-			BookSearchDto bookSearch = new BookSearchDto(id, booktitle, author);
-			bookList.add(bookSearch);
-		}
-		return bookList;
-	}
-	public ArrayList<BookSearchDto> find(String bookName) throws Exception {
-		ArrayList<BookSearchDto> bookList = new ArrayList<BookSearchDto>();
-		String sql = "SELECT ID, BOOKTITLE, AUTHOR FROM T_BOOK WHERE BOOKTITLE LIKE ?";
-		Connection conn = db.getConnection();
-		PreparedStatement pStmt = conn.prepareStatement(sql);
-		pStmt.setString(1, bookName + "%");
-		ResultSet rs = pStmt.executeQuery();
-		while (rs.next()) {
-			int id = rs.getInt("ID");
-			bookName = rs.getString("BOOKTITLE");
-			String author = rs.getString("AUTHOR");
-			BookSearchDto bookSearch = new BookSearchDto(id, bookName, author);
-			bookList.add(bookSearch);
-		}
-		return bookList;
-	}
-	public ArrayList<BookDto> find(int id) throws Exception {
-		String booktitle = null;
-		String text = null;
+```detail.jsp
+<%@ page language="java" contentType="text/html; charset=UTF-8"
+	pageEncoding="UTF-8" import="java.io.*,java.util.*,java.text.*,dto.*"%>
+<!DOCTYPE html">
+<html>
+<head>
+<meta charset="UTF-8">
+<title>詳細画面</title>
+</head>
+<body>
+	<%
+		//　リストデータをリクエストから取得
+		int id = 0;
+		String bookName = null;
 		String author = null;
-		BookDto book = new BookDto(id, booktitle, text, author);
-		ArrayList<BookDto> list = new ArrayList<BookDto>();
-		String sql = "SELECT BOOKTITLE, BOOKTEXT, AUTHOR FROM T_BOOK WHERE ID = ?";
-		Connection conn = db.getConnection();
-		PreparedStatement pStmt = conn.prepareStatement(sql);
-		id = book.getId();
-		pStmt.setInt(1, id);
-		ResultSet rs = pStmt.executeQuery();
-		while (rs.next()) {
-			id = rs.getInt("ID");
-			booktitle = rs.getString("BOOKTITLE");
-			text = rs.getString("BOOKTEXT");
-			author = rs.getString("AUTHOR");
-			book = new BookDto(id, booktitle, text, author);
-			list.add(book);
-		}
-		return list;
-	}
-	public boolean regist(BookDto book) throws Exception {
-		boolean judge = false;
-		String sql = "INSERT INTO T_BOOK(BOOKTITLE, BOOKTEXT, AUTHOR) VALUES(?, ?, ?)";
-		String booktitle = book.getBooktitle();
-		String booktext = book.getBooktext();
-		String author = book.getAuthor();
-		Connection conn = db.getConnection();
-		PreparedStatement pStmt = conn.prepareStatement(sql);
-		pStmt.setString(1, booktitle);
-		pStmt.setString(2, booktext);
-		pStmt.setString(3, author);
-		int count = pStmt.executeUpdate();
-		if (count == 1) {
-			judge = true;
-		}
-		return judge;
-	}
-	public boolean update(BookDto book) throws Exception {
-		boolean judge = false;
-		String sql = "UODATE T_BOOK SET BOOKTITLE = ?, BOOKTEXT = ?, AUTHOR = ?";
-		String booktitle = book.getBooktitle();
-		String booktext = book.getBooktext();
-		String author = book.getAuthor();
-		Connection conn = db.getConnection();
-		PreparedStatement pStmt = conn.prepareStatement(sql);
-		pStmt.setString(1, booktitle);
-		pStmt.setString(2, booktext);
-		pStmt.setString(3, author);
-		int count = pStmt.executeUpdate();
-		if (count == 1) {
-			judge = true;
-		}
-		return judge;
-	}
-}
+		String detail = null;
+		BookDto book = new BookDto(id, bookName, detail, author);
+		request.getAttribute("book");
+		bookName = book.getBooktitle();
+		author = book.getAuthor();
+		detail = book.getBooktext();
+	%>
+	<h2><%=bookName%></h2>
+	<h3>
+		作者:<%=author%></h3>
+	<%=detail%>
+	<br>
+	<button onclick="history.back()">戻る</button>
+</body>
+</html>
 ```
-```detail.jsp
-<%@ page language="java" contentType="text/html; charset=UTF-8"
-	pageEncoding="UTF-8" import="java.io.*,java.util.*,java.text.*,dto.*"%>
-<!DOCTYPE html">
-<html>
-<head>
-<meta charset="UTF-8">
-<title>詳細画面</title>
-</head>
-<body>
-	<%
-		//　リストデータをリクエストから取得
-		int id = 0;
-		String bookName = null;
-		String author = null;
-		String detail = null;
-		BookDto book = new BookDto(id, bookName, detail, author);
-		request.getAttribute("book");
-		bookName = book.getBooktitle();
-		author = book.getAuthor();
-		detail = book.getBooktext();
-	%>
-	<h2><%=bookName%></h2>
-	<h3>
-		作者:<%=author%></h3>
-	<%=detail%>
-	<br>
-	<button onclick="history.back()">戻る</button>
-</body>
-</html>
-```