JSPとセッションで簡単なログイン画面の実装

JSPとセッションで簡単なログイン画面の実装練習を行ったので復習として記載します。

完成イメージ
環境
ファイル構成
実装
おわりに

完成イメージ

環境

eclipse：2022-12 (4.26.0)
Tomcat9
Java17

ファイル構成

実装

package control;

import java.io.IOException;

import javax.servlet.RequestDispatcher;
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 javax.servlet.http.HttpSession;

/**
 * Servlet implementation class LoginServlet
 */
@WebServlet("/LoginServlet")
public class LoginServlet extends HttpServlet {
	private static final long serialVersionUID = 1L;
	/**
	 * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		
		request.setCharacterEncoding("UTF-8");
		String userId = request.getParameter("userId");
		
		HttpSession session = request.getSession();
		session.setAttribute("userId", userId);
		
		String url = "user-display.jsp";
		RequestDispatcher dispatcher = request.getRequestDispatcher(url);
		dispatcher.forward(request, response);
	}
}

package control;

import java.io.IOException;

import javax.servlet.RequestDispatcher;
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 javax.servlet.http.HttpSession;

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

	/**
	 * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		HttpSession session = request.getSession();
		
		//セッションの破棄
		session.invalidate();
		
		RequestDispatcher dispatcher = request.getRequestDispatcher("login.jsp");
		dispatcher.forward(request, response);
	}

}

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>ログイン画面</title>
</head>
<body>
<h2>ログイン</h2>
<form action="LoginServlet" method="post">
ユーザーID<input type="text" name="userId" required><br>
パスワード<input type="text" name="password" required><br>
<input type="submit" value="送信">
</form>

</body>
</html>

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<% String userId = (String) session.getAttribute("userId"); %>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>ユーザー画面</title>
</head>
<body>
<%=userId %>さん、こんにちは
<br><br>
<a href="LogoutServlet">ログアウト</a>
</body>
</html>