server-session/src/main/java/com/iluwatar/sessionserver/App.java - master - githubmirror/java-design-patterns

server-session/src/main/java/com/iluwatar/sessionserver/App.java
116 строк5 KB
Ilkka Seppälä
deps: Refactor dependencies (#3224)
29 мар 2025, 20:34
29 мар 2025, 20:340ca162a
/*
 * This project is licensed under the MIT license. Module model-view-viewmodel is using ZK framework licensed under LGPL (see lgpl-3.0.txt).
 *
 * The MIT License
 * Copyright © 2014-2022 Ilkka Seppälä
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */
package com.iluwatar.sessionserver;

import com.sun.net.httpserver.HttpServer;
import java.io.IOException;
import java.net.InetSocketAddress;
import java.time.Instant;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import lombok.extern.slf4j.Slf4j;

/**
 * The server session pattern is a behavioral design pattern concerned with assigning the
 * responsibility of storing session data on the server side. Within the context of stateless
 * protocols like HTTP all requests are isolated events independent of previous requests. In order
 * to create sessions during user-access for a particular web application various methods can be
 * used, such as cookies. Cookies are a small piece of data that can be sent between client and
 * server on every request and response so that the server can "remember" the previous requests. In
 * general cookies can either store the session data or the cookie can store a session identifier
 * and be used to access appropriate data from a persistent storage. In the latter case the session
 * data is stored on the server-side and appropriate data is identified by the cookie sent from a
 * client's request. This project demonstrates the latter case. In the following example the ({@link
 * App}) class starts a server and assigns ({@link LoginHandler}) class to handle login request.
 * When a user logs in a session identifier is created and stored for future requests in a list.
 * When a user logs out the session identifier is deleted from the list along with the appropriate
 * user session data, which is handle by the ({@link LogoutHandler}) class.
 */
@Slf4j
public class App {

  // Map to store session data (simulated using a HashMap)
  private static Map<String, Integer> sessions = new HashMap<>();
  private static Map<String, Instant> sessionCreationTimes = new HashMap<>();
  private static final long SESSION_EXPIRATION_TIME = 10000;

  /**
   * Main entry point.
   *
   * @param args arguments
   * @throws IOException ex
   */
  public static void main(String[] args) throws IOException {
    // Create HTTP server listening on port 8000
    HttpServer server = HttpServer.create(new InetSocketAddress(8080), 0);

    // Set up session management endpoints
    server.createContext("/login", new LoginHandler(sessions, sessionCreationTimes));
    server.createContext("/logout", new LogoutHandler(sessions, sessionCreationTimes));

    // Start the server
    server.start();

    // Start background task to check for expired sessions
    sessionExpirationTask();

    LOGGER.info("Server started. Listening on port 8080...");
  }

  private static void sessionExpirationTask() {
    new Thread(
            () -> {
              while (true) {
                try {
                  LOGGER.info("Session expiration checker started...");
                  Thread.sleep(SESSION_EXPIRATION_TIME); // Sleep for expiration time
                  Instant currentTime = Instant.now();
                  synchronized (sessions) {
                    synchronized (sessionCreationTimes) {
                      Iterator<Map.Entry<String, Instant>> iterator =
                          sessionCreationTimes.entrySet().iterator();
                      while (iterator.hasNext()) {
                        Map.Entry<String, Instant> entry = iterator.next();
                        if (entry
                            .getValue()
                            .plusMillis(SESSION_EXPIRATION_TIME)
                            .isBefore(currentTime)) {
                          sessions.remove(entry.getKey());
                          iterator.remove();
                        }
                      }
                    }
                  }
                  LOGGER.info("Session expiration checker finished!");
                } catch (InterruptedException e) {
                  LOGGER.error("An error occurred: ", e);
                  Thread.currentThread().interrupt();
                }
              }
            })
        .start();
  }
}