feature: #1299 Add Identity Map Pattern (#2094)

* #1299 IMPLEMENT IDENTITY MAP PATTERN. * #1299 Add docstrings, README, testCases and class diagram. * #1299 Update a comment string in DB implementation. * #1299 Fix code smells. * #1299 Fix code smells and add comments to App.java * #1299 Update constant name. * #1299 Remove java version dependency and update README.md. * #1299 Add lombok to PersonFinder.java. * #1299 Add dependency to maven-assembly-plugin. * #1299 Use java streams in PersonDbSimulatorImplementation.java. * #1299 Add print statements while returning the person object. * #1299 Update README.md. * #1299 Add puml file. * Update README.md
2026-05-17 04:59:21 +00:00 · 2022-11-10 06:55:44 +11:00
parent 3831a82b69
commit d2599a2904
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+/*
+ * 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.identitymap;
+
+import lombok.Getter;
+import lombok.Setter;
+import lombok.extern.slf4j.Slf4j;
+
+/**
+ * Any object of this class stores a DataBase and an Identity Map. When we try to look for a key we first check if
+ * it has been cached in the Identity Map and return it if it is indeed in the map.
+ * If that is not the case then go to the DataBase, get the record, store it in the
+ * Identity Map and then return the record. Now if we look for the record again we will find it in the table itself which
+ * will make lookup faster.
+ */
+@Slf4j
+@Getter
+@Setter
+public class PersonFinder {
+  private static final long serialVersionUID = 1L;
+  //  Access to the Identity Map
+  private IdentityMap identityMap = new IdentityMap();
+  private PersonDbSimulatorImplementation db = new PersonDbSimulatorImplementation();
+  /**
+   * get person corresponding to input ID.
+   *
+   * @param key : personNationalId to look for.
+   */
+  public Person getPerson(int key) {
+    // Try to find person in the identity map
+    Person person = this.identityMap.getPerson(key);
+    if (person != null) {
+      LOGGER.info("Person found in the Map");
+      return person;
+    } else {
+      // Try to find person in the database
+      person = this.db.find(key);
+      if (person != null) {
+        this.identityMap.addPerson(person);
+        LOGGER.info("Person found in DB.");
+        return person;
+      }
+      LOGGER.info("Person with this ID does not exist.");
+      return null;
+    }
+  }
+}