basic implementation ++

basic implementation ++

data-mapper/src/main/java/com/iluwatar/datamapper/App.java

@@ -0,0 +1,105 @@
+/**
+ * The MIT License Copyright (c) 2014 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.datamapper;
+
+import java.util.Optional;
+import java.util.UUID;
+
+import org.apache.log4j.Logger;
+
+/**
+ * 
+ * The Data Mapper (DM) is a layer of software that separates the in-memory objects from the
+ * database. Its responsibility is to transfer data between the two and also to isolate them from
+ * each other. With Data Mapper the in-memory objects needn't know even that there's a database
+ * present; they need no SQL interface code, and certainly no knowledge of the database schema. (The
+ * database schema is always ignorant of the objects that use it.) Since it's a form of Mapper ,
+ * Data Mapper itself is even unknown to the domain layer.
+ * <p>
+ * The below example demonstrates basic CRUD operations: select, add, update, and delete.
+ * 
+ */
+public final class App {
+
+  private static Logger log = Logger.getLogger(App.class);
+
+
+  private static final String DB_TYPE_ORACLE = "Oracle";
+  private static final String DB_TYPE_MYSQL = "MySQL";
+
+
+  /**
+   * Program entry point.
+   * 
+   * @param args command line args.
+   */
+  public static final void main(final String... args) {
+
+    if (log.isInfoEnabled() & args.length > 0) {
+      log.debug("App.main(), db type: " + args[0]);
+    }
+
+    StudentDataMapper mapper = null;
+
+    /* Check the desired db type from runtime arguments */
+    if (args.length == 0) {
+
+      /* Create default data mapper for mysql */
+      mapper = new StudentMySQLDataMapper();
+
+    } else if (args.length > 0 && DB_TYPE_ORACLE.equalsIgnoreCase(args[0])) {
+
+      /* Create new data mapper for mysql */
+      mapper = new StudentMySQLDataMapper();
+
+    } else if (args.length > 0 && DB_TYPE_MYSQL.equalsIgnoreCase(args[0])) {
+
+      /* Create new data mapper for oracle */
+      mapper = new StudentMySQLDataMapper();
+    } else {
+
+      /* Don't couple any Data Mapper to java.sql.SQLException */
+      throw new DataMapperException("Following data source(" + args[0] + ") is not supported");
+    }
+
+    /* Create new student */
+    Student student = new Student(UUID.randomUUID(), 1, "Adam", 'A');
+
+    /* Add student in respectibe db */
+    mapper.insert(student);
+
+    /* Find this student */
+    final Optional<Student> studentToBeFound = mapper.find(student.getGuId());
+
+    if (log.isDebugEnabled()) {
+      log.debug("App.main(), db find returned : " + studentToBeFound);
+    }
+
+    /* Update existing student object */
+    student = new Student(student.getGuId(), 1, "AdamUpdated", 'A');
+
+    /* Update student in respectibe db */
+    mapper.update(student);
+
+    /* Delete student in db */
+    mapper.delete(student);
+  }
+
+  private App() {}
+}