basic implementation ++

basic implementation ++

data-mapper/index.md

@@ -0,0 +1,26 @@
+---
+layout: pattern
+title: Data Mapper
+folder: data-mapper
+permalink: /patterns/dm/
+categories: Persistence Tier
+tags:
+ - Java
+ - Difficulty-Beginner
+---
+
+## Intent
+Object provides an abstract interface to some type of database or
+other persistence mechanism.
+
+![alt text](./etc/dm.png "Data Mapper")
+
+## Applicability
+Use the Data Mapper in any of the following situations
+
+* when you want to consolidate how the data layer is accessed
+* when you want to avoid writing multiple data retrieval/persistence layers
+
+## Credits
+
+* [Data Mapper](http://richard.jp.leguen.ca/tutoring/soen343-f2010/tutorials/implementing-data-mapper/)

data-mapper/pom.xml

@@ -0,0 +1,93 @@
+<?xml version="1.0"?>
+<!--
+
+    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.
+
+-->
+<project
+  xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"
+  xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
+  <modelVersion>4.0.0</modelVersion>
+  <parent>
+    <groupId>com.iluwatar</groupId>
+    <artifactId>java-design-patterns</artifactId>
+    <version>1.11.0-SNAPSHOT</version>
+  </parent>
+  <artifactId>data-mapper</artifactId>
+
+  <dependencies>
+    <dependency>
+      <groupId>junit</groupId>
+      <artifactId>junit</artifactId>
+      <scope>test</scope>
+    </dependency>
+    <dependency>
+      <groupId>log4j</groupId>
+      <artifactId>log4j</artifactId>
+    </dependency>
+  </dependencies>
+
+  <build>
+
+    <!-- 
+    log4j.xml file will be copied both in ${project.build.outputDirectory} 
+    and ${project.build.directory}. Thanks to Sean Patrick Floyd 
+    (http://stackoverflow.com/questions/5637532/maven-how-to-place-resource-file-together-with-jar) 
+    -->
+      
+    <resources>
+      <resource> <!-- regular processing for every resource file -->
+        <directory>src/main/resources</directory>
+      </resource>
+      <resource> <!-- processing with a different output directory for log4j.xml -->
+        <directory>src/main/resources</directory>
+        <includes>
+          <include>log4j.xml</include>
+        </includes>
+        <targetPath>..</targetPath> <!-- relative to target/classes i.e. ${project.build.directory} -->
+      </resource>
+    </resources>
+
+    <plugins>
+
+      <!-- 
+      This will exclude log4j.xml file from generated JAR 
+      -->
+      <plugin>
+        <groupId>org.apache.maven.plugins</groupId>
+        <artifactId>maven-jar-plugin</artifactId>
+        <version>2.6</version>
+        <configuration>
+          <excludes>
+            <exclude>log4j.xml</exclude>
+          </excludes>
+          <archive>
+            <manifest>
+              <addClasspath>true</addClasspath>
+            </manifest>
+          </archive>
+        </configuration>
+      </plugin>
+
+    </plugins>
+  </build>
+</project>

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() {}
+}

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

@@ -0,0 +1,79 @@
+/**
+ * The MIT License Copyright (c) 2016 Amit Dixit
+ *
+ * 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;
+
+/**
+ * 
+ * @author amit.dixit
+ *
+ */
+public final class DataMapperException extends RuntimeException {
+
+  private static final long serialVersionUID = 1L;
+
+  /**
+   * Constructs a new runtime exception with {@code null} as its detail message. The cause is not
+   * initialized, and may subsequently be initialized by a call to {@link #initCause}.
+   */
+  public DataMapperException() {
+    super();
+  }
+
+
+  /**
+   * Constructs a new runtime exception with the specified detail message. The cause is not
+   * initialized, and may subsequently be initialized by a call to {@link #initCause}.
+   *
+   * @param message the detail message. The detail message is saved for later retrieval by the
+   *        {@link #getMessage()} method.
+   */
+  public DataMapperException(final String message) {
+    super(message);
+  }
+
+  /**
+   * Constructs a new runtime exception with the specified detail message and cause.
+   * <p>
+   * Note that the detail message associated with {@code cause} is <i>not</i> automatically
+   * incorporated in this runtime exception's detail message.
+   *
+   * @param message the detail message (which is saved for later retrieval by the
+   *        {@link #getMessage()} method).
+   * @param cause the cause (which is saved for later retrieval by the {@link #getCause()} method).
+   *        (A <tt>null</tt> value is permitted, and indicates that the cause is nonexistent or
+   *        unknown.)
+   */
+  public DataMapperException(final String message, final Throwable cause) {
+    super(message, cause);
+  }
+
+  /**
+   * Constructs a new runtime exception with the specified cause and a detail message of
+   * <tt>(cause==null ? null : cause.toString())</tt> (which typically contains the class and detail
+   * message of <tt>cause</tt>). This constructor is useful for runtime exceptions that are little
+   * more than wrappers for other throwables.
+   *
+   * @param cause the cause (which is saved for later retrieval by the {@link #getCause()} method).
+   *        (A <tt>null</tt> value is permitted, and indicates that the cause is nonexistent or
+   *        unknown.)
+   */
+  public DataMapperException(final Throwable cause) {
+    super(cause);
+  }
+}

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

@@ -0,0 +1,83 @@
+/**
+ * The MIT License Copyright (c) 2016 Amit Dixit
+ *
+ * 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.io.Serializable;
+import java.util.UUID;
+
+public final class Student implements Serializable {
+
+  private static final long serialVersionUID = 1L;
+
+  private UUID guid;
+  private int studentID;
+  private String name;
+  private char grade;
+
+  public Student() {
+    this.guid = UUID.randomUUID();
+  }
+
+  public Student(final UUID guid, final int studentID, final String name, final char grade) {
+    super();
+
+    this.guid = guid;
+    this.studentID = studentID;
+    this.name = name;
+    this.grade = grade;
+  }
+
+
+  public Student(final UUID guid) {
+    this.guid = guid;
+  }
+
+  public final int getStudentId() {
+    return studentID;
+  }
+
+  public final void setStudentId(final int studentID) {
+    this.studentID = studentID;
+  }
+
+  public final String getName() {
+    return name;
+  }
+
+  public final void setName(final String name) {
+    this.name = name;
+  }
+
+  public final char getGrade() {
+    return grade;
+  }
+
+  public final void setGrade(final char grade) {
+    this.grade = grade;
+  }
+
+  public final UUID getGuId() {
+    return guid;
+  }
+
+  @Override
+  public final String toString() {
+    return "Student [guid=" + guid + ", studentID=" + studentID + ", name=" + name + ", grade=" + grade + "]";
+  }
+}

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

@@ -0,0 +1,33 @@
+/**
+ * The MIT License Copyright (c) 2016 Amit Dixit
+ *
+ * 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;
+
+public interface StudentDataMapper {
+
+  public Optional<Student> find(final UUID uniqueID) throws DataMapperException;
+
+  public void insert(final Student student) throws DataMapperException;
+
+  public void update(final Student student) throws DataMapperException;
+
+  public void delete(final Student student) throws DataMapperException;
+}

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

@@ -0,0 +1,160 @@
+/**
+ * The MIT License Copyright (c) 2016 Amit Dixit
+ *
+ * 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.sql.Connection;
+import java.sql.DriverManager;
+import java.sql.PreparedStatement;
+import java.sql.ResultSet;
+import java.sql.SQLException;
+import java.util.Optional;
+import java.util.UUID;
+
+public final class StudentMySQLDataMapper implements StudentDataMapper {
+
+  @Override
+  public final Optional<Student> find(final UUID uniqueID) throws DataMapperException {
+
+    try {
+      /* OracleDriver class cant be initilized directly */
+      Class.forName("oracle.jdbc.driver.OracleDriver");
+
+      /* Create new connection */
+      final Connection connection = DriverManager.getConnection("jdbc:mysql://localhost/MySQL", "username", "password");
+
+      /* Create new Oracle compliant sql statement */
+      final String statement = "SELECT `guid`, `grade`, `studentID`, `name` FROM `students` where `guid`=?";
+      final PreparedStatement dbStatement = connection.prepareStatement(statement);
+
+      /* Set unique id in sql statement */
+      dbStatement.setString(1, uniqueID.toString());
+
+      /* Execute the sql query */
+      final ResultSet rs = dbStatement.executeQuery();
+
+      while (rs.next()) {
+
+        /* Create new student */
+        final Student student = new Student(UUID.fromString(rs.getString("guid")));
+
+        /* Set all values from database in java object */
+        student.setName(rs.getString("name"));
+        student.setGrade(rs.getString("grade").charAt(0));
+        student.setStudentId(rs.getInt("studentID"));
+
+        return Optional.of(student);
+      }
+    } catch (final SQLException | ClassNotFoundException e) {
+
+      /* Don't couple any Data Mapper to java.sql.SQLException */
+      throw new DataMapperException("Error occured reading Students from MySQL data source.", e);
+    }
+
+    /* Return empty value */
+    return Optional.empty();
+  }
+
+  @Override
+  public final void update(final Student student) throws DataMapperException {
+    try {
+
+      /* OracleDriver class cant be initilized directly */
+      Class.forName("oracle.jdbc.driver.OracleDriver");
+
+      /* Create new connection */
+      final Connection connection = DriverManager.getConnection("jdbc:mysql://localhost/MySQL", "username", "password");
+
+      /* Create new Oracle compliant sql statement */
+      final String statement = "UPDATE `students` SET `grade`=?, `studentID`=?, `name`=? where `guid`=?";
+
+      final PreparedStatement dbStatement = connection.prepareStatement(statement);
+
+      /* Set java object values in sql statement */
+      dbStatement.setString(1, Character.toString(student.getGrade()));
+      dbStatement.setInt(2, student.getStudentId());
+      dbStatement.setString(3, student.getName());
+      dbStatement.setString(4, student.getGuId().toString());
+
+      /* Execute the sql query */
+      dbStatement.executeUpdate();
+
+    } catch (final SQLException | ClassNotFoundException e) {
+
+      /* Don't couple any Data Mapper to java.sql.SQLException */
+      throw new DataMapperException("Error occured reading Students from MySQL data source.", e);
+    }
+  }
+
+  @Override
+  public final void insert(final Student student) throws DataMapperException {
+    try {
+
+      /* OracleDriver class cant be initilized directly */
+      Class.forName("oracle.jdbc.driver.OracleDriver");
+
+      /* Create new connection */
+      final Connection connection = DriverManager.getConnection("jdbc:mysql://localhost/MySQL", "username", "password");
+
+      /* Create new Oracle compliant sql statement */
+      final String statement = "INSERT INTO `students` (`grade`, `studentID`, `name`, `guid`) VALUES (?, ?, ?, ?)";
+      final PreparedStatement dbStatement = connection.prepareStatement(statement);
+
+      /* Set java object values in sql statement */
+      dbStatement.setString(1, Character.toString(student.getGrade()));
+      dbStatement.setInt(2, student.getStudentId());
+      dbStatement.setString(3, student.getName());
+      dbStatement.setString(4, student.getGuId().toString());
+
+      /* Execute the sql query */
+      dbStatement.executeUpdate();
+
+    } catch (final SQLException | ClassNotFoundException e) {
+
+      /* Don't couple any Data Mapper to java.sql.SQLException */
+      throw new DataMapperException("Error occured reading Students from MySQL data source.", e);
+    }
+  }
+
+  @Override
+  public final void delete(final Student student) throws DataMapperException {
+    try {
+
+      /* OracleDriver class cant be initilized directly */
+      Class.forName("oracle.jdbc.driver.OracleDriver");
+
+      /* Create new connection */
+      final Connection connection = DriverManager.getConnection("jdbc:mysql://localhost/MySQL", "username", "password");
+
+      /* Create new Oracle compliant sql statement */
+      final String statement = "DELETE FROM `students` where `guid`=?";
+      final PreparedStatement dbStatement = connection.prepareStatement(statement);
+
+      /* Set java object values in sql statement */
+      dbStatement.setString(1, student.getGuId().toString());
+
+      /* Execute the sql query */
+      dbStatement.executeUpdate();
+
+    } catch (final SQLException | ClassNotFoundException e) {
+
+      /* Don't couple any Data Mapper to java.sql.SQLException */
+      throw new DataMapperException("Error occured reading Students from MySQL data source.", e);
+    }
+  }
+}

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

@@ -0,0 +1,160 @@
+/**
+ * The MIT License Copyright (c) 2016 Amit Dixit
+ *
+ * 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.sql.Connection;
+import java.sql.DriverManager;
+import java.sql.PreparedStatement;
+import java.sql.ResultSet;
+import java.sql.SQLException;
+import java.util.Optional;
+import java.util.UUID;
+
+public final class StudentOracleDataMapper implements StudentDataMapper {
+
+  @Override
+  public final Optional<Student> find(final UUID uniqueID) throws DataMapperException {
+
+    try {
+      /* OracleDriver class cant be initilized directly */
+      Class.forName("oracle.jdbc.driver.OracleDriver");
+
+      /* Create new connection */
+      final Connection connection = DriverManager.getConnection("jdbc:oracle:thin:@localhost:1521:Oracle", "username", "password");
+
+      /* Create new Oracle compliant sql statement */
+      final String statement = "SELECT `guid`, `grade`, `studentID`, `name` FROM `students` where `guid`=?";
+      final PreparedStatement dbStatement = connection.prepareStatement(statement);
+
+      /* Set unique id in sql statement */
+      dbStatement.setString(1, uniqueID.toString());
+
+      /* Execute the sql query */
+      final ResultSet rs = dbStatement.executeQuery();
+
+      while (rs.next()) {
+
+        /* Create new student */
+        final Student student = new Student(UUID.fromString(rs.getString("guid")));
+
+        /* Set all values from database in java object */
+        student.setName(rs.getString("name"));
+        student.setGrade(rs.getString("grade").charAt(0));
+        student.setStudentId(rs.getInt("studentID"));
+
+        return Optional.of(student);
+      }
+    } catch (final SQLException | ClassNotFoundException e) {
+
+      /* Don't couple any Data Mapper to java.sql.SQLException */
+      throw new DataMapperException("Error occured reading Students from Oracle data source.", e);
+    }
+
+    /* Return empty value */
+    return Optional.empty();
+  }
+
+  @Override
+  public final void update(final Student student) throws DataMapperException {
+    try {
+
+      /* OracleDriver class cant be initilized directly */
+      Class.forName("oracle.jdbc.driver.OracleDriver");
+
+      /* Create new connection */
+      final Connection connection = DriverManager.getConnection("jdbc:oracle:thin:@localhost:1521:Oracle", "username", "password");
+
+      /* Create new Oracle compliant sql statement */
+      final String statement = "UPDATE `students` SET `grade`=?, `studentID`=?, `name`=? where `guid`=?";
+
+      final PreparedStatement dbStatement = connection.prepareStatement(statement);
+
+      /* Set java object values in sql statement */
+      dbStatement.setString(1, Character.toString(student.getGrade()));
+      dbStatement.setInt(2, student.getStudentId());
+      dbStatement.setString(3, student.getName());
+      dbStatement.setString(4, student.getGuId().toString());
+
+      /* Execute the sql query */
+      dbStatement.executeUpdate();
+
+    } catch (final SQLException | ClassNotFoundException e) {
+
+      /* Don't couple any Data Mapper to java.sql.SQLException */
+      throw new DataMapperException("Error occured reading Students from Oracle data source.", e);
+    }
+  }
+
+  @Override
+  public final void insert(final Student student) throws DataMapperException {
+    try {
+
+      /* OracleDriver class cant be initilized directly */
+      Class.forName("oracle.jdbc.driver.OracleDriver");
+
+      /* Create new connection */
+      final Connection connection = DriverManager.getConnection("jdbc:oracle:thin:@localhost:1521:Oracle", "username", "password");
+
+      /* Create new Oracle compliant sql statement */
+      final String statement = "INSERT INTO `students` (`grade`, `studentID`, `name`, `guid`) VALUES (?, ?, ?, ?)";
+      final PreparedStatement dbStatement = connection.prepareStatement(statement);
+
+      /* Set java object values in sql statement */
+      dbStatement.setString(1, Character.toString(student.getGrade()));
+      dbStatement.setInt(2, student.getStudentId());
+      dbStatement.setString(3, student.getName());
+      dbStatement.setString(4, student.getGuId().toString());
+
+      /* Execute the sql query */
+      dbStatement.executeUpdate();
+
+    } catch (final SQLException | ClassNotFoundException e) {
+
+      /* Don't couple any Data Mapper to java.sql.SQLException */
+      throw new DataMapperException("Error occured reading Students from Oracle data source.", e);
+    }
+  }
+
+  @Override
+  public final void delete(final Student student) throws DataMapperException {
+    try {
+
+      /* OracleDriver class cant be initilized directly */
+      Class.forName("oracle.jdbc.driver.OracleDriver");
+
+      /* Create new connection */
+      final Connection connection = DriverManager.getConnection("jdbc:oracle:thin:@localhost:1521:Oracle", "username", "password");
+
+      /* Create new Oracle compliant sql statement */
+      final String statement = "DELETE FROM `students` where `guid`=?";
+      final PreparedStatement dbStatement = connection.prepareStatement(statement);
+
+      /* Set java object values in sql statement */
+      dbStatement.setString(1, student.getGuId().toString());
+
+      /* Execute the sql query */
+      dbStatement.executeUpdate();
+
+    } catch (final SQLException | ClassNotFoundException e) {
+
+      /* Don't couple any Data Mapper to java.sql.SQLException */
+      throw new DataMapperException("Error occured reading Students from Oracle data source.", e);
+    }
+  }
+}

data-mapper/src/main/resources/log4j.xml

@@ -0,0 +1,41 @@
+<?xml version="1.0" encoding="UTF-8" ?>
+<!--
+
+    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.
+
+-->
+<!DOCTYPE log4j:configuration SYSTEM "log4j.dtd">
+<log4j:configuration debug="true"
+  xmlns:log4j='http://jakarta.apache.org/log4j/'>
+
+  <appender name="console" class="org.apache.log4j.ConsoleAppender">
+    <layout class="org.apache.log4j.PatternLayout">
+      <param name="ConversionPattern" value="%d{yyyy-MM-dd HH:mm:ss} %-5p %c{1}:%L - %m%n" />
+    </layout>
+  </appender>
+
+  <root>
+    <level value="INFO" />
+    <appender-ref ref="console" />
+  </root>
+
+</log4j:configuration>