created Book entity and DAO implementation

- created Book entity, BookDao interface, and BookDaoImpl class with CRUD operations;
- added database connection management through ConnectionManager and properties handling via PropertiesUtil.
- Updated Main to test CRUD operations.

.gitignore

@@ -1,3 +1,3 @@
 .idea/*
 *.iml
-target/*
+target/*

pom.xml

@@ -55,4 +55,13 @@
             </plugins>
         </pluginManagement>
     </build>
+
+    <dependencies>
+        <dependency>
+            <groupId>com.mysql</groupId>
+            <artifactId>mysql-connector-j</artifactId>
+            <version>9.0.0</version>
+        </dependency>
+
+    </dependencies>
 </project>

src/main/java/mate/academy/Main.java

@@ -1,7 +1,48 @@
 package mate.academy;
 
+import java.math.BigDecimal;
+import mate.academy.dao.BookDao;
+import mate.academy.entity.Book;
+import mate.academy.lib.Injector;
+
 public class Main {
+    private static final Injector injector = Injector.getInstance("mate.academy");
+
     public static void main(String[] args) {
+        Book coreJavaVol1 = new Book();
+        coreJavaVol1.setTitle("Core Java: Fundamentals, Volume 1");
+        coreJavaVol1.setPrice(new BigDecimal("50.59"));
+
+        Book coreJavaVol2 = new Book();
+        coreJavaVol2.setTitle("Core Java: Advanced Features, Volume 2");
+        coreJavaVol2.setPrice(new BigDecimal("48.38"));
+
+        Book javaSE8 = new Book();
+        javaSE8.setTitle("Java SE 8. Programmer I Exam Guide");
+        javaSE8.setPrice(new BigDecimal("35.99"));
+
+        BookDao bookDao = (BookDao) injector.getInstance(BookDao.class);
+
+        // create
+        System.out.println(bookDao.create(coreJavaVol1));
+        System.out.println(bookDao.create(coreJavaVol2));
+        System.out.println(bookDao.create(javaSE8));
+
+        // findById
+        System.out.println(bookDao.findById(1L));
+        System.out.println(bookDao.findById(2L));
+        System.out.println(bookDao.findById(3L));
+
+        // findAll
+        System.out.println(bookDao.findAll());
+
+        // update
+        coreJavaVol1.setId(1L);
+        coreJavaVol1.setPrice(new BigDecimal(60));
+        System.out.println(bookDao.update(coreJavaVol1));
+
+        // deleteById
+        System.out.println(bookDao.delete(1L));
 
     }
 }

src/main/java/mate/academy/dao/BookDao.java

@@ -0,0 +1,16 @@
+package mate.academy.dao;
+
+import java.util.List;
+import java.util.Optional;
+
+public interface BookDao<K, E> {
+    E create(E book);
+
+    Optional<E> findById(K id);
+
+    List<E> findAll();
+
+    E update(E book);
+
+    boolean delete(K id);
+}

src/main/java/mate/academy/dao/BookDaoImpl.java

@@ -0,0 +1,116 @@
+package mate.academy.dao;
+
+import java.sql.Connection;
+import java.sql.PreparedStatement;
+import java.sql.ResultSet;
+import java.sql.SQLException;
+import java.sql.Statement;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Optional;
+import mate.academy.entity.Book;
+import mate.academy.exception.DataProcessingException;
+import mate.academy.lib.Dao;
+import mate.academy.util.ConnectionManager;
+
+@Dao
+public class BookDaoImpl implements BookDao<Long, Book> {
+    private static final String SQL_INSERT = "INSERT INTO books (title, price) VALUES (?, ?)";
+    private static final String SQL_FIND_BY_ID = "SELECT * FROM books WHERE id = ?";
+    private static final String SQL_FIND_ALL = "SELECT * FROM books";
+    private static final String SQL_UPDATE = "UPDATE books SET title = ?, price = ? WHERE id = ?";
+    private static final String SQL_DELETE = "DELETE FROM books WHERE id = ?";
+
+    @Override
+    public Book create(Book book) {
+        try (Connection connection = ConnectionManager.open();
+                PreparedStatement statement = connection.prepareStatement(SQL_INSERT,
+                        Statement.RETURN_GENERATED_KEYS)) {
+            statement.setString(1, book.getTitle());
+            statement.setBigDecimal(2, book.getPrice());
+            int affectedRows = statement.executeUpdate();
+            validateAffectedRows(affectedRows);
+            ResultSet generatedKeys = statement.getGeneratedKeys();
+            if (generatedKeys.next()) {
+                book.setId(generatedKeys.getLong(1));
+            }
+            return book;
+        } catch (SQLException e) {
+            throw new DataProcessingException("Can't add new book: " + book, e);
+        }
+    }
+
+    @Override
+    public Optional<Book> findById(Long id) {
+        try (Connection connection = ConnectionManager.open();
+                PreparedStatement statement = connection.prepareStatement(SQL_FIND_BY_ID)) {
+            statement.setLong(1, id);
+            ResultSet resultSet = statement.executeQuery();
+            Book book = null;
+            if (resultSet.next()) {
+                book = buildBook(resultSet);
+            }
+            return Optional.ofNullable(book);
+        } catch (SQLException e) {
+            throw new DataProcessingException("Can't find book with id: " + id, e);
+        }
+    }
+
+    @Override
+    public List<Book> findAll() {
+        try (Connection connection = ConnectionManager.open();
+                PreparedStatement statement = connection.prepareStatement(SQL_FIND_ALL)) {
+            ResultSet resultSet = statement.executeQuery();
+            List<Book> books = new ArrayList<>();
+            while (resultSet.next()) {
+                books.add(buildBook(resultSet));
+            }
+            return books;
+        } catch (SQLException e) {
+            throw new DataProcessingException("Can't retrieve books", e);
+        }
+    }
+
+    @Override
+    public Book update(Book book) {
+        try (Connection connection = ConnectionManager.open();
+                PreparedStatement statement = connection.prepareStatement(SQL_UPDATE)) {
+            statement.setString(1, book.getTitle());
+            statement.setBigDecimal(2, book.getPrice());
+            statement.setLong(3, book.getId());
+            int updateCount = statement.executeUpdate();
+            validateAffectedRows(updateCount);
+            return book;
+        } catch (SQLException e) {
+            throw new DataProcessingException("Can't update book: " + book, e);
+        }
+    }
+
+    @Override
+    public boolean delete(Long id) {
+        try (Connection connection = ConnectionManager.open();
+                PreparedStatement statement = connection.prepareStatement(SQL_DELETE)) {
+            statement.setLong(1, id);
+            int deleteCount = statement.executeUpdate();
+            return deleteCount > 0;
+        } catch (SQLException e) {
+            throw new DataProcessingException("Can't delete book with id: " + id, e);
+        }
+    }
+
+    private static void validateAffectedRows(int affectedRows) {
+        if (affectedRows < 1) {
+            throw new DataProcessingException(
+                    "Expected to insert at least one row, but inserted 0 rows",
+                    null);
+        }
+    }
+
+    private static Book buildBook(ResultSet resultSet) throws SQLException {
+        return new Book(
+                resultSet.getLong("id"),
+                resultSet.getString("title"),
+                resultSet.getBigDecimal("price")
+        );
+    }
+}

src/main/java/mate/academy/entity/Book.java

@@ -0,0 +1,51 @@
+package mate.academy.entity;
+
+import java.math.BigDecimal;
+
+public class Book {
+    private Long id;
+    private String title;
+    private BigDecimal price;
+
+    public Book(Long id, String title, BigDecimal price) {
+        this.id = id;
+        this.title = title;
+        this.price = price;
+    }
+
+    public Book() {
+    }
+
+    public Long getId() {
+        return id;
+    }
+
+    public void setId(Long id) {
+        this.id = id;
+    }
+
+    public String getTitle() {
+        return title;
+    }
+
+    public void setTitle(String title) {
+        this.title = title;
+    }
+
+    public BigDecimal getPrice() {
+        return price;
+    }
+
+    public void setPrice(BigDecimal price) {
+        this.price = price;
+    }
+
+    @Override
+    public String toString() {
+        return "Book{"
+               + "id=" + id
+               + ", title='" + title + '\''
+               + ", price=" + price
+               + '}';
+    }
+}

src/main/java/mate/academy/exception/DataProcessingException.java

@@ -0,0 +1,7 @@
+package mate.academy.exception;
+
+public class DataProcessingException extends RuntimeException {
+    public DataProcessingException(String message, Throwable cause) {
+        super(message, cause);
+    }
+}

src/main/java/mate/academy/util/ConnectionManager.java

@@ -0,0 +1,40 @@
+package mate.academy.util;
+
+import java.sql.Connection;
+import java.sql.DriverManager;
+import java.sql.SQLException;
+import mate.academy.exception.DataProcessingException;
+
+public class ConnectionManager {
+    private static final String USERNAME_KEY = "db.username";
+    private static final String PASSWORD_KEY = "db.password";
+    private static final String URL_KEY = "db.url";
+
+    static {
+        loadDriver();
+    }
+
+    public ConnectionManager() {
+    }
+
+    public static Connection open() {
+        try {
+            return DriverManager.getConnection(
+                    PropertiesUtil.get(URL_KEY),
+                    PropertiesUtil.get(USERNAME_KEY),
+                    PropertiesUtil.get(PASSWORD_KEY)
+            );
+        } catch (SQLException e) {
+            throw new DataProcessingException("Failed to establish database connection", e);
+        }
+    }
+
+    private static void loadDriver() {
+        try {
+            Class.forName("com.mysql.cj.jdbc.Driver");
+        } catch (ClassNotFoundException e) {
+            throw new DataProcessingException("Can't load JDBC driver: ", e);
+        }
+    }
+
+}

src/main/java/mate/academy/util/PropertiesUtil.java

@@ -0,0 +1,31 @@
+package mate.academy.util;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.util.Properties;
+import mate.academy.exception.DataProcessingException;
+
+public class PropertiesUtil {
+    private static final String PROPERTIES_FILE = "application.properties";
+    private static final Properties PROPERTIES = new Properties();
+
+    static {
+        loadProperties();
+    }
+
+    public PropertiesUtil() {
+    }
+
+    public static String get(String key) {
+        return PROPERTIES.getProperty(key);
+    }
+
+    private static void loadProperties() {
+        try (InputStream inputStream = PropertiesUtil.class.getClassLoader()
+                .getResourceAsStream(PROPERTIES_FILE)) {
+            PROPERTIES.load(inputStream);
+        } catch (IOException e) {
+            throw new DataProcessingException("Can't get data from: " + PROPERTIES_FILE, e);
+        }
+    }
+}

src/main/resources/application.properties

@@ -0,0 +1,3 @@
+db.url=jdbc:mysql://localhost:3306/book_repository
+db.username=root
+db.password=1111

src/main/resources/init_db.sql

@@ -0,0 +1,9 @@
+CREATE DATABASE book_repository;
+
+USE book_repository;
+
+CREATE TABLE books (
+    id SERIAL PRIMARY KEY,
+    title VARCHAR(128),
+    price DECIMAL(10, 2)
+);