implemented dao

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

@@ -0,0 +1,17 @@
+package mate.academy.dao;
+
+import java.util.List;
+import java.util.Optional;
+import mate.academy.model.Book;
+
+public interface BookDao {
+    Book create(Book book);
+
+    Optional<Book> findById(Long id);
+
+    List<Book> findAll();
+
+    Book update(Book book);
+
+    boolean deleteById(Long id);
+}

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

@@ -0,0 +1,115 @@
+package mate.academy.dao.impl;
+
+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.dao.BookDao;
+import mate.academy.exception.DataProcessingException;
+import mate.academy.lib.Dao;
+import mate.academy.model.Book;
+import mate.academy.util.db.ConnectionUtil;
+
+@Dao
+public class BookDaoImpl implements BookDao {
+    private static final String CANT_CREATE = "Can't store the book to the DB";
+    private static final String CANT_FIND_BY_ID = "Can't find the book with id = ";
+    private static final String CANT_FIND_ALL = "Can't find all books";
+    private static final String CANT_UPDATE = "Can't update the book with id = ";
+    private static final String CANT_DELETE = "Can't delete the book with id = ";
+
+    @Override
+    public Book create(Book book) {
+        String insertQuery = "INSERT INTO books (title,price) VALUES (?,?);";
+        try (Connection connection = ConnectionUtil.getConnection();
+                PreparedStatement statement = connection.prepareStatement(
+                        insertQuery, Statement.RETURN_GENERATED_KEYS)) {
+            statement.setString(1, book.getTitle());
+            statement.setBigDecimal(2, book.getPrice());
+            statement.executeUpdate();
+            ResultSet generatedKey = statement.getGeneratedKeys();
+            if (generatedKey.next()) {
+                Long id = generatedKey.getObject(1, Long.class);
+                book.setId(id);
+            }
+        } catch (SQLException e) {
+            throw new DataProcessingException(CANT_CREATE, e);
+        }
+        return book;
+    }
+
+    @Override
+    public Optional<Book> findById(Long id) {
+        String getByIdQuery = "SELECT * FROM books WHERE id = ? AND is_deleted = 0";
+        try (Connection connection = ConnectionUtil.getConnection();
+                PreparedStatement statement = connection.prepareStatement(getByIdQuery)) {
+            statement.setLong(1, id);
+            ResultSet resultSet = statement.executeQuery();
+            if (resultSet.next()) {
+                return Optional.of(createBook(resultSet));
+            }
+        } catch (SQLException e) {
+            throw new DataProcessingException(CANT_FIND_BY_ID + id, e);
+        }
+        return Optional.empty();
+    }
+
+    @Override
+    public List<Book> findAll() {
+        String getAllQuery = "SELECT * FROM books WHERE is_deleted = 0";
+        List<Book> books = new ArrayList<>();
+        try (Connection connection = ConnectionUtil.getConnection();
+                PreparedStatement statement = connection.prepareStatement(getAllQuery)) {
+            ResultSet resultSet = statement.executeQuery();
+            while (resultSet.next()) {
+                books.add(createBook(resultSet));
+            }
+        } catch (SQLException e) {
+            throw new DataProcessingException(CANT_FIND_ALL, e);
+        }
+        return books;
+    }
+
+    @Override
+    public Book update(Book book) {
+        String updateQuery = "UPDATE books SET title = ?, price = ? "
+                + "WHERE id = ? AND is_deleted = 0";
+        Long id = book.getId();
+        try (Connection connection = ConnectionUtil.getConnection();
+                PreparedStatement statement = connection.prepareStatement(updateQuery)) {
+            statement.setString(1, book.getTitle());
+            statement.setBigDecimal(2, book.getPrice());
+            statement.setLong(3, id);
+            int affectedRows = statement.executeUpdate();
+            if (affectedRows > 0) {
+                return book;
+            }
+        } catch (SQLException e) {
+            throw new DataProcessingException(CANT_UPDATE + id, e);
+        }
+        throw new DataProcessingException(CANT_FIND_BY_ID + id);
+    }
+
+    @Override
+    public boolean deleteById(Long id) {
+        String deletedQuery = "UPDATE books SET is_deleted = 1 WHERE id = ?";
+        try (Connection connection = ConnectionUtil.getConnection();
+                PreparedStatement statement = connection.prepareStatement(deletedQuery)) {
+            statement.setLong(1, id);
+            return statement.executeUpdate() != 0;
+        } catch (SQLException e) {
+            throw new DataProcessingException(CANT_DELETE + id, e);
+        }
+    }
+
+    private Book createBook(ResultSet resultSet) throws SQLException {
+        return new Book(
+                resultSet.getLong("id"),
+                resultSet.getString("title"),
+                resultSet.getBigDecimal("price"));
+    }
+}