public class DatabaseConfig {
private static final String JDBC_URL = "jdbc:mysql://localhost:3306/library";
private static final String USERNAME = "root";
private static final String PASSWORD = "password";
public static Connection getConnection() {
Connection connection = null;
try {
connection = DriverManager.getConnection(JDBC_URL, USERNAME, PASSWORD);
} catch (SQLException e) {
e.printStackTrace();
}
return connection;
}
}
public class BookDao {
public List<Book> getAllBooks() {
List<Book> books = new ArrayList<>();
Connection connection = DatabaseConfig.getConnection();
Statement statement = null;
ResultSet resultSet = null;
try {
statement = connection.createStatement();
resultSet = statement.executeQuery("SELECT * FROM books");
while (resultSet.next()) {
int id = resultSet.getInt("id");
String title = resultSet.getString("title");
String author = resultSet.getString("author");
float price = resultSet.getFloat("price");
books.add(new Book(id, title, author, price));
}
} catch (SQLException e) {
e.printStackTrace();
} finally {
try {
resultSet.close();
statement.close();
connection.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
return books;
}
}
public class BookCache {
private static final Map<String, List<Book>> cache = new ConcurrentHashMap<>();
public List<Book> getBooksByCategory(String category) {
if (cache.containsKey(category)) {
return cache.get(category);
} else {
List<Book> books = BookDao.getAllBooksByCategory(category);
cache.put(category, books);
return books;
}
}
}
public class Main {
public static void main(String[] args) {
BookCache cache = new BookCache();
List<Book> books = cache.getBooksByCategory("Science");
for (Book book : books) {
System.out.println(book.getTitle() + " - " + book.getAuthor());
}
}
}
