package com.springmvc.repository.impl;
...
@Repository
public class BookRepositoryImpl implements BookRepository {
    ...

➊

    public List<Book> getBookListByCategory(String category) {
        List<Book> booksByCategory = new ArrayList<Book>();
        String SQL = "SELECT * FROM book where b_category LIKE '%" + category + "%'"; ➋
        booksByCategory = template.query(SQL, new BookRowMapper()); ➌
        return booksByCategory;
    }

}