Spring JDBCTemplate. Null pointer exception - spring

Question

I'm trying to set up a SpringMVC website from scratch, but I've hit a dead end.
I'm using autowiring to instanciate JdbcTemplate with a DataSource, but somehow I'm getting a Null pointer exception. I'd appreciate your help with this.
My AppConfig is the next:
#Configuration
#ComponentScan
public class AppConfig {
#Bean
public DriverManagerDataSource dataSource() {
DriverManagerDataSource dataSource = new DriverManagerDataSource();
dataSource.setDriverClassName("com.mysql.jdbc.Driver");
dataSource.setUrl("jdbc:mysql://localhost:3306/onlinelibrary");
dataSource.setUsername("root");
dataSource.setPassword("root");
return dataSource;
}
#Bean
public JdbcTemplate jdbcTemplate(DataSource dataSource) {
return new JdbcTemplate(dataSource);
}
/*Deleted this code, still doesn't work
#Bean
public Book Book() {
return new Book();
}
*/
}
My Book class is as follows:
#Component
public class Book {
private JdbcTemplate jdbcTemplate;
private String title;
private String author;
private String isbn;
public Book() {
}
#Autowired
public Book(JdbcTemplate jdbcTemplate) {
this.jdbcTemplate = jdbcTemplate;
}
public ModelMap getBooks() {
ModelMap model = new ModelMap();
String sql = "SELECT * FROM Books";
model.put("data", jdbcTemplate.queryForList(sql));
return model;
}
}
And this is the infamous NullPointer Exception:
Any help would be highly appreciated. I probably forgot to do something, but I can't solve it myself, and I can't find anything on StackOverflow that helps me, either (although I've read many articles by now).
UPDATE WITH MORE DATA:
My project structure is the next:
And I'm using the Book object in this controller:
#Controller
public class BookController {
#RequestMapping(value = "/", method = RequestMethod.GET)
public String getBookData(Book book, ModelMap model) {
model.put("data", book.getBooks());
return "BookView";
}
}

Answer 1

When you have #Component over the class, it means Spring will create a Bean for you provided your component scanner is scanning Book class. You don't need
#Bean
public Book Book() {
return new Book();
}
It's because of this bean that doesn't have jdbcTemplate injected which is throwing NullPointerException.
Update:
Your understanding about spring injection is wrong. I have updated the controller code that should work.
#Controller
public class BookController {
#Autowired
Book book;
#RequestMapping(value = "/", method = RequestMethod.GET)
public String getBookData(ModelMap model) {
model.put("data", book.getBooks());
return "BookView";
}
}
Update: Component Scan
#ComponentScan(basePackages = "models")
public class AppConfig {