Spring: Configuring bean property

[K Aditi]

I am following the PDF tutorial for Spring MVC that came along with Spring 2.5 bundle.
This may seem to be a naive question,
But I have following bean declaration in my applicationContext.xml

<bean id="productDao" class="springapp.repository.JdbcProductDao">
<property name="dataSource" ref="dataSource" />
</bean>

What I expected by this declaration is that, (in crudest terms) the class JdbcProductDao should contain a variable of type dataSourcewhich will have methods setDataSource() and getDataSource().

But class JdbcProductDao is as shown below,

public class JdbcProductDao extends SimpleJdbcDaoSupport implements ProductDao {
/** Logger for this class and subclasses */
protected final Log logger = LogFactory.getLog(getClass());
public List<Product> getProductList() {
logger.info("Getting products!");
List<Product> products = getSimpleJdbcTemplate().query(
"select id, description, price from products",
new ProductMapper());
return products;
}
public void saveProduct(Product prod) {
logger.info("Saving product: " + prod.getDescription());
                ....
logger.info("Rows affected: " + count);
}
private static class ProductMapper implements ParameterizedRowMapper<Product> {
public Product mapRow(ResultSet rs, int rowNum) throws SQLException {
Product prod = new Product();
.....
return prod;
}
}
}

SimpleJdbcDaoSupport doesn't have a field of type DataSource.
So how come the a property of "dataSource" is set for JdbcProductDao

[Edited to add 1 more question]

From what I gathered about Spring is that every Class in Spring is a bean.So setters and getters are must for every class.So, whay doesn't JdbcProductDao doesn't have any?

Thanks,
[ October 04, 2008: Message edited by: K Aditi ]

[Mark Spritzler]

Look in the SimpleJdbcDaoSupport class that you are extending.

Now, I will point out this, I would not extend that class. At the point where you go "extends SimpleJdbcDaoSupport" you are now tightly coupled with a Spring class.

The best way to do JDBC Repositories is to inject a SimpleJdbcTemplate into your Repository, and use the template. In your xml you will declare a SimpleJdbcTemplate to inject into your JdbcProductDao, which would require you to create a private instance variable to hold it, and write a setter method to inject it.

Mark

[K Aditi]

Thanks for the reply! But isn't constructor rather than a setter method preferred in this scenario?

[Mark Spritzler]

Originally posted by K Aditi:
Thanks for the reply! But isn't constructor rather than a setter method preferred in this scenario?

Not if you put @Required on the setter method.

And actually if you use @Resource on the instance var, you don't need it in the constructor or a setter.

Mark

[K Aditi]

Currently, I am not using autowiring and annotations...I am configuring it all manually...just to get of it.

Thanks,