Code review and Dao optimization--BaseDao

Posted on | In |

Reflection: .java to .class, to get .class

  • Class.forName(…)
  • “ClassName”.class
  • “object”.getClass(), this method is in class “Object”

Generic: <>–typeof

Dao optimization:

  • New interface “BaseDao” and its implementing class “BaseDaoImpl”
    1
    2
    3
    4
    5
    6
    7
    public interface BaseDao<T> {
    	void add(T t);
    	void update(T t);
    	void delete(T t);
    	T findById(int id);
    	List<T> findAll();
    }
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
public class BaseDaoImpl<T> extends HibernateDaoSupport implements BaseDao<T> {
	private Class pClass;
	public BaseDaoImpl() {
		// get running class which one extends BaseDaoImpl, here is
		// CustomerDaoImpl
		Class clazz = this.getClass();
		// get BaseDaoImpl<Customer>, import java.lang.reflect.Type
		Type type = clazz.getGenericSuperclass();
		ParameterizedType pType = (ParameterizedType) type;
		// get <Customer>
		Type[] types = pType.getActualTypeArguments();
		Class tClass = (Class) types[0];
		pClass = tClass;
	}
	public void add(T t) {
		this.getHibernateTemplate().save(t);
	}
	public void update(T t) {
		this.getHibernateTemplate().update(t);
	}
	public void delete(T t) {
		this.getHibernateTemplate().delete(t);
	}
	// cannot code like T.class
	public T findById(int id) {
		// return (T) this.getHibernateTemplate().get(T.class, id);
		return (T) this.getHibernateTemplate().get(pClass, id);
	}
	public List<T> findAll() {
		// return this.getHibernateTemplate().find("from ", T);
		return (List<T>) this.getHibernateTemplate().find("from " + pClass.getSimpleName());
	}
}
  • Let normal interface Dao to extends BaseDao, then I can delete repetitive methods in normal interface Dao file.
    public interface CustomerDao extends BaseDao<Customer>{...} // here CustomerDao is a concrete interface
  • Let normal class Dao to extends BaseDaoImpl, then I can delete repetitive methods in normal class Dao file. The normal class do not need to extends HibernateDaoSupport because it has been done in BaseDaoImpl.
    public class CustomerDaoImpl extends BaseDaoImpl<Customer> implements CustomerDao{...}
    here CustomerDaoImpl is a concrete class