Java reflection application cases

Source: Internet
Author: User

Java reflection application cases

Scenario: on a shopping website, there are first-level classified entities, second-level classified entities, and commodity entities. operations on the three entities mapped to the database include: delete a record, save a record, search for a record by id, and modify a record. If we do not use reflection, follow the general syntax, we need to add, delete, modify, and query the DAO of the three entities. If we use the reflection mechanism, we only need to define a base class generic DAO to implement all the operations, and then let the other three DAO inherit the BaseDAO, then, through reflection, we can identify the specific entity types during the running process to implement operations.

BaseDao. java

Import java. util. List;
Public interface BaseDao {
Public void save (T t );
Public void update (T t );
Public void delete (T t );
Public T findById (Integer id );
Public T findById (String id );
Public List FindAll ();
}

CategoryDao. java

Public interface CategoryDao extends BaseDao {}


CategorySecondDao. java
Public interface CategorySecondDao extends BaseDao {}

ProductDao. java

Public interface ProductDao extends BaseDao {

List FindHotProduct (); // you can use other methods.

}

 

BaseDaoImpl. java

Public class BaseDaoImpl Extends HibernateDaoSupport implements BaseDao {
Private Class clazz;

Public BaseDaoImpl (){
// Obtain the Class Object:
Class c = this. getClass ();
System. out. println (c );
Type type = c. getGenericSuperclass ();
ParameterizedType pType = (ParameterizedType) type;
System. out. println (pType );
Type [] types = pType. getActualTypeArguments ();
This. clazz = (Class) types [0]; // obtain the specific type
}
@ Override
Public void delete (T t ){
This. getHibernateTemplate (). delete (t );
}
@ Override
Public List FindAll (){
String hql = from + clazz. getSimpleName ();
Return this. getHibernateTemplate (). find (hql );
}
@ Override
Public T findById (Integer id ){
Return (T) this. getHibernateTemplate (). get (clazz, id );
}
@ Override
Public T findById (String id ){
Return (T) this. getHibernateTemplate (). get (clazz, id );
}
@ Override
Public void save (T t ){
This. getHibernateTemplate (). save (t );
}
@ Override
Public void update (T t ){
This. getHibernateTemplate (). update (t );
}

CategoryDaoImpl. java

Public class CategoryDaoImpl extends BaseDaoImpl Implements CategoryDao {
}

CategorySecondDaoImpl. java

Public class CategorySecondDaoImpl extends BaseDaoImpl Implements CategorySecondDao {}

ProductDaoImpl. java

Public class ProductDaoImpl extends BaseDaoImpl Implements ProductDao {

Public List FindHotProduct (){
DetachedCriteria criteria = DetachedCriteria. forClass (Product. class );
Criteria. add (Restrictions. eq (is_hot, 1 ));
Criteria. addOrder (Order. desc (pdate ));
Return this. getHibernateTemplate (). findByCriteria (criteria, 0, 10 );
}

 

 

 

Related Article

Contact Us

The content source of this page is from Internet, which doesn't represent Alibaba Cloud's opinion; products and services mentioned on that page don't have any relationship with Alibaba Cloud. If the content of the page makes you feel confusing, please write us an email, we will handle the problem within 5 days after receiving your email.

If you find any instances of plagiarism from the community, please send an email to: info-contact@alibabacloud.com and provide relevant evidence. A staff member will contact you within 5 working days.

A Free Trial That Lets You Build Big!

Start building with 50+ products and up to 12 months usage for Elastic Compute Service

  • Sales Support

    1 on 1 presale consultation

  • After-Sales Support

    24/7 Technical Support 6 Free Tickets per Quarter Faster Response

  • Alibaba Cloud offers highly flexible support services tailored to meet your exact needs.