泛型DAO模型设计

DAO接口：

import java.util.List;

import com.itheima.domain.Customer;

public interface CustomerDao extends Dao<Customer>{
    List<Customer> find();
}

import java.io.Serializable;

public interface Dao<T> {
    void add(T t);
    void update(T t);
    void delete(Serializable id);// String Integer 更加通用。联合主键
    T findOne(Serializable id);
}

import com.itheima.domain.Order;

public interface OrderDao extends Dao<Order> {

}

import java.util.List;

import com.itheima.domain.Student;

public interface StudentDao extends Dao<Student>{
    List<Student> findPageRecords(int index,int size);
}

类

import java.io.Serializable;

import org.hibernate.Session;

import com.itheima.dao.Dao;
//借助Hibernate框架
public class BaseDao<T> implements Dao<T> {
    private Session session;//核心类。Connection
                        //ORM:通过操作类，就相当于操作了数据库
                        //比如：操作Customer类，就相当于存取Customer表（Hibernate来做）
                        //操作Student类，就相当于存取Student表（Hibernate来做）
    
    private Class clazz;//实体类型，目的就是让Hibernate知道从哪个表中查数据
    public BaseDao(Class clazz){
        this.clazz = clazz;
    }
    
    public void add(T t) {
        session.save(t);
    }

    public void update(T t) {
        session.update(t);
    }

    public void delete(Serializable id) {
        T t = findOne(id);
        session.delete(t);
    }

    public T findOne(Serializable id) {
        return (T)session.get(clazz, id);//第一个参数：操作的类的类型。第二个参数，主键
    }

}

实现类

import java.util.List;

import com.itheima.dao.CustomerDao;
import com.itheima.domain.Customer;

public class CustomerDaoImpl extends BaseDao<Customer> implements CustomerDao {
    
    public CustomerDaoImpl(){
        super(Customer.class);
    }
    
    public List<Customer> find() {
        return null;
    }

}

import java.io.Serializable;

import com.itheima.dao.OrderDao;
import com.itheima.domain.Order;

public class OrderDaoImpl extends BaseDao<Order> implements OrderDao {
    public OrderDaoImpl(){
        super(Order.class);
    }
}

import java.util.List;

import com.itheima.dao.StudentDao;
import com.itheima.domain.Student;

public class StudentDaoImpl extends BaseDao<Student> implements StudentDao {
    public StudentDaoImpl(){
        super(Student.class);
    }
    public List<Student> findPageRecords(int index, int size) {
        // TODO Auto-generated method stub
        return null;
    }

}

实体类

public class Order {

}

public class Student {

}

public class Customer {

}

 自定义泛型及泛型的反射