Spring 基类抽取

一、基类抽取

有时候我们为了代码结构更加的简化，能够减少代码的重复率，做到DRY原则，我们通常抽取部分公共代码出来

二、原始代码

public interface IEmployeeDao  {
    void save(Employee employee);

    void update(Employee employee);

    void delete(Long t);

    Employee get(Long id);

    List<Employee> listAll();
}


@Repository("employeeDao")
public class EmployeeDaoImpl implements IEmployeeDao{

    @Setter
    private SessionFactory sessionFactory;



    @Override
    public void save(Employee dmployee) {
        Session session = sessionFactory.getCurrentSession();
        session.save(dmployee);
    }

    @Override
    public void update(Employee dmployee) {
        Session session = sessionFactory.getCurrentSession();
        session.update(dmployee);
    }

    @Override
    public void delete(Employee dmployee) {
        Session session = sessionFactory.getCurrentSession();
        session.delete(dmployee);
    }

    @Override
    public Employee get(Long id) {
          Session session = sessionFactory.getCurrentSession();
        return (Employee) session.get(Employee.class,id);
    }

    @Override
    public List<Employee> listAll() {
        Session session = sessionFactory.getCurrentSession();
       return session.createCriteria(Employee.class).list();
    }
}

三、简单抽取

基类：

/**
 * 泛型dao接口：所有dao接口的父类
 * @param <T>
 */
public interface IGenericDao<T> {
    void save(T t);

    void update(T t);

    void delete(Long t);

    T get(Long id);

    List<T> listAll();
}

abstract public  class GenericDaoImpl<T> implements IGenericDao<T> {
 
 
      // 获取真实的字节码类型
      public abstract Class<T> getTargetType();


    @Setter
    private SessionFactory sessionFactory;


    @Override
    public void save(T t) {
        Session session = sessionFactory.getCurrentSession();
        session.save(t);
    }

    @Override
    public void update(T t) {
        Session session = sessionFactory.getCurrentSession();
        session.update(t);
    }

    @Override
    public void delete(Long t) {
        Session session = sessionFactory.getCurrentSession();
       Object obj =  session.get(getTargetType(),t);
        session.delete(obj);
    }

    @Override
    public T get(Long id) {
        Session session = sessionFactory.getCurrentSession();
        return (T) session.get(getTargetType(),id);
    }

    @Override
    public List<T> listAll() {
        Session session = sessionFactory.getCurrentSession();
        return session.createCriteria(getTargetType()).list();
    }
}

具体业务类：

// 此处写非公共部分，针对于不同的业务
public interface IEmployeeDao extends IGenericDao<Employee> {

}
@Repository("employeeDao")
public class EmployeeDaoImpl extends GenericDaoImpl<Employee> implements IEmployeeDao {

    @Override
    public Class<Employee> getTargetType() {
        return Employee.class;
    }
}

四、获得泛型实体类的过程示例

API示例

五、抽取结果

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