Dao层抽取BaseDao公共方法

// IBaseDao 接口，定义公共的CRUD方法
public interface IBaseDao<T> {
    
    public void add(T t);
    public void update(T t);
    public void delete(T t);
    public T getById(int id);
    public List<T> getList(int startIndex,int pageSize);
    public int getTotalCount();

}

// BaseDaoImpl接口，实现公共的CRUD方法
public class BaseDaoImpl<T> extends HibernateDaoSupport implements IBaseDao<T> {
    private Class<T> entityClass;

    // 子类的实例化需调用父类的无参构造方法，通过构造方法获取父类的泛型类型
    public BaseDaoImpl() {

        // this.getClass() --> 子类的class对象， getGenericSuperclass() ---> 获取父类的Type
        ParameterizedType pType = (ParameterizedType) this.getClass().getGenericSuperclass();

        // 获取第一个类型参数的真实类型，只有一个泛型参数，所以写0
        // ParameterizedType 参数化类型， getActualTypeArguments()，返回表示此类型实际类型参数的Type对象的数组
        entityClass = (Class<T>) pType.getActualTypeArguments()[0];

    }

    @Override
    public void add(T t) { // 增加
        this.getHibernateTemplate().save(t);
    }

    @Override
    public void update(T t) {// 修改
        this.getHibernateTemplate().update(t);
    }

    @Override
    public void delete(T t) {// 删除
        this.getHibernateTemplate().delete(t);
    }

    @Override
    public T getById(int id) { // 查询单个对象
        return this.getHibernateTemplate().get(entityClass,id);
    }

    @Override
    public List<T> getList(int startIndex,int pageSize) { // 分页查询
        return this.getHibernateTemplate().execute(new HibernateCallback<List<T>>() {

            @Override
            public List<T> doInHibernate(Session session) throws HibernateException {
                Query query = session.createQuery("from " + entityClass.getName());
                query.setFirstResult(startIndex);
                query.setMaxResults(pageSize);
                return query.list();
            }
        });
    }

    @Override
    public int getTotalCount() { // 查询总记录数
        return this.getHibernateTemplate().execute(new HibernateCallback<Integer>() {

            @Override
            public Integer doInHibernate(Session session) throws HibernateException {
                Query query = session.createQuery("select count(*) from " + entityClass.getName());
                Long count = (Long) query.uniqueResult();
                return count.intValue();
            }
        });
    }

}

// IUserDao 继承 IBaseDao接口
public interface IUserDao extends IBaseDao<User> {

}

// UserDaoImpl 继承BaseDaoImpl类，实现 IUserDao接口
public class UserDaoImpl extends BaseDaoImpl<User> implements IUserDao {
    
}

// IBaseService接口，定义CRUD方法
public interface IBaseService<T> {
    public void add(T t);
    public void update(T t);
    public void delete(T t);
    public T getById(int id);
    public List<T> getList(int startIndex,int pageSize);
    public Page<T> getPage(String currentPage);
}

// BaseServiceImpl类，实现IBaseService接口
public abstract class BaseServiceImpl<T> implements IBaseService<T> {

    //提供一个抽象方法，让子类返回对应的子类Dao
    public abstract IBaseDao<T> getBaseDao();

    @Override
    public void add(T t) {
        getBaseDao().add(t);
    }

    @Override
    public void update(T t) {
        getBaseDao().update(t);
    }

    @Override
    public void delete(T t) {
        getBaseDao().delete(t);
    }

    @Override
    public T getById(int id) {
        return getBaseDao().getById(id);
    }

    @Override
    public List<T> getList(int startIndex,int pageSize) {
        return getBaseDao().getList(startIndex,pageSize);
    }

    @Override
    public Page<T> getPage(String currentPage) {
        Page<T> page = new Page<>(1,3);
        if(currentPage!=null){
            page.setCurrentPage(Integer.parseInt(currentPage));
        }
        int totalCount = getBaseDao().getTotalCount();
        int totalPage = totalCount%page.getPageSize()==0?totalCount/page.getPageSize():totalCount/page.getPageSize()+1;
        List<T> list = getList((page.getCurrentPage()-1)*page.getPageSize(),page.getPageSize());
        page.setTotalPage(totalPage);
        page.setList(list);
        return page;
    }
}

// IUserService 继承 IBaseService接口
public interface IUserService extends IBaseService<User> {

}

// UserServiceImpl 继承 BaseServiceImpl类，实现IUserService 接口
public class UserServiceImpl extends BaseServiceImpl<User> implements IUserService {
    
    private IUserDao userDao;

    public IUserDao getUserDao() {
        return userDao;
    }

    public void setUserDao(IUserDao userDao) {
        this.userDao = userDao;
    }

    @Override
    public IBaseDao<User> getBaseDao() {
        return userDao;
    }
}