NullPointerException 使用 Spring 使 Generic Dao 休眠
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【中文标题】NullPointerException 使用 Spring 使 Generic Dao 休眠【英文标题】：NullPointerException hibernate Generic Dao with Spring 【发布时间】：2018-01-14 06:14:27 【问题描述】：我有一个业务逻辑类，它尝试使用从通用 Dao 保存的 dao 方法，这是来自 bl 的代码。
public void setUsuario(Usuario usuario)
this.usuario = usuario;
usuarioDao.save(usuario);
调试我发现用户对象正确填充了数据，而DaoImpl就是这个
@Component
public class UsuarioDaoImpl extends GenericDaoImpl<Usuario> implements UsuarioDao
@Override
public Usuario get(String id) throws DataAccessException
// TODO Auto-generated method stub
return null;
@Override
public boolean saveBatchFull(Collection<Usuario> entity, boolean update) throws DataAccessException
// TODO Auto-generated method stub
return false;
@Override
public Usuario get(Long id) throws DataAccessException
// TODO Auto-generated method stub
return null;
@Override
public boolean save(Usuario usuario) throws DataAccessException
super.save(usuario);
return false;
这是我使用的通用类。
import java.lang.reflect.ParameterizedType;
import java.util.Collection;
import java.util.Iterator;
import org.slf4j.LoggerFactory;
import org.apache.log4j.LogManager;
import org.apache.logging.log4j.*;
import org.apache.log4j.LogManager;
import org.apache.log4j.Logger;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.dao.DataAccessException;
import org.springframework.transaction.annotation.Transactional;
public class GenericDaoImpl<T> implements GenericDao<T>
private static final Logger logger = LogManager.getLogger("GenericDaoImpl");
protected Class<T> domainClass;
// @Autowired(required = true)
protected SessionFactory sessionFactory;
// Para conexion sin Injection Dependency
private Transaction transactionNoID;
public GenericDaoImpl()
// Constructor default
// Obtener el objeto
@SuppressWarnings( "unchecked", "rawtypes" )
protected Class<T> getDomainClass()
if ( domainClass == null )
ParameterizedType thisType = (ParameterizedType) getClass().getGenericSuperclass();
domainClass = (Class) thisType.getActualTypeArguments()[0];
return domainClass;
@SuppressWarnings("unchecked")
@Transactional(readOnly = true)
public T get(Long id) throws DataAccessException
Session session = null;
if ( sessionFactory != null )
session = this.sessionFactory.getCurrentSession();
String listQuery;
StringBuilder sb = new StringBuilder(" from ");
sb.append(this.getDomainClass().getName());
sb.append(" entity ");
sb.append(" where id = :id ");
listQuery = sb.toString();
T result = null;
if ( session == null )
session = SessionFactoryUtil.getSessionFactory().openSession();
try
result = (T) session.createQuery(listQuery).setLong("id", id).uniqueResult();
catch (Exception e)
e.printStackTrace();
logger.info("Error en la clase: " + this.getClass().getName() + " - " + e.getMessage());
finally
session.close();
else
try
result = (T) session.createQuery(listQuery).setLong("id", id).uniqueResult();
catch (Exception e)
e.printStackTrace();
logger.info("Error en la clase: " + this.getClass().getName() + " - " + e.getMessage());
return result;
@SuppressWarnings("unchecked")
@Transactional(readOnly = true)
public T get(String id) throws DataAccessException
Session session = null;
if ( sessionFactory != null )
session = this.sessionFactory.getCurrentSession();
String listQuery;
StringBuilder sb = new StringBuilder(" from ");
sb.append(this.getDomainClass().getName());
sb.append(" entity ");
sb.append(" where id = :id ");
listQuery = sb.toString();
T result = null;
if ( session == null )
session = SessionFactoryUtil.getSessionFactory().openSession();
try
result = (T) session.createQuery(listQuery).setString("id", id).uniqueResult();
catch (Exception e)
e.printStackTrace();
logger.info("Error en la clase: " + this.getClass().getName() + " - " + e.getMessage());
finally
session.close();
else
try
result = (T) session.createQuery(listQuery).setString("id", id).uniqueResult();
catch (Exception e)
e.printStackTrace();
logger.info("Error en la clase: " + this.getClass().getName() + " - " + e.getMessage());
return result;
@SuppressWarnings("unchecked")
@Transactional(readOnly = true)
public Collection<T> list() throws DataAccessException
Session session = null;
if ( sessionFactory != null )
session = this.sessionFactory.getCurrentSession();
String listQuery;
StringBuilder sb = new StringBuilder(" from ");
sb.append(this.getDomainClass().getName());
sb.append(" entity ");
listQuery = sb.toString();
Collection<T> result = null;
if ( session == null )
session = SessionFactoryUtil.getSessionFactory().openSession();
try
result = session.createQuery(listQuery).list();
catch (Exception e)
e.printStackTrace();
logger.info("Error en la clase: " + this.getClass().getName() + " - " + e.getMessage());
finally
session.close();
else
try
result = session.createQuery(listQuery).list();
catch (Exception e)
e.printStackTrace();
logger.info("Error en la clase: " + this.getClass().getName() + " - " + e.getMessage());
return result;
@SuppressWarnings("unchecked")
@Transactional(readOnly = true)
public Collection<T> listById(Long id) throws DataAccessException
Session session = null;
if ( sessionFactory != null )
session = this.sessionFactory.getCurrentSession();
String listQuery;
StringBuilder sb = new StringBuilder(" from ");
sb.append(this.getDomainClass().getName());
sb.append(" entity ");
sb.append(" where id = :id ");
listQuery = sb.toString();
Collection<T> result = null;
if ( session == null )
session = SessionFactoryUtil.getSessionFactory().openSession();
try
result = session.createQuery(listQuery).setLong("id", id).list();
catch (Exception e)
e.printStackTrace();
logger.info("Error en la clase: " + this.getClass().getName() + " - " + e.getMessage());
finally
session.close();
else
try
result = session.createQuery(listQuery).setLong("id", id).list();
catch (Exception e)
e.printStackTrace();
logger.info("Error en la clase: " + this.getClass().getName() + " - " + e.getMessage());
return result;
@SuppressWarnings("unchecked")
@Transactional(readOnly = true)
public Collection<T> listById(String id) throws DataAccessException
Session session = null;
if ( sessionFactory != null )
session = this.sessionFactory.getCurrentSession();
String listQuery;
StringBuilder sb = new StringBuilder(" from ");
sb.append(this.getDomainClass().getName());
sb.append(" entity ");
sb.append(" where id = :id ");
listQuery = sb.toString();
Collection<T> result = null;
if ( session == null )
session = SessionFactoryUtil.getSessionFactory().openSession();
try
result = session.createQuery(listQuery).setString("id", id).list();
catch (Exception e)
e.printStackTrace();
logger.info("Error en la clase: " + this.getClass().getName() + " - " + e.getMessage());
finally
session.close();
else
try
result = session.createQuery(listQuery).setString("id", id).list();
catch (Exception e)
e.printStackTrace();
logger.info("Error en la clase: " + this.getClass().getName() + " - " + e.getMessage());
return result;
@Transactional
public boolean save(Object entity) throws DataAccessException
Session session = null;
if ( sessionFactory != null )
session = this.sessionFactory.getCurrentSession();
if ( session == null )
session = SessionFactoryUtil.getSessionFactory().openSession();
try
transactionNoID = session.beginTransaction();
session.saveOrUpdate(entity);
transactionNoID.commit();
return true;
catch (Exception e)
transactionNoID.rollback();
e.printStackTrace();
logger.info("Error en la clase: " + this.getClass().getName() + " - " + e.getMessage());
finally
session.close();
else
try
session.saveOrUpdate(entity);
catch (Exception e)
e.printStackTrace();
logger.info("Error en la clase: " + this.getClass().getName() + " - " + e.getMessage());
return false;
@Transactional
public boolean saveNoUpdate(Object entity) throws DataAccessException
Session session = null;
if ( sessionFactory != null )
session = this.sessionFactory.getCurrentSession();
if ( session == null )
session = SessionFactoryUtil.getSessionFactory().openSession();
try
transactionNoID = session.beginTransaction();
session.save(entity);
transactionNoID.commit();
return true;
catch (Exception e)
transactionNoID.rollback();
e.printStackTrace();
logger.info("Error en la clase: " + this.getClass().getName() + " - " + e.getMessage());
finally
session.close();
else
try
session.save(entity);
catch (Exception e)
e.printStackTrace();
logger.info("Error en la clase: " + this.getClass().getName() + " - " + e.getMessage());
return false;
@SuppressWarnings( "unchecked", "rawtypes" )
@Transactional
@Override
public boolean saveBatchFull(Collection<T> entity, boolean update) throws DataAccessException
Session session = null;
if ( sessionFactory != null )
session = this.sessionFactory.getCurrentSession();
if ( session == null )
session = SessionFactoryUtil.getSessionFactory().openSession();
try
transactionNoID = session.beginTransaction();
for (Iterator iterator = entity.iterator(); iterator.hasNext();)
T t = (T) iterator.next();
if ( update )
session.saveOrUpdate(t);
else
session.save(t);
transactionNoID.commit();
return true;
catch (Exception e)
transactionNoID.rollback();
e.printStackTrace();
logger.info("Error en la clase: " + this.getClass().getName() + " - " + e.getMessage());
finally
session.close();
else
try
for (Iterator iterator = entity.iterator(); iterator.hasNext();)
T t = (T) iterator.next();
if ( update )
session.saveOrUpdate(t);
else
session.save(t);
return true;
catch (Exception e)
e.printStackTrace();
logger.info("Error en la clase: " + this.getClass().getName() + " - " + e.getMessage());
return false;
public SessionFactory getSessionFactory()
return sessionFactory;
@Transactional
public void flush() throws DataAccessException
sessionFactory.getCurrentSession().flush();
有人可以帮助理解为什么当对象用户在 save() 中使用时出现此错误。
谢谢。
【问题讨论】：
你正在混合容器管理事务和 bean 管理事务，它不会工作。既然你用的是spring，可以跟着教程spring.io/guides/gs/accessing-data-jpa @André 对不起，我是网络开发的新手，我发现你的回答真的很混乱 您没有让 Spring 为您管理事务。您只需要@Autowired 和@Transaction。该教程是您需要的一切。刮掉所有内容并阅读有关 Spring JPA 的其他一些教程，直到您掌握了窍门。让您的代码工作不会走得太远。
@André 谢谢，我会检查你的链接，我错过了很多概念，这不会让我完成我的工作。
【参考方案1】：
确保容器创建 dao 对象 bean 并注入您的服务类 尝试关注--
确保您在标签/注释之后添加了 spring 配置文件/类--
@ComponentScan(BasePackages="fully Qualified dao class name")
或<context:component-scan="fully Qualified dao class name">
【讨论】：
嗨，我的上下文：component-scan 有我认为正确的项目主文件夹吗？谢谢 确保您在 dao 类中使用了 '@repository' 或 '@component' 注释【参考方案2】：感谢大家的帮助，我的休眠会话 bean 声明中有一个错误
【讨论】：
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