求解答为什么Dao中总是获得不到SESSION
import java.util.List;
import org.hibernate.Session;
import org.springframework.orm.hibernate3.support.HibernateDaoSupport;
import com.ssh.dao.ShowSecretDao;
import com.ssh.entity.Secret;
public class ShowSecretDaoImpl extends HibernateDaoSupport implements
ShowSecretDao {
Session s = super.getSession(true);
public List<Secret> searchSecret() {
String hql = "from Secret";
@SuppressWarnings("unchecked")
List<Secret> secretList = super.getHibernateTemplate().find(hql);
return secretList;
}
public void addSecret(Secret secret) {
//getSessionFactory().openSession().save(secret);//这个方法可以成功
s.save(secret);//这个方法不成功
}
}
如上述的dao中，//getSessionFactory().openSession().save(secret); 这个能执行插入数据
但是如果使用s.save(secret);//就会报错，NullPointerException
错误详细信息：
Could not instantiate bean class [com.ssh.dao.impl.ShowSecretDaoImpl]: Constructor threw exception; nested exception is java.lang.NullPointerException
Error creating bean with name 'showSecretDao' defined in file [D:\eclipse\dev\workspace\.metadata\.plugins\org.eclipse.wst.server.core\tmp0\wtpwebapps\mysecret_ssh\WEB-INF\classes\applicationContext.xml]: Instantiation of bean failed; nested exception is org.springframework.beans.BeanInstantiationException: Could not instantiate bean class [com.ssh.dao.impl.ShowSecretDaoImpl]: Constructor threw exception; nested exception is java.lang.NullPointerException
Error creating bean with name 'showSecretService' defined in file [D:\eclipse\dev\workspace\.metadata\.plugins\org.eclipse.wst.server.core\tmp0\wtpwebapps\mysecret_ssh\WEB-INF\classes\applicationContext.xml]: Cannot resolve reference to bean 'showSecretDao' while setting bean property 'showSecretDao'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'showSecretDao' defined in file [D:\eclipse\dev\workspace\.metadata\.plugins\org.eclipse.wst.server.core\tmp0\wtpwebapps\mysecret_ssh\WEB-INF\classes\applicationContext.xml]: Instantiation of bean failed; nested exception is org.springframework.beans.BeanInstantiationException: Could not instantiate bean class [com.ssh.dao.impl.ShowSecretDaoImpl]: Constructor threw exception; nested exception is java.lang.NullPointerException
Unable to instantiate Action, com.ssh.action.ShowSecretAction, defined for 'show' in namespace '/'Error creating bean with name 'showSecretService' defined in file [D:\eclipse\dev\workspace\.metadata\.plugins\org.eclipse.wst.server.core\tmp0\wtpwebapps\mysecret_ssh\WEB-INF\classes\applicationContext.xml]: Cannot resolve reference to bean 'showSecretDao' while setting bean property 'showSecretDao'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'showSecretDao' defined in file [D:\eclipse\dev\workspace\.metadata\.plugins\org.eclipse.wst.server.core\tmp0\wtpwebapps\mysecret_ssh\WEB-INF\classes\applicationContext.xml]: Instantiation of bean failed; nested exception is org.springframework.beans.BeanInstantiationException: Could not instantiate bean class [com.ssh.dao.impl.ShowSecretDaoImpl]: Constructor threw exception; nested exception is java.lang.NullPointerException
给大家看下我的Spring-application.xml 和hibernate.cfg.xml
Application.xml
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:aop="http://www.springframework.org/schema/aop"
xmlns:tx="http://www.springframework.org/schema/tx"
xsi:schemaLocation="
http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.5.xsd
http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-2.5.xsd
http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-2.5.xsd">
<bean id="sessionFactory"
class="org.springframework.orm.hibernate4.LocalSessionFactoryBean">
<property name="configLocation">
<value>WEB-INF/hibernate.cfg.xml </value>
</property>
</bean>
<!-- action -->
<bean id="showSecretAction" scope="prototype"
class="com.ssh.action.ShowSecretAction">
<property name="showSecretService" ref="showSecretService"></property>
</bean>
<!-- service -->
<bean id="showSecretService" scope="prototype"
class="com.ssh.service.impl.ShowSecretServiceImpl">
<property name="showSecretDao" ref="showSecretDao"></property>
</bean>
<!-- dao -->
<bean id="showSecretDao" scope="prototype"
class="com.ssh.dao.impl.ShowSecretDaoImpl">
<property name="sessionFactory" ref="sessionFactory"></property>
</bean>
</beans>
Hibernate
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-configuration PUBLIC
"-//Hibernate/Hibernate Configuration DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
<session-factory>
<!-- 显示实际操作数据库时的SQL -->
<property name="show_sql">true</property>
<!-- SQL方言，这边设定的是MySQL -->
<property name="dialect">org.hibernate.dialect.MySQLDialect</property>
<!--驱动程序，在后续的章节中将讲述mysql、sqlserver和Oracle数据库的配置 -->
<property name="connection.driver_class">com.mysql.jdbc.Driver</property>
<!-- JDBC URL -->
<property name="connection.url">jdbc:mysql://*********:3306/secret</property>
<property name="connection.useUnicode">true</property>
<property name="connection.characterEncoding">UTF-8</property>
<!-- 数据库用户名 -->
<property name="connection.username">root</property>
<!-- 数据库密码 -->
<property name="connection.password">*******</property>
<property name="c3p0.min_size">5</property>
<property name="c3p0.max_size">20</property>
<property name="c3p0.timeout">1800</property>
<property name="c3p0.max_statements">50</property>
<!-- 对象与数据库表格映像文件 -->
<mapping resource="com/ssh/entity/secret.hbm.xml" />
</session-factory>
</hibernate-configuration>
貌似数据库连接上是没什么问题，因为试用getSession的方式能成功插入数据，
求解答。 --------------------编程问答-------------------- 你继承了HibernateDaoSupport，最好也要把HibernateDaoSupport这个代码帖出来啊。你的super.getSession();看看是不是空嘛。打印下喽。应该是注入的时候没成功。
--------------------编程问答--------------------
既然都实现HibernateDaoSupport 这个类了，干嘛还要通过session来保持数据？通过HibernateTemplate类增、删、改、查吧，至于为什么报空你去父类的getSession(boolean f)这个方法中去看吧！ --------------------编程问答--------------------
HibernateDaoSupport 是系统的类啊。这不是hibernate提供的嘛。我自己没写过这个 类。 --------------------编程问答--------------------
super.getHibernateTemplate().find(hql) 这种方式也是报空指针异常的。 --------------------编程问答-------------------- 这种方式
Session s = super.getSession(true);
应该是先被spring注入，后才被置空了的吧 --------------------编程问答-------------------- 既然 继承了 HibernateDaoSupport 为什么还要自己 拿session难道 你要自己做事务吗直接
getHibernateTemplate().save(HQL)
getSessionFactory().openSession().save(secret); 想不通 还要这个 有什么用 --------------------编程问答-------------------- 回复于： 2013-05-22 12:55:37
你继承了HibernateDaoSupport，最好也要把HibernateDaoSupport这个代码帖出来啊。你的super.getSession();看看是不是空嘛。打印下喽。应该是注入的时候没成功。 --------------------编程问答--------------------
因为用getHibernateTemplate().save(HQL) 这种方式 是会报错的 NullPointerException --------------------编程问答-------------------- java文件：
import org.springframework.orm.hibernate3.support.HibernateDaoSupport;
配置文件：
<bean id="sessionFactory"
class="org.springframework.orm.hibernate4.LocalSessionFactoryBean">
<property name="configLocation">
<value>WEB-INF/hibernate.cfg.xml </value>
</property>
</bean>
另外：
hibernate4不推荐使用Hibernate模板来实现持久化！
--------------------编程问答--------------------
请问应该如何解决呢，我觉得您说的是有道理的，就是持久化出现了问题
补充：Java , Web 开发
