S2SH上空指针有关问题

package action;import dao.AccountDAO;import model.Account;public class LoginAction{    private Account account;    private AccountDAO accountDao;        public void setAccount(Account account)    {        this.account=account;    }    public Account getAccount ()    {        return account;    }    public void setAccountDao(AccountDAO accountDao)    {        this.accountDao = accountDao;    }    public AccountDAO getAccountDao()    {        return this.accountDao;    }        public String execute()     {        System.out.print(accountDao.toString());/报错         System.out.print([b]accountDao[/b].toString()+"name:"+account.getName()+"password:"+account.getPassword());        if ([b]accountDao[/b].isValid(account.getName(),account.getPassword())==true) return "success";        else return "fail";    }}

在AccountDAO中我自己实现的代码public boolean isValid(final String name,final String password) {        [b]Session session=getHibernateTemplate().getSessionFactory().openSession();[/b]        Criteria tmp=session.createCriteria(Account.class);        List result = tmp.add(Restrictions.eq("name", name))                         .add(Restrictions.eq("password", password))                         .list();        if(result.size()>0) {            return true;        } else {            return false;        }        }

<?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:p="http://www.springframework.org/schema/p"    xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd">    <bean id="dataSource"        class="org.apache.commons.dbcp.BasicDataSource">        <property name="driverClassName"            value="com.mysql.jdbc.Driver">        </property>        <property name="url"            value="jdbc:mysql://localhost:3306/large_experiment">        </property>        <property name="username" value="root"></property>        <property name="password" value="123456"></property>    </bean>    <bean id="sessionFactory"        class="org.springframework.orm.hibernate3.LocalSessionFactoryBean">        <property name="dataSource">            <ref bean="dataSource" />        </property>        <property name="hibernateProperties">            <props>                <prop key="hibernate.dialect">                    org.hibernate.dialect.MySQLDialect                </prop>            </props>        </property>        <property name="mappingResources">            <list>                <value>model/Person.hbm.xml</value>                <value>model/Account.hbm.xml</value></list>        </property></bean>    <bean id="PersonDAO" class="dao.PersonDAO">        <property name="sessionFactory">            <ref bean="sessionFactory" />        </property>    </bean>    <bean id="AccountDAO" class="dao.AccountDAO">        <property name="sessionFactory">            <ref bean="sessionFactory" />        </property>    </bean>    <bean id="LoginAction" class="action.LoginAction">        <property name="accountDao">            <ref bean="AccountDAO" />        </property>    </bean></beans>