Question

spring 注入 空指针怎么办？

我的applicationContext xml
<bean id="sessionFactory"
class="org.springframework.orm.hibernate3.LocalSessionFactoryBean">
<property name="configLocation"
value="classpath:hibernate.cfg.xml">
</property>
</bean>
<bean id="DButil" class="util.DButil">
<property name="sf">
<ref local="sessionFactory"/>
</property>
</bean>

servlet
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
request.setCharacterEncoding("GB18030");
response.setCharacterEncoding("GB18030");
HttpSession session=request.getSession();
Userbean userbean=(Userbean) session.getAttribute("userbean");
if(userbean==null){
userbean=new Userbean();
}
WebApplicationContext wac=WebApplicationContextUtils.getWebApplicationContext(this.getServletContext());
DButil db=(DButil) wac.getBean("DButil");
到最后一行的时候就报空指针！！

Answer 1

调试，看你哪个变量是null，不过我是觉得你的web.xml没写对

Answer 2

你的this.getServletContext() 怎么得到servletContext实例

Answer 3

wac没有获取到数据吧

Answer 4

空指针肯定是 wac为null了