<求助>java.lang.NullPointerException

avrilvv521 2012-04-25 09:36:47

错误页面：

Struts Problem Report
Struts has detected an unhandled exception:

Messages:
File: willow/business/code/action/CodeAction.java
Line number: 28

--------------------------------------------------------------------------------

Stacktraces
java.lang.NullPointerException
willow.business.code.action.CodeAction.execute(CodeAction.java:28)
sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
java.lang.reflect.Method.invoke(Unknown Source)
com.opensymphony.xwork2.DefaultActionInvocation.invokeAction(DefaultActionInvocation.java:453)
com.opensymphony.xwork2.DefaultActionInvocation.invokeActionOnly(DefaultActionInvocation.java:292)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:255)
org.apache.struts2.interceptor.debugging.DebuggingInterceptor.intercept(DebuggingInterceptor.java:256)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249)
com.opensymphony.xwork2.interceptor.DefaultWorkflowInterceptor.doIntercept(DefaultWorkflowInterceptor.java:176)
com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249)
com.opensymphony.xwork2.validator.ValidationInterceptor.doIntercept(ValidationInterceptor.java:265)
org.apache.struts2.interceptor.validation.AnnotationValidationInterceptor.doIntercept(AnnotationValidationInterceptor.java:68)
com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249)
com.opensymphony.xwork2.interceptor.ConversionErrorInterceptor.intercept(ConversionErrorInterceptor.java:138)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249)
com.opensymphony.xwork2.interceptor.ParametersInterceptor.doIntercept(ParametersInterceptor.java:211)
com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249)
com.opensymphony.xwork2.interceptor.ParametersInterceptor.doIntercept(ParametersInterceptor.java:211)
com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249)
com.opensymphony.xwork2.interceptor.StaticParametersInterceptor.intercept
。。。。省略
相关代码：

package willow.business.code.action;



import java.util.List;



import org.apache.log4j.Logger;

import org.springframework.beans.factory.BeanFactory;



import willow.business.code.CodeForm;

import willow.data.code.ICodeData;

import willow.entity.code.Code;



/**

 * Filename: CodeAction.java

 */

public class CodeAction extends CodeForm {



	private static final long serialVersionUID = 5371213145339553692L;

	static Logger logger = Logger.getLogger(CodeAction.class);

	

	public String execute() throws Exception {

		String input = INPUT;



		CodeForm cf = new CodeForm();

		cf.setCode(getCode());

		cf.setUpid(getUpid());



		BeanFactory bf = (BeanFactory)getBeanFactory();

		ICodeData cd = (ICodeData)bf.getBean("codedata");

		List<Code> list = cd.getCodes(bf,null,cf);

		logger.info(list.size());

		getRequest().setAttribute("list", list);

		input = SUCCESS;

		return input;

	}

}

applicationContext.xml 配置

<?xml version="1.0" encoding="UTF-8"?>

<!-- Filename: applicationContext.xml -->

<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-2.5.xsd">



  <bean id="sessionFactory" class="org.springframework.orm.hibernate4.LocalSessionFactoryBean">

    <property name="configLocation" value="classpath:hibernate.cfg.xml"></property>

    <property name="hibernateProperties">

      <props>

        <prop key="hibernate.connection.autocommit">true</prop>

      </props>

    </property>

  </bean>



  <bean id="codedao" class="willow.dao.hibernate.code.CodeDao">

    <property name="sessionFactory">

      <ref bean="sessionFactory" />

    </property>

  </bean>

  <bean id="codedata" class="willow.data.hibernate.code.CodeData"></bean>



  <bean id="appraisedao" class="willow.dao.hibernate.science.AppraiseDao">

    <property name="sessionFactory">

      <ref bean="sessionFactory" />

    </property>

  </bean>

  <bean id="appraisedata" class="willow.data.hibernate.science.AppraiseData"></bean>





  <!-- Define IoC beans 

  <bean id="dao" class="willow.dao.c3p0.C3p0Dao"></bean>

-->

  <!-- Define AOP advice 

  <bean id="daoInterceptor" class="willow.data.advice.DaoInterceptor"></bean>

-->

  <!-- Define AOP target 

  <bean id="studentdata-target" class="willow.data.mysql.StudentData"></bean>

-->

  <!-- Define AOP proxy factory bean, invocation bean 

  <bean id="studentdata" class="org.springframework.aop.framework.ProxyFactoryBean">

    <property name="proxyInterfaces">

      <value>willow.data.mysql.IStudentData</value>

    </property>

    <property name="interceptorNames">

      <list>

        <value>daoInterceptor</value>  

      </list>

    </property>

    <property name="target">

      <ref bean="studentdata-target"/>

    </property>

  </bean>



-->



  <!--                     Hibernate                

 -->

</beans>