struts2+Hibernian+spring集合时出现的问题

Question

这个是 DAO层的部分代码：
package com.dao;
import java.util.List;
import org.springframework.dao.DataAccessException;
import org.springframework.orm.hibernate3.support.HibernateDaoSupport;public class ObjectDao extends HibernateDaoSupport { // condition为条件，查询一组数据，该方法的返回类型为Object
public Object getObjectForm(String condition) {
List list = null;
Object object = null;
try {
list = getHibernateTemplate().find(condition);
if (list.size() == 1) {
object = (Object) list.get(0);
}
} catch (DataAccessException ex) {
ex.printStackTrace();
}
return object;
}
}Bean层的是ManagerFormaction的是
package com.action;
import com.bean.ManagerForm;
import com.dao.ObjectDao;
import com.opensymphony.xwork2.ActionContext;
import com.opensymphony.xwork2.ActionSupport;
public class ManagerAction extends ActionSupport {

private ManagerForm managerform;
private ObjectDao objectdao;

public ObjectDao getObjectdao() {
return objectdao;
}
public void setObjectdao(ObjectDao objectdao) {
this.objectdao = objectdao;
}
public ManagerForm getManagerform() {
return managerform;
}
public void setManagerform(ManagerForm managerform) {
this.managerform = managerform;
} public Object checkManager() throws Exception {

managerform=(ManagerForm)objectdao.getObjectForm("from ManagerForm where account='"+ managerform.getAccount() + "'");

if (managerform == null) {

ActionContext.getContext().getSession().put("errorNews", "您输入的账号不存在");


} else if (!managerform.getPassword().equals(managerform.getPassword())) {

ActionContext.getContext().getSession().put("errorNews", "您输入的密码不正确"); } else {

ActionContext.getContext().getSession().put("managerform", managerform);
}
return "checkManager";

}
}这是个登陆验证的..可是老是报java.lang.NullPointerException异常..为什么呢..
是不是DAO层不对...那位高手指点下哈..

Answer 1

异常栈是什么？？我把报的错贴下严重: Servlet.service() for servlet default threw exception
java.lang.NullPointerException
at com.action.ManagerAction.checkManager(ManagerAction.java:37)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at com.opensymphony.xwork2.DefaultActionInvocation.invokeAction(DefaultActionInvocation.java:404)
at com.opensymphony.xwork2.DefaultActionInvocation.invokeActionOnly(DefaultActionInvocation.java:267)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:229)
at com.opensymphony.xwork2.interceptor.DefaultWorkflowInterceptor.doIntercept(DefaultWorkflowInterceptor.java:221)
at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:86)
at com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:224)
at com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:223)
at com.opensymphony.xwork2.util.profiling.UtilTimerStack.profile(UtilTimerStack.java:455)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:221)
at com.opensymphony.xwork2.validator.ValidationInterceptor.doIntercept(ValidationInterceptor.java:150)
at org.apache.struts2.interceptor.validation.AnnotationValidationInterceptor.doIntercept(AnnotationValidationInterceptor.java:48)
at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:86)
at com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:224)
at com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:223)
at com.opensymphony.xwork2.util.profiling.UtilTimerStack.profile(UtilTimerStack.java:455)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:221)
at com.opensymphony.xwork2.interceptor.ConversionErrorInterceptor.intercept(ConversionErrorInterceptor.java:123)
at com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:224)
at com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:223)
at com.opensymphony.xwork2.util.profiling.UtilTimerStack.profile(UtilTimerStack.java:455)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:221)
at com.opensymphony.xwork2.interceptor.ParametersInterceptor.doIntercept(ParametersInterceptor.java:167)
at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:86)
at com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:224)
at com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:223)
at com.opensymphony.xwork2.util.profiling.UtilTimerStack.profile(UtilTimerStack.java:455)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:221)
at com.opensymphony.xwork2.interceptor.StaticParametersInterceptor.intercept(StaticParametersInterceptor.java:105)
at com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:224)
at com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:223)
at com.opensymphony.xwork2.util.profiling.UtilTimerStack.profile(UtilTimerStack.java:455)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:221)
at org.apache.struts2.interceptor.CheckboxInterceptor.intercept(CheckboxInterceptor.java:83)
at com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:224)
at com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:223)
at com.opensymphony.xwork2.util.profiling.UtilTimerStack.profile(UtilTimerStack.java:455)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:221)
at org.apache.struts2.interceptor.FileUploadInterceptor.intercept(FileUploadInterceptor.java:268)
at com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:224)
at com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:223)
at com.opensymphony.xwork2.util.profiling.UtilTimerStack.profile(UtilTimerStack.java:455)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:221)
at com.opensymphony.xwork2.interceptor.ModelDrivenInterceptor.intercept(ModelDrivenInterceptor.java:74)
at com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:224)
at com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:223)
at com.opensymphony.xwork2.util.profiling.UtilTimerStack.profile(UtilTimerStack.java:455)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:221)
at com.opensymphony.xwork2.interceptor.ScopedModelDrivenInterceptor.intercept(ScopedModelDrivenInterceptor.java:127)
at com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:224)
at com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:223)
at com.opensymphony.xwork2.util.profiling.UtilTimerStack.profile(UtilTimerStack.java:455)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:221)
at org.apache.struts2.interceptor.ProfilingActivationInterceptor.intercept(ProfilingActivationInterceptor.java:107)
at com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:224)
at com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:223)
at com.opensymphony.xwork2.util.profiling.UtilTimerStack.profile(UtilTimerStack.java:455)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:221)
at org.apache.struts2.interceptor.debugging.DebuggingInterceptor.intercept(DebuggingInterceptor.java:206)
at com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:224)
at com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:223)
at com.opensymphony.xwork2.util.profiling.UtilTimerStack.profile(UtilTimerStack.java:455)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:221)
at com.opensymphony.xwork2.interceptor.ChainingInterceptor.intercept(ChainingInterceptor.java:115)
at com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:224)
at com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:223)
at com.opensymphony.xwork2.util.profiling.UtilTimerStack.profile(UtilTimerStack.java:455)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:221)
at com.opensymphony.xwork2.interceptor.I18nInterceptor.intercept(I18nInterceptor.java:143)
at com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:224)
at com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:223)
at com.opensymphony.xwork2.util.profiling.UtilTimerStack.profile(UtilTimerStack.java:455)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:221)
at com.opensymphony.xwork2.interceptor.PrepareInterceptor.doIntercept(PrepareInterceptor.java:121)
at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:86)
at com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:224)
at com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:223)
at com.opensymphony.xwork2.util.profiling.UtilTimerStack.profile(UtilTimerStack.java:455)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:221)
at org.apache.struts2.interceptor.ServletConfigInterceptor.intercept(ServletConfigInterceptor.java:170)
at com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:224)
at com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:223)
at com.opensymphony.xwork2.util.profiling.UtilTimerStack.profile(UtilTimerStack.java:455)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:221)
at com.opensymphony.xwork2.interceptor.AliasInterceptor.intercept(AliasInterceptor.java:123)
at com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:224)
at com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:223)
at com.opensymphony.xwork2.util.profiling.UtilTimerStack.profile(UtilTimerStack.java:455)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:221)
at com.opensymphony.xwork2.interceptor.ExceptionMappingInterceptor.intercept(ExceptionMappingInterceptor.java:176)
at com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:224)
at com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:223)
at com.opensymphony.xwork2.util.profiling.UtilTimerStack.profile(UtilTimerStack.java:455)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:221)
at org.apache.struts2.impl.StrutsActionProxy.execute(StrutsActionProxy.java:50)

Answer 2

    // condition为条件，查询一组数据，该方法的返回类型为Object
    public Object getObjectForm(String condition) {
        List list = null;
        Object object = null;
        try {
            list = getHibernateTemplate().find(condition);
            if (list.size() == 1) {
                object = (Object) list.get(0);
            }
        } catch (DataAccessException ex) {
            ex.printStackTrace();
        }
        return object;
    }
可能是这里的问题。读取list的时做个NULL判定，或者直接修改list的定义为：List list = new ArrayList();试试！

Answer 3

果然是 改成 List list = new ArrayList();  为什么呢？？
郁闷..谢啦 3楼的..

Answer 4

list = getHibernateTemplate().find(condition);这段里面如果没有取到值，list的值就仍然是null，然后if (list.size() == 1) {
。这里便会报空指针错误。

Answer 5

原因就是5楼回答的！getHibernateTemplate().find(condition);如果。没有取到值的话，list仍然为null,这时候去调用list.size(),自然就会出错