loginAction 中如何查询数据库里面数据

Question

SSHstruts2数据库

Answer 1

报什么异常了？你应该将UserInfoDAO定义为接口，然后用UserInfoDAOImpl实现该接口，注入的时候，注入实现类。

Answer 2

我就只想做个简单的登录功能
现在可以确定是Userinfo userinfo = userDao.findById(4);// 获取数据库里面的数据这句代码有问题
但不知道为什么这句代码没用，一运行到这客户端得到的就是500

Answer 3

把异常信息和UserinfoDAO代码贴出来。

Answer 4

type Exception reportmessagedescription The server encountered an internal error () that prevented it from fulfilling this request.exceptionjava.lang.NullPointerException
com.csw.action.LoginAction.login(LoginAction.java:40)
sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
java.lang.reflect.Method.invoke(Method.java:597)
com.opensymphony.xwork2.DefaultActionInvocation.invokeAction(DefaultActionInvocation.java:441)
com.opensymphony.xwork2.DefaultActionInvocation.invokeActionOnly(DefaultActionInvocation.java:280)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:243)
com.opensymphony.xwork2.interceptor.DefaultWorkflowInterceptor.doIntercept(DefaultWorkflowInterceptor.java:165)
com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:87)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
com.opensymphony.xwork2.validator.ValidationInterceptor.doIntercept(ValidationInterceptor.java:252)
org.apache.struts2.interceptor.validation.AnnotationValidationInterceptor.doIntercept(AnnotationValidationInterceptor.java:68)
com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:87)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
com.opensymphony.xwork2.interceptor.ConversionErrorInterceptor.intercept(ConversionErrorInterceptor.java:122)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
com.opensymphony.xwork2.interceptor.ParametersInterceptor.doIntercept(ParametersInterceptor.java:195)
com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:87)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
com.opensymphony.xwork2.interceptor.ParametersInterceptor.doIntercept(ParametersInterceptor.java:195)
com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:87)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
com.opensymphony.xwork2.interceptor.StaticParametersInterceptor.intercept(StaticParametersInterceptor.java:179)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
org.apache.struts2.interceptor.MultiselectInterceptor.intercept(MultiselectInterceptor.java:75)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
org.apache.struts2.interceptor.CheckboxInterceptor.intercept(CheckboxInterceptor.java:94)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
org.apache.struts2.interceptor.FileUploadInterceptor.intercept(FileUploadInterceptor.java:235)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
com.opensymphony.xwork2.interceptor.ModelDrivenInterceptor.intercept(ModelDrivenInterceptor.java:89)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
com.opensymphony.xwork2.interceptor.ScopedModelDrivenInterceptor.intercept(ScopedModelDrivenInterceptor.java:130)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
org.apache.struts2.interceptor.debugging.DebuggingInterceptor.intercept(DebuggingInterceptor.java:267)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
com.opensymphony.xwork2.interceptor.ChainingInterceptor.intercept(ChainingInterceptor.java:126)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
com.opensymphony.xwork2.interceptor.PrepareInterceptor.doIntercept(PrepareInterceptor.java:138)
com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:87)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
com.opensymphony.xwork2.interceptor.I18nInterceptor.intercept(I18nInterceptor.java:165)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
org.apache.struts2.interceptor.ServletConfigInterceptor.intercept(ServletConfigInterceptor.java:164)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
com.opensymphony.xwork2.interceptor.AliasInterceptor.intercept(AliasInterceptor.java:179)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
com.opensymphony.xwork2.interceptor.ExceptionMappingInterceptor.intercept(ExceptionMappingInterceptor.java:176)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
org.apache.struts2.impl.StrutsActionProxy.execute(StrutsActionProxy.java:52)
org.apache.struts2.dispatcher.Dispatcher.serviceAction(Dispatcher.java:488)
org.apache.struts2.dispatcher.ng.ExecuteOperations.executeAction(ExecuteOperations.java:77)
org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter.doFilter(StrutsPrepareAndExecuteFilter.java:91)
note The full stack trace of the root cause is available in the Apache Tomcat/6.0.14 logs.

Answer 5

我代码顺序改动了，就是这句空指针  Userinfo userinfo = userDao.findById(4);// 获取数据库里面的数据

Answer 6

UserinfoDAO代码package com.csw.entity;import java.util.List;
import org.hibernate.LockMode;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.context.ApplicationContext;
import org.springframework.orm.hibernate3.support.HibernateDaoSupport;/**
 * A data access object (DAO) providing persistence and search support for
 * Userinfo entities. Transaction control of the save(), update() and delete()
 * operations can directly support Spring container-managed transactions or they
 * can be augmented to handle user-managed Spring transactions. Each of these
 * methods provides additional information for how to configure it for the
 * desired type of transaction control.
 * 
 * @see com.csw.entity.Userinfo
 * @author MyEclipse Persistence Tools
 */public class UserinfoDAO extends HibernateDaoSupport {
private static final Logger log = LoggerFactory
.getLogger(UserinfoDAO.class);
// property constants
public static final String USERNAME = "username";
public static final String PASSWORD = "password";
public static final String EMAIL = "email"; protected void initDao() {
// do nothing
} public void save(Userinfo transientInstance) {
log.debug("saving Userinfo instance");
try {
getHibernateTemplate().save(transientInstance);
log.debug("save successful");
} catch (RuntimeException re) {
log.error("save failed", re);
throw re;
}
} public void delete(Userinfo persistentInstance) {
log.debug("deleting Userinfo instance");
try {
getHibernateTemplate().delete(persistentInstance);
log.debug("delete successful");
} catch (RuntimeException re) {
log.error("delete failed", re);
throw re;
}
} public Userinfo findById(java.lang.Integer id) {
log.debug("getting Userinfo instance with id: " + id);
try {
Userinfo instance = (Userinfo) getHibernateTemplate().get(
"com.csw.entity.Userinfo", id);
return instance;
} catch (RuntimeException re) {
log.error("get failed", re);
throw re;
}
} public List findByExample(Userinfo instance) {
log.debug("finding Userinfo instance by example");
try {
List results = getHibernateTemplate().findByExample(instance);
log.debug("find by example successful, result size: "
+ results.size());
return results;
} catch (RuntimeException re) {
log.error("find by example failed", re);
throw re;
}
} public List findByProperty(String propertyName, Object value) {
log.debug("finding Userinfo instance with property: " + propertyName
+ ", value: " + value);
try {
String queryString = "from Userinfo as model where model."
+ propertyName + "= ?";
return getHibernateTemplate().find(queryString, value);
} catch (RuntimeException re) {
log.error("find by property name failed", re);
throw re;
}
} public List findByUsername(Object username) {
return findByProperty(USERNAME, username);
} public List findByPassword(Object password) {
return findByProperty(PASSWORD, password);
} public List findByEmail(Object email) {
return findByProperty(EMAIL, email);
} public List findAll() {
log.debug("finding all Userinfo instances");
try {
String queryString = "from Userinfo";
return getHibernateTemplate().find(queryString);
} catch (RuntimeException re) {
log.error("find all failed", re);
throw re;
}
} public Userinfo merge(Userinfo detachedInstance) {
log.debug("merging Userinfo instance");
try {
Userinfo result = (Userinfo) getHibernateTemplate().merge(
detachedInstance);
log.debug("merge successful");
return result;
} catch (RuntimeException re) {
log.error("merge failed", re);
throw re;
}
} public void attachDirty(Userinfo instance) {
log.debug("attaching dirty Userinfo instance");
try {
getHibernateTemplate().saveOrUpdate(instance);
log.debug("attach successful");
} catch (RuntimeException re) {
log.error("attach failed", re);
throw re;
}
} public void attachClean(Userinfo instance) {
log.debug("attaching clean Userinfo instance");
try {
getHibernateTemplate().lock(instance, LockMode.NONE);
log.debug("attach successful");
} catch (RuntimeException re) {
log.error("attach failed", re);
throw re;
}
} public static UserinfoDAO getFromApplicationContext(ApplicationContext ctx) {
return (UserinfoDAO) ctx.getBean("UserinfoDAO");
}
}

Answer 7

下面是我struts.xml配置文件
<constant name="struts.objectFactory" value="spring" />
<package name="login" extends="json-default">
<action name="loginAction" class="com.csw.action.LoginAction"
method="login">
<result type="json">
<param name="includeProperties">

</param>
</result>
</action>
</package>应该算是交给spring管理了吧

Answer 8

 交给spring管理了，这里应该这样配置<action name="loginAction" class="loginAction"指向spring的bean啊