神马空指针的，晕！！

Question

想做一个简单的登录验证，结果不停的报空指针错误，郁闷呐！！向各位求助一下！！
报错如下
严重: Servlet.service() for servlet action threw exception
java.lang.NullPointerException
at com.yourcompany.struts.action.CheckAction.execute(CheckAction.java:58)
at org.apache.struts.action.RequestProcessor.processActionPerform(RequestProcessor.java:431)
at org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:236)
at org.apache.struts.action.ActionServlet.process(ActionServlet.java:1196)
at org.apache.struts.action.ActionServlet.doGet(ActionServlet.java:414)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:617)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:128)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:293)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:849)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:583)
at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:454)
at java.lang.Thread.run(Thread.java:619)各位靠你们了！！

Answer 1

用的是struts1+spring+hibernate 

Answer 2

CheckAction.java:58这行附近的代码都发出来瞧瞧

Answer 3

这是checkAction
public ActionForward execute(ActionMapping mapping, ActionForm form,
HttpServletRequest request, HttpServletResponse response) {
// TODO Auto-generated method stub

CheckForm check=(CheckForm) form;

Users user=userbiz.findByUserNameAndPassWord(check.getUser().getUserName(), check.getUser().getPassWord());

if (user!=null) {
return mapping.findForward("show");
}else {
return mapping.findForward("error");
}

Answer 4

58行是哪一行？
在 Users user=userbiz.findByUserNameAndPassWord(check.getUser().getUserName(), check.getUser().getPassWord());这一句之前
Sysout一下userbiz，这玩意在哪初始化的

Answer 5

userbiz和form都可能为空，只能自己打断点调试一下了。

Answer 6

不好意思 Users user=userbiz.findByUserNameAndPassWord(check.getUser().getUserName(), check.getUser().getPassWord());这一行就是58行
userbiz我在checkAction中 做成了私有属性 生成了get set方法的！！

Answer 7

请问楼主有没在spring里面注入userbiz呢？

Answer 8

貌似在这个action的bean定义里面注入一下userbiz就不会出现这个问题了。

Answer 9

注入了 
<bean id="UsersBIZ" class="struts1.test1.biz.UsersBIZImpl"></bean>
这样没问题吧！！

Answer 10

加上这个
<bean id="*Action" class="*">
<property name="userbiz" ref="UsersBIZ" />
</bean>

Answer 11

我写的这段是指，在你这个action的bean定义里面 加上 
<property name="userbiz" ref="UsersBIZ" />
就行的。

Answer 12

比如：
<bean id="bwfReviewCheckInfoAction" scope="prototype" 
class="com.eshore.itsm.billing.processMonitor.web.action.BwfReviewCheckInfoAction">
<property name="bwfReviewCheckInfoService" ref="bwfReviewCheckInfoService" />
</bean><bean id="bwfReviewCheckInfoService" 
class="com.eshore.itsm.billing.processMonitor.service.impl.BwfReviewCheckInfoServiceImpl">
<property name="publicTableDAO" ref="publicTableDAO" /> 
</bean>

Answer 13

现在报这错 
严重: Servlet.service() for servlet action threw exception
java.lang.NullPointerException
at struts1.test1.biz.UsersBIZImpl.findByUserNameAndPassWord(UsersBIZImpl.java:79)
at com.yourcompany.struts.action.CheckAction.execute(CheckAction.java:61)
at org.apache.struts.action.RequestProcessor.processActionPerform(RequestProcessor.java:431)
at org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:236)
at org.apache.struts.action.ActionServlet.process(ActionServlet.java:1196)
at org.apache.struts.action.ActionServlet.doGet(ActionServlet.java:414)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:617)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:128)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:293)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:849)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:583)
at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:454)
at java.lang.Thread.run(Thread.java:619)

Answer 14

UsersBIZImpl.java:79 return userdao.findByUserNameAndPassWord(userName, password);CheckAction.java:61Users user=userbiz.findByUserNameAndPassWord(check.getUser().getUserName(), check.getUser().getPassWord());

Answer 15

很明显，已经不是userbiz为null那个错误了，楼主检查下UsersBIZImpl.java 79行，看下什么问题

Answer 16

怀疑是同样的错误，应该是userdao没有注入到userbiz里面

Answer 17

我也是刚想到这个问题试了一下 不报空指针了 又抱这错了严重: Servlet.service() for servlet action threw exception
org.hibernate.hql.ast.QuerySyntaxException: unexpected token: * near line 1, column 8 [select * from users where username='admin' and password='123']
at org.hibernate.hql.ast.QuerySyntaxException.convert(QuerySyntaxException.java:54)
at org.hibernate.hql.ast.QuerySyntaxException.convert(QuerySyntaxException.java:47)
at org.hibernate.hql.ast.ErrorCounter.throwQueryException(ErrorCounter.java:82)
at org.hibernate.hql.ast.QueryTranslatorImpl.parse(QueryTranslatorImpl.java:284)
at org.hibernate.hql.ast.QueryTranslatorImpl.doCompile(QueryTranslatorImpl.java:182)
at org.hibernate.hql.ast.QueryTranslatorImpl.compile(QueryTranslatorImpl.java:136)
at org.hibernate.engine.query.HQLQueryPlan.<init>(HQLQueryPlan.java:101)
at org.hibernate.engine.query.HQLQueryPlan.<init>(HQLQueryPlan.java:80)
at org.hibernate.engine.query.QueryPlanCache.getHQLQueryPlan(QueryPlanCache.java:94)
at org.hibernate.impl.AbstractSessionImpl.getHQLQueryPlan(AbstractSessionImpl.java:156)
at org.hibernate.impl.AbstractSessionImpl.createQuery(AbstractSessionImpl.java:135)
at org.hibernate.impl.SessionImpl.createQuery(SessionImpl.java:1651)
at struts1.test1.dao.UsersDAOImpl.findByUserNameAndPassWord(UsersDAOImpl.java:191)
at struts1.test1.biz.UsersBIZImpl.findByUserNameAndPassWord(UsersBIZImpl.java:79)
at com.yourcompany.struts.action.CheckAction.execute(CheckAction.java:61)
at org.apache.struts.action.RequestProcessor.processActionPerform(RequestProcessor.java:431)
at org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:236)
at org.apache.struts.action.ActionServlet.process(ActionServlet.java:1196)
at org.apache.struts.action.ActionServlet.doGet(ActionServlet.java:414)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:617)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:128)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:293)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:849)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:583)
at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:454)
at java.lang.Thread.run(Thread.java:619)红色那一行为报错的行
String hql="select * from users where username='"+userName+"' and password='"+password+"'";
Session session=super.getSession();
Query query=session.createQuery(hql);
super.releaseSession(session);
return (Users)query.uniqueResult();

Answer 18

Query query=session.createQuery(hql);这行报错

Answer 19

作为userbiz的一个私有属性 并生成get set方法！

Answer 20

楼主是用的hibernate吗？  hibernate的hql好像不是这样写的哦？ 楼主还是先学习下hibernate吧。

Answer 21

哈哈 太悲剧了 我也发现了 语句有问题 呵呵 能不能给个hql例子 

Answer 22

lz,你让我想到了我刚学ssh框架的时候，也是丢三落四的！不是这里没注入，就是那里报错，呵呵！看了楼主还有很大的进升空间呀，加油啦！

Answer 23

额......................再麻烦大家一下  我改了hql语句 现在又抱这错
严重: Servlet.service() for servlet action threw exception
org.hibernate.hql.ast.QuerySyntaxException: users is not mapped [from users as u where u.userName='admin' and u.passWord='123']
at org.hibernate.hql.ast.util.SessionFactoryHelper.requireClassPersister(SessionFactoryHelper.java:181)
at org.hibernate.hql.ast.tree.FromElementFactory.addFromElement(FromElementFactory.java:110)
at org.hibernate.hql.ast.tree.FromClause.addFromElement(FromClause.java:94)
at org.hibernate.hql.ast.HqlSqlWalker.createFromElement(HqlSqlWalker.java:316)
at org.hibernate.hql.antlr.HqlSqlBaseWalker.fromElement(HqlSqlBaseWalker.java:3228)
at org.hibernate.hql.antlr.HqlSqlBaseWalker.fromElementList(HqlSqlBaseWalker.java:3112)
at org.hibernate.hql.antlr.HqlSqlBaseWalker.fromClause(HqlSqlBaseWalker.java:720)
at org.hibernate.hql.antlr.HqlSqlBaseWalker.query(HqlSqlBaseWalker.java:571)
at org.hibernate.hql.antlr.HqlSqlBaseWalker.selectStatement(HqlSqlBaseWalker.java:288)
at org.hibernate.hql.antlr.HqlSqlBaseWalker.statement(HqlSqlBaseWalker.java:231)
at org.hibernate.hql.ast.QueryTranslatorImpl.analyze(QueryTranslatorImpl.java:254)
at org.hibernate.hql.ast.QueryTranslatorImpl.doCompile(QueryTranslatorImpl.java:185)
at org.hibernate.hql.ast.QueryTranslatorImpl.compile(QueryTranslatorImpl.java:136)
at org.hibernate.engine.query.HQLQueryPlan.<init>(HQLQueryPlan.java:101)
at org.hibernate.engine.query.HQLQueryPlan.<init>(HQLQueryPlan.java:80)
at org.hibernate.engine.query.QueryPlanCache.getHQLQueryPlan(QueryPlanCache.java:94)
at org.hibernate.impl.AbstractSessionImpl.getHQLQueryPlan(AbstractSessionImpl.java:156)
at org.hibernate.impl.AbstractSessionImpl.createQuery(AbstractSessionImpl.java:135)
at org.hibernate.impl.SessionImpl.createQuery(SessionImpl.java:1651)
at struts1.test1.dao.UsersDAOImpl.findByUserNameAndPassWord(UsersDAOImpl.java:191)
at struts1.test1.biz.UsersBIZImpl.findByUserNameAndPassWord(UsersBIZImpl.java:79)
at com.yourcompany.struts.action.CheckAction.execute(CheckAction.java:61)
at org.apache.struts.action.RequestProcessor.processActionPerform(RequestProcessor.java:431)
at org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:236)
at org.apache.struts.action.ActionServlet.process(ActionServlet.java:1196)
at org.apache.struts.action.ActionServlet.doGet(ActionServlet.java:414)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:617)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:128)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:293)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:849)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:583)
at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:454)
at java.lang.Thread.run(Thread.java:619)

Answer 24

from 后面加的是java对象名，并非表名，楼主注意下。

Answer 25

恩 谢谢了 我已经解决完了 就是这个问题 十分感谢各位 哈哈 不过如果在applicationContext.xml文件头部加一个 default-autowire="byType" 就会自动注入了 哈哈 我没加就想玩儿自动 晕！！