小弟初学，遇到s2sh空指针异常，请高手指点

[wwwww112233]

报错如下

java.lang.NullPointerException
	p.controller.LoginAction.execute(LoginAction.java:41)
	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:452)
	com.opensymphony.xwork2.DefaultActionInvocation.invokeActionOnly(DefaultActionInvocation.java:291)
	com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:254)
	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:248)
	com.opensymphony.xwork2.validator.ValidationInterceptor.doIntercept(ValidationInterceptor.java:263)
	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:248)
	com.opensymphony.xwork2.interceptor.ConversionErrorInterceptor.intercept(ConversionErrorInterceptor.java:133)
	com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:248)
	com.opensymphony.xwork2.interceptor.ParametersInterceptor.doIntercept(ParametersInterceptor.java:207)
	com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)
	com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:248)
	com.opensymphony.xwork2.interceptor.ParametersInterceptor.doIntercept(ParametersInterceptor.java:207)
	com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)
	com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:248)
	com.opensymphony.xwork2.interceptor.StaticParametersInterceptor.intercept(StaticParametersInterceptor.java:190)
	com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:248)
	org.apache.struts2.interceptor.MultiselectInterceptor.intercept(MultiselectInterceptor.java:75)
	com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:248)
	org.apache.struts2.interceptor.CheckboxInterceptor.intercept(CheckboxInterceptor.java:94)
	com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:248)
	org.apache.struts2.interceptor.FileUploadInterceptor.intercept(FileUploadInterceptor.java:243)
	com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:248)
	com.opensymphony.xwork2.interceptor.ModelDrivenInterceptor.intercept(ModelDrivenInterceptor.java:100)
	com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:248)
	com.opensymphony.xwork2.interceptor.ScopedModelDrivenInterceptor.intercept(ScopedModelDrivenInterceptor.java:141)
	com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:248)
	org.apache.struts2.interceptor.debugging.DebuggingInterceptor.intercept(DebuggingInterceptor.java:267)
	com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:248)
	com.opensymphony.xwork2.interceptor.ChainingInterceptor.intercept(ChainingInterceptor.java:142)
	com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:248)
	com.opensymphony.xwork2.interceptor.PrepareInterceptor.doIntercept(PrepareInterceptor.java:166)
	com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)
	com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:248)
	com.opensymphony.xwork2.interceptor.I18nInterceptor.intercept(I18nInterceptor.java:176)
	com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:248)
	org.apache.struts2.interceptor.ServletConfigInterceptor.intercept(ServletConfigInterceptor.java:164)
	com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:248)
	com.opensymphony.xwork2.interceptor.AliasInterceptor.intercept(AliasInterceptor.java:190)
	com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:248)
	com.opensymphony.xwork2.interceptor.ExceptionMappingInterceptor.intercept(ExceptionMappingInterceptor.java:187)
	com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:248)
	org.apache.struts2.impl.StrutsActionProxy.execute(StrutsActionProxy.java:52)
	org.apache.struts2.dispatcher.Dispatcher.serviceAction(Dispatcher.java:485)
	org.apache.struts2.dispatcher.ng.ExecuteOperations.executeAction(ExecuteOperations.java:77)
	org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter.doFilter(StrutsPrepareAndExecuteFilter.java:91)

其中，我的LoginAction为：

public class LoginAction implements Action {

	private String userName;
	private String password;
	private IUserService userService;
	
	public String getUserName() {
	return userName;
	}

	public IUserService getUserService() {
		return userService;
	}

	public void setUserService(IUserService userService) {
		this.userService = userService;
	}

	public void setUserName(String userName) {
	this.userName = userName;
	}

	public String getPassword() {
	return password;
	}

	public void setPassword(String password) {
	this.password = password;
	}

	
	@Override
	public String execute() throws Exception {
		if(userService.IsValidUser(userName, password)){//就是这里userService为null！！			return SUCCESS;
			}else {
			return ERROR;
			}
	}

applicationContext.xml文件为：

<bean id="loginAction" class="p.controller.LoginAction"
		abstract="false" lazy-init="default" autowire="default">
		<property name="userService">
			<ref bean="UserService" />
		</property>
	</bean>
		<bean id="UserService" class="p.Service.Impl.UserService"
		abstract="false" lazy-init="default" autowire="default">
		<property name="userDAO">
			<ref bean="UserDAO" />
		</property>
	</bean>
	<bean id="UserDAO" class="p.dao.impl.UserDAO">
		<property name="sessionFactory">
			<ref bean="sessionFactory" />
		</property>

struts.xml为

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE struts PUBLIC "-//Apache Software Foundation//DTD Struts Configuration 2.1//EN" "http://struts.apache.org/dtds/struts-2.1.dtd">
<struts>

<constant name="struts.objectFactory" value="spring" /> 
<package name="main" extends="struts-default">
 <action name="login" class="p.controller.LoginAction">
<result name="success">/success.jsp</result>
<result name="error">/error.jsp</result>
</action>

</package>

</struts>  

小弟真是搞昏头了还是一直抛出空指针异常
我是用myeclipse 10,Apache Tomcat/6.0.13(这个是myeclipse 自带的那个),win 7
我在LoginAction.java上打了不少断点，启动Tomcat正常，当部署时，进入debug，这个时候我发现

public void setUserService(IUserService userService) {
		this.userService = userService;
	}

这段代码是正常的，而且此时userService是有值的，可是当部署完成，我进入login.jsp首页输入用户名以及密码，再运行的时候，发现LoginAction.java中账户以及密码值都能获取到，上面那段setUserService的代码也会执行，可是这时得到的userService永远是null，如何进入execut(）都就抛出最前面的null异常了。

求各位大哥帮忙看看，谢谢！！！！！

[lixiaomeng627]

struts.xml的配置文件里。把
<action name="login" class="p.controller.LoginAction">

改为
<action name="login" class="loginAction">

即struts.xml的class里的内容跟spring配置文件里的id一致。
改过之后你再试试

[gzqGyula]

应该是IUserService类没有实现注入吧！！

[guanzijuan123]

[Quote=引用 1 楼 的回复:]

struts.xml的配置文件里。把
<action name="login" class="p.controller.LoginAction">

改为
<action name="login" class="loginAction">

即struts.xml的class里的内容跟spring配置文件里的id一致。
改过之后你再试试
[/Quote]


正解，struts的xml和spring的xml中的action的name值是一样滴

[qiaowan19900712]

[Quote=引用 2 楼 的回复:]
应该是IUserService类没有实现注入吧！！
[/Quote]++注入接口

[那四年的誓言]

楼上正解

[wwwww112233]

[Quote=引用 1 楼 的回复:]
struts.xml的配置文件里。把
<action name="login" class="p.controller.LoginAction">

改为
<action name="login" class="loginAction">

即struts.xml的class里的内容跟spring配置文件里的id一致。
改过之后你再试试
[/Quote]

谢谢！按照你的修改解决了，取到值了，不过下一步就是执行IsValidUser(String username, String password)方法的时候又抛异常了。。。。。大哥能否在帮忙看下

	public boolean IsValidUser(String username, String password) {
		List users = userDAO.findByUserName(username);//debug发现就是这句导致的异常
		if (users == null || users.isEmpty()) {
			return false;
		}
		User user = (User) users.get(0);
		if (user.getPassword().equals(password)) {
		return true;
		} else {
		return false;
		}
		}

异常如下：

HTTP Status 500 -

type Exception report

message

description The server encountered an internal error () that prevented it from fulfilling this request.

exception

java.lang.reflect.InvocationTargetException
	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:452)
	com.opensymphony.xwork2.DefaultActionInvocation.invokeActionOnly(DefaultActionInvocation.java:291)
	com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:254)
	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:248)
	com.opensymphony.xwork2.validator.ValidationInterceptor.doIntercept(ValidationInterceptor.java:263)
	org.apache.struts2.interceptor.validation.AnnotationValidationInterceptor.doIntercept(AnnotationValidationInterceptor.java:68)
	.....
------
root cause

java.lang.NoSuchMethodError: antlr.collections.AST.getLine()I
	org.hibernate.hql.ast.HqlSqlWalker.generatePositionalParameter(HqlSqlWalker.java:896)
	org.hibernate.hql.antlr.HqlSqlBaseWalker.parameter(HqlSqlBaseWalker.java:4819)
	org.hibernate.hql.antlr.HqlSqlBaseWalker.expr(HqlSqlBaseWalker.java:1373)
	org.hibernate.hql.antlr.HqlSqlBaseWalker.exprOrSubquery(HqlSqlBaseWalker.java:4243)
	org.hibernate.hql.antlr.HqlSqlBaseWalker.comparisonExpr(HqlSqlBaseWalker.java:3725)
	org.hibernate.hql.antlr.HqlSqlBaseWalker.logicalExpr(HqlSqlBaseWalker.java:1864)
	org.hibernate.hql.antlr.HqlSqlBaseWalker.whereClause(HqlSqlBaseWalker.java:818)
	org.hibernate.hql.antlr.HqlSqlBaseWalker.query(HqlSqlBaseWalker.java:604)
	org.hibernate.hql.antlr.HqlSqlBaseWalker.selectStatement(HqlSqlBaseWalker.java:288)
	org.hibernate.hql.antlr.HqlSqlBaseWalker.statement(HqlSqlBaseWalker.java:231)
	org.hibernate.hql.ast.QueryTranslatorImpl.analyze(QueryTranslatorImpl.java:254)
	org.hibernate.hql.ast.QueryTranslatorImpl.doCompile(QueryTranslatorImpl.java:185)

我在网上查说是jar冲突，可我自己没有另外加jar包啊

谢谢！！！！

[坐观垂钓者]

NoSuchMethodError: antlr.collections.AST.getLine() 明显没有找到这个方法findByUserName啊

[Tommyzcg]

您配置的是UserService ，而在 action 调用的是 userService .
注意大小写啊。

[wwwww112233]

[Quote=引用 8 楼 的回复:]
NoSuchMethodError: antlr.collections.AST.getLine() 明显没有找到这个方法findByUserName啊
[/Quote]

	@Override
	public List findByUserName(Object userName) {
		return findByProperty(USER_NAME, userName);
	}

public List findByProperty(String propertyName, Object value) {
		log.debug("finding User instance with property: " + propertyName
				+ ", value: " + value);
		try {
			String queryString = "from User as model where model."
					+ propertyName + "= ?";
			return getHibernateTemplate().find(queryString, value);
		} catch (RuntimeException re) {
			log.error("find by property name failed", re);
			throw re;
		}
	}

谢谢，我发现上面的异常是执行findByUserName（）这个方法的时候，进入findByProperty（）的时候这个方法抛出的异常

String queryString = "from User as model where model."
					+ propertyName + "= ?";
			return getHibernateTemplate().find(queryString, value);

那句return出的异常。但这段代码是Hibernate自动生成的呀。这是为什么....

[wwwww112233]

我自己解决了，这下运行正常了。
前面是
<action name="login" class="p.controller.LoginAction">

改为
<action name="login" class="loginAction">


后面那个异常是JAR包的冲突 antlr2.7.2 与 antlr2.7.6 冲突
删除antlr2.7.2 即可。
谢谢！！