Struts2拦截器的问题...

[zx44y]

一个SSH2的小项目..准备是配上拦截器的。
发现配上拦截器以后...进入Action就会报空指针错。

我以为是Spring的问题，但是是可以到达Action的，但是Service类会报空指针错。



下面是Struts2配置文件的代码：

<struts>
	<constant name="struts.objectFactory" value="org.apache.struts2.spring.StrutsSpringObjectFactory" />
	<constant name="struts.action.extension" value="do"/>  
	<constant name="struts.devMode" value="true" />  
     <package name="default" namespace="/" extends="struts-default">
	    <interceptors>
	            <interceptor name="LoginInterceptor" class="LoginInterceptor" />	
	            <interceptor-stack name="defaultInterceptor">
	                <interceptor-ref name="LoginInterceptor" />
	            </interceptor-stack>
	    </interceptors>
	    <!-- 定义默认拦截器 -->
	    <default-interceptor-ref name="LoginInterceptor" /> 
	    
		<!-- 定义全局处理结果 -->
        <global-results>
        	<!-- 逻辑名为login的结果，映射到/login.jsp页面 -->
        	<result name="login">/index.jsp</result>
        </global-results>
        
        <action name="login" class="UserAction" method="LoginCheck">
            <result name="success" type="redirectAction">write</result>
        </action>
        <action name="manage" class="ArticleAction" method="ArticleList">
            <result name="success" type="freemarker">/WEB-INF/ftl/manage.ftl</result>
        <action name="write" class="ArticleAction" method="ArticleWrite">
            <result name="success" type="freemarker">/WEB-INF/ftl/write.ftl</result>
        </action>
        </action>
</struts>

拦截器代码：

@Component("LoginInterceptor")
public class LoginInterceptor extends AbstractInterceptor {
	private static final long serialVersionUID = 1L;
	@Override
	public String intercept(ActionInvocation invocation) throws Exception {
        Map<String, Object> session = invocation.getInvocationContext().getSession();
        String LoginSign = (String) session.get("LoginSign");
        if (null != LoginSign && LoginSign.equals("Logined")) {
            System.out.println("拦截器：合法用户登录---");
            String result = invocation.invoke();
            return result;
        } else {
            System.out.println("拦截器：用户未登录---");
            return Action.LOGIN;
        }
	}
}

登录的代码：

@Controller("UserAction")
@Scope("prototype")
public class UserAction extends BaseAction{
	private static final long serialVersionUID = 1L;
	private UserService userService;
	public String LoginCheck(){
		Author author = new Author();
		author.setName(request.getParameter("username"));
		author.setPassword(request.getParameter("password"));
		if(userService.login(author)){
			session.put("LoginSign", "Logined");
			return SUCCESS;
		}else{
			return LOGIN;
		}
	}

登陆后的访问页面代码：

@Controller("ArticleAction")
@Scope("prototype")
public class ArticleAction extends BaseAction{
	private static final long serialVersionUID = 1L;
	private ArticleService articleService;
	private CategoryService categoryService;
	private String result;
	
	public String ArticleWrite() throws Exception {	
		List<Category> list = categoryService.findAll();
		request.setAttribute("clist", list);
		return SUCCESS;
    }

	@Resource(name="articleService")
	public void setArticleService(ArticleService articleService) {
		this.articleService = articleService;
	}
	
	@Resource(name="categoryService")
	public void setCategoryService(CategoryService categoryService) {
		this.categoryService = categoryService;
	}

	public String getResult() {
		return result;
	}

	public void setResult(String result) {
		this.result = result;
	}
}

[东方不败01]

struts.xml中 配置LoginInterceptor拦截器时，你在class属性里的拦截器包名写成包全名，就是加包前缀的试试？

[yanqun123]

已经直到action里面了，说明struts配置没有问题，空指针异常应该来自这里：

引用

@Resource(name="articleService") public void setArticleService(ArticleService articleService) { this.articleService = articleService; }

也就是说，你的这个注解没有生效，需要的对象没有注入“private ArticleService articleService;”成员， 导致你调用它的findAll方法时抛异常，你可以在代码里面打印一下这个articleService对象，看是否为空

[花谢尊前不敢香]

struts配置文件不完整，package没有结束标签

[sust2012]

配置拦截器时把默认的拦截器也加上 <struts> <package name="struts-parent" abstract="true" extends="struts-default,json-default"> <interceptors> <interceptor name="isUserLoginInterceptor" class="com.interceptor.IsUserLoginInterceptor"> </interceptor> <interceptor-stack name="parentDefaultStack"> <interceptor-ref name="isUserLoginInterceptor"></interceptor-ref> <interceptor-ref name="defaultStack"></interceptor-ref> </interceptor-stack> </interceptors> <default-interceptor-ref name="parentDefaultStack"></default-interceptor-ref> </package> </struts>

[雨中的看客]

应该是加载下面XML配置的时候“@Component("LoginInterceptor")”还没起作用。所以造成空指针。 <interceptors> <interceptor name="LoginInterceptor" class="LoginInterceptor" /> <interceptor-stack name="defaultInterceptor"> <interceptor-ref name="LoginInterceptor" /> </interceptor-stack> </interceptors> <!-- 定义默认拦截器 --> <default-interceptor-ref name="LoginInterceptor" />