Java struts2 中过滤器不好用

WEB.XML

authFilter
jp.cofesta.framework.web.filter.AuthorityFilter


encodingFilter
org.springframework.web.filter.CharacterEncodingFilter

encoding
UTF-8



struts2
org.apache.struts2.dispatcher.FilterDispatcher

<filter-mapping>
  <filter-name>authFilter</filter-name>
  <url-pattern>*.action</url-pattern>
</filter-mapping>

<filter-mapping>
  <filter-name>encodingFilter</filter-name>
  <url-pattern>*.*</url-pattern>
</filter-mapping>


<filter-mapping>
  <filter-name>struts2</filter-name>
  <url-pattern>*.action</url-pattern>
</filter-mapping>
<filter-mapping>
  <filter-name>struts2</filter-name>
  <url-pattern>*.jsp</url-pattern>
</filter-mapping>

过滤器 实现类

public class AuthorityFilter extends OncePerRequestFilter {

private String error = "/logout.action";

/**
 * error action setter method
 * 
 * @param error
 */
public void setError(String error) {
    this.error = error;
}

/**
 * filter
 * 
 * @param request
 * @param response
 * @param filterChain
 */
protected void doFilterInternal(HttpServletRequest request,
        HttpServletResponse response, FilterChain filterChain)
        throws IOException, ServletException {
    String requestURI = request.getRequestURI();
    //String shortRequestURI = requestURI.replace(request.getContextPath(),"");
    //ServletActionContext sac = new ServletActionContext(null,null);
    ServletActionContext.setRequest(request);
    User user = SecurityUtil.getLoginUser();
    if (requestURI.endsWith(error)) {
        filterChain.doFilter(request, response);
    }else if (user == null && !requestURI.endsWith(Constants.LOGINACTION)
            && !requestURI.endsWith(Constants.WELCOMEACTION)) {
        String forwardPath = request.getContextPath() + error;
        (new HttpServletResponseWrapper(response))
                .sendRedirect(forwardPath);
    } else {
        filterChain.doFilter(request, response);
    }
}

}

错误信息如下：

2010-8-25 13:34:56 org.apache.catalina.core.StandardWrapperValve invoke
严重: Servlet.service() for servlet default threw exception
java.lang.NullPointerException
at org.apache.struts2.ServletActionContext.setRequest(ServletActionContext.java:103)
at cc.yilian.invoicing.common.filter.AuthorityFilter.doFilterInternal(AuthorityFilter.java:51)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:75)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
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:127)
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:298)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:852)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:588)
at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489)
at java.lang.Thread.run(Unknown Source)

package com.xfaccp.filter;

import java.io.IOException;

import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpSession;

import com.xfaccp.bean.UserBean;

public class CheckLoginFilter implements Filter {

public void destroy() {
    // TODO Auto-generated method stub

}

public void doFilter(ServletRequest arg0, ServletResponse arg1,
        FilterChain arg2) throws IOException, ServletException {
    HttpServletRequest request = (HttpServletRequest)arg0;
    String url = request.getServletPath();
    HttpSession session = request.getSession();
    UserBean user = (UserBean)session.getAttribute("user");
    if(url.indexOf("LoginServlet") > 0)
    {
        arg2.doFilter(arg0, arg1);
    }
    else if(user == null || user.getId() < 1)
    {
        request.setAttribute("loginError", "请先登录！");
        request.getRequestDispatcher("/jsp/login.jsp").forward(arg0, arg1);
    }else
    {
        arg2.doFilter(arg0, arg1);
    }

}

public void init(FilterConfig arg0) throws ServletException {
    // TODO Auto-generated method stub

}

}

用Spring的过滤器
<!-- Filter 定义 -->
<!-- Character Encoding filter -->

encodingFilter
org.springframework.web.filter.CharacterEncodingFilter

encoding
UTF-8


forceEncoding
true

哦，自定义过滤器验证用户登录状态
一般处理是在登录过滤器中获取保存用户的session的用户当取不到用户时即NULL时跳转到登录页面
上面的错误是表示你的AuthorityFilter.java:51行有错误是一个NullPointerException 异常

你的代码有点晕，首先你是那什么来判断用户是否登录的，，都没看到页面传的参数。。。。

你的那个SecurityUtil放的是获取session的吧
建议使用
HttpServletRequest request = ServletActionContext.getRequest();
request.getSession().getAttribute("")的形式