Web App struts框架里实现Filter.

1 web.xml里添加filter配置信息。

      <filter>

            <filter-name>Authentication</filter-name>

            <filter-class>

                  com.nova.colimas.web.filters.AuthenticationFilter

            </filter-class>

            <init-param>

                  <param-name>onError</param-name>

                  <param-value>/pages/index.jsp</param-value>

            </init-param>

      </filter>

      <filter-mapping>

            <filter-name>Authentication</filter-name>

            <url-pattern>/protect/*</url-pattern>

      </filter-mapping>

<filter-class>定义使用com.nova.colimas.web.filters.AuthenticationFilter类执行过滤Action。

<init-param>当验证失败后Forward到/pages/index.jsp

<filter-mapping>只有当地址包括/protect/时运行filter类

2 实现com.nova.colimas.web.filters.AuthenticationFilter

package com.nova.colimas.web.filters;

 

import java.io.IOException;

import javax.servlet.RequestDispatcher;

import javax.servlet.ServletException;

import javax.servlet.http.*;

import javax.servlet.Filter;

import javax.servlet.FilterChain;

import javax.servlet.FilterConfig;

 

import com.nova.colimas.web.bean.UserBean;

 

import javax.servlet.ServletRequest;

import javax.servlet.ServletResponse;

 

import org.apache.struts.Globals;

import org.apache.struts.action.*;

import com.nova.colimas.web.constants.Constants;

 

/**

 * Filter implementation for user authentication。必须实现Filter接口

 * @author tyrone

 * @version $Id: AuthenticationFilter.java,v 1.0

 */

public class AuthenticationFilter implements Filter

{

           

            /**

             * filterConfig will store the reference of FilterConfig

             */

            private FilterConfig filterConfig;

           

            private String onErrorUrl;

 

            /**

             * store the reference of the FilterConfig.

             * @param config FilterConfig object

             * @throws ServletException

             */

            public void init(FilterConfig config) throws ServletException

            {

//获得验证失败forward地址

                        filterConfig = config;

                        onErrorUrl=filterConfig.getInitParameter("onError");

                        if (onErrorUrl==null || "".equals(onErrorUrl)){

                                    onErrorUrl="/pages/index.jsp";

                        }

            }

            /**

             * User Authentication is  done. If User is authenticated successful then

             * control is transferred to logon URI

             * @param ServletRequest Request

             * @param ServletRequest Response

             * @param FilterChain Filter Chain

             * @throws ServletException,IOException

             */

            public void doFilter(ServletRequest request, ServletResponse response, FilterChain next)

                                    throws IOException, ServletException

            {

                        HttpServletRequest httpRequest = (HttpServletRequest)request;

                        HttpServletResponse httpResponse=(HttpServletResponse)response;

                        // Current session

                        HttpSession httpSession = httpRequest.getSession();

//Session里是否有用户信息。

                        if (httpSession.getAttribute(Constants.USER_KEY) == null)

                        {

                                    ActionErrors errors=new ActionErrors();

                                    errors.add(ActionErrors.GLOBAL_ERROR,

                                                            new ActionError("error authentication"));

                                    httpRequest.setAttribute(Globals.ERROR_KEY,errors);

                        //没有，验证失败forward到/pages/index.jsp            httpRequest.getRequestDispatcher(onErrorUrl).forward(httpRequest,httpResponse);

                        }else

//成果过滤Action结束

                                    next.doFilter(request,response);

                       

            }

 

            /**

             * destroy() method is called by the servlet container

             */

            public void destroy()

            {

            }

           

}