如何做登录后自动跳转到登录前要访问的页面

http://blog.csdn.net/zrwlc2008/archive/2007/07/19/1698981.aspx

import java.io.IOException;
import java.net.URLEncoder;

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.HttpServletResponse;

import com.ww.golf.bo.Player;
import com.ww.golf.util.ActionUtils;

public class LogFilter implements Filter {

    protected FilterConfig filterConfig;

    public void init(FilterConfig config) throws ServletException {
        this.filterConfig = config;
    }

    public void doFilter(ServletRequest srequest, ServletResponse sresponse,
            FilterChain chain) throws IOException, ServletException {
        HttpServletRequest request = (HttpServletRequest) srequest;
        HttpServletResponse response = (HttpServletResponse) sresponse;

        Player player = (Player) request.getSession().getAttribute(
                ActionUtils.PLAYER_OBJ_KEY);
        if (player == null) {
            StringBuffer sUrl = new StringBuffer("");
            if (request.getRequestURI() != null) {
                sUrl
                        .append(URLEncoder.encode(request.getRequestURI(),
                                "UTF-8"));
            }
            if (request.getQueryString() != null) {
                sUrl.append("?");
                sUrl.append(URLEncoder
                        .encode(request.getQueryString(), "UTF-8"));
            }

            System.out.println("URL:" + sUrl);
            response.sendRedirect("../index.jsp?" + ActionUtils.GO_URI_KEY
                    + "=" + sUrl.toString());
        } else {
            chain.doFilter(request, response);
        }

    }

    public void setFilterConfig(final FilterConfig filterConfig) {
        this.filterConfig = filterConfig;
    }

    public void destroy() {
        this.filterConfig = null;
    }
}

 

        再于应用的web.xml中配置这个Filter

<filter>
        <filter-name>logf</filter-name>
        <filter-class>com.ww.golf.filter.LogFilter</filter-class>

    </filter>
<filter-mapping>
        <filter-name>logf</filter-name>
        <url-pattern>/player/*</url-pattern>
    </filter-mapping>

   这个代码的功能就是说：当访问 localhost:8080 / test / player / 目录里的页面(假设是登陆后显示的所有页面), 会经过Filter , 然后验证session ， 如果未登陆或超时,，就回到登陆页面,，并把要访问的路径(比如 / player /  userinfo.jsp?id=111 ) 发到登陆页面， 登陆页面用一个hidden标签记录下来， 并同用户名和密码一起提交到struts的Action 。验证通过后， Action 就直接跳到访问路径userinfo.jsp 。

     写这个代码的时候，request.getRequestURI 只能获取不带参数的请求，如"userinfo.jsp?id=111"只能得到"userinfo.jsp" ，参数就丢了，等自动跳转了再执行是会报错的。后来查了一些文章才想起 request.getQueryString()就是用来获取请求中参数的。两者得一起用。哎，真是“基础不牢，越学越忘”。有功夫还得好好找点基础资料来看了。