FilterConfig关于权限过滤

Question

简单点儿的话，直接写到java里吧。
看我们的例子：
http://family168.com/tutorial/jsp/html/jsp-ch-07.html#jsp-ch-07-02

Answer 1

你可以在web.xml配置好filter的参数，然后通过filterconfig来读取init-param的值就可以了 
如下面的代码，/**
 * Copyright (c) 2007-2009 Ivan Lau, Gjun IT
 * 冬瓜网:  http://www.dongua.com
 * 巨匠IT： http://www.pcschoolchina.com
 * All rights reserved
 */
package com.gjun.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.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;import com.gjun.student.vo.Admin;/**
 * @author Administrator
 * 
 */
public class AuthFilter extends HttpServlet implements Filter { /*
 * (non-Javadoc)
 * 
 * @see javax.servlet.Filter#doFilter(javax.servlet.ServletRequest,
 *      javax.servlet.ServletResponse, javax.servlet.FilterChain)
 */
public void doFilter(ServletRequest request, ServletResponse response,
FilterChain filterChain) throws IOException, ServletException {
HttpServletRequest hRequest = (HttpServletRequest) request;
HttpServletResponse hResponse = (HttpServletResponse) response;
HttpSession session = hRequest.getSession();
                
                
if (hRequest.getRequestURI().indexOf("login") >= 0) {
filterChain.doFilter(request, response);
return;
}
Admin user = (Admin) session.getAttribute("user");
                //这段就是控制你的权限的地方，通过就直接派发的下一个filter
if (user!=null&&user.username.equals(role)) {
filterChain.doFilter(request, response);
} else {
hResponse.sendRedirect("login_input.action");
}
} private FilterConfig filterConfig;
        private String role;
        //这段应该
public void init(FilterConfig filterConfig) {
this.filterConfig = filterConfig;
                //从web.xml文件中读取role的值 
                this.role = filterConfig.getInitParameter("role");  }
}web.xml中的filter的参数的代码段<filter> 
   <filter-name>auth</filter-name> 
   <filter-class>com.gjun.filter.AuthFilter</filter-class> 
   <init-param> 
      <param-name>role</param-name> 
      <param-value>admin</param-value> 
   </init-param> 
</filter><filter-mapping> 
   <filter-name>auth</filter-name> 
   <url-pattern>/*</url-pattern> 
</filter-mapping>