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filter以及filter的web.xml的配置

2013-03-27 20:29 281 查看

package filter;

import java.io.IOException;

import java.io.PrintWriter;

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;

public class filter implements Filter

{

   private FilterConfig config = null;

   private String blackList = null;

   public void init(FilterConfig config) throws ServletException

   {

       this.config = config;

       blackList = config.getInitParameter("blacklist");

   }

   public void destroy()

   {

       config = null;

   }

   public void doFilter(ServletRequest request, ServletResponse response,

           FilterChain chain) throws IOException, ServletException

   {

       String username = ((HttpServletRequest) request)

               .getParameter("username");

       if (username != null)

           username = new String(username.getBytes("utf-8"), "GB2312");

       if (username != null && username.indexOf(blackList) != -1)

       {

           response.setContentType("text/html;charset=GB2312");

           PrintWriter out = response.getWriter();

           out.println("<html><head></head><body>");

           out.println("<h1>对不起," + username + ",你没有权限留言 </h1>");

           out.println("</body></html>");

           out.flush();

           return;

       }

       /**

       * filter 的设置

       */

       long before = System.currentTimeMillis();

       config.getServletContext().log(

               "NoteFilter:before call chain.doFilter()");



       chain.doFilter(request, response);



       config.getServletContext()

               .log("NoteFilter:after call chain.doFilter()");

       long after = System.currentTimeMillis();

       String name = "";

       if (request instanceof HttpServletRequest)

       {

           name = ((HttpServletRequest) request).getRequestURI();

       }

       config.getServletContext().log(

               "NoteFilter:" + name + ": " + (after - before) + "ms");

   }
}

//web.xml的配置

<filter>

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

   <filter-class>filter.filter</filter-class>

   <init-param>

       <param-name>blacklist</param-name>

       <param-value>hello</param-value>

   </init-param>

</filter>

<filter-mapping>

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

   <url-pattern>/NoteServlet</url-pattern>

</filter-mapping>

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