hitcounterfilter.java

来自「卡内基梅隆大学软件工程课件,很全面」· Java 代码 · 共 79 行

/*
 *
 * Copyright 2001 Sun Microsystems, Inc. All Rights Reserved.
 * 
 * This software is the proprietary information of Sun Microsystems, Inc.  
 * Use is subject to license terms.
 * 
 */

package filters;

import java.io.*;
import java.sql.Timestamp;
import java.util.*;
import javax.servlet.*;
import javax.servlet.http.*;
import util.Counter;

public final class HitCounterFilter implements Filter {
    private FilterConfig filterConfig = null;

    public void init(FilterConfig filterConfig) throws ServletException {
        this.filterConfig = filterConfig;
    }
    
    public void destroy() {
        this.filterConfig = null;
    }
 
    public void doFilter(ServletRequest request, ServletResponse response,
      FilterChain chain) throws IOException, ServletException {

      if (filterConfig == null)
        return;

      HttpServletRequest hr = (HttpServletRequest)request;
      HttpSession session = hr.getSession();
      ResourceBundle messages = (ResourceBundle)session.getAttribute("messages");
      if (messages == null) {
         Locale locale=request.getLocale();
         messages = ResourceBundle.getBundle("messages.BookstoreMessages", locale); 
         session.setAttribute("messages", messages);
      }
      StringWriter sw = new StringWriter();
      PrintWriter writer = new PrintWriter(sw);

      Counter counter = (Counter)filterConfig.getServletContext().getAttribute("hitCounter");
      writer.println();
      writer.println("=======================================================");
      writer.println("The number of hits is: " + counter.incCounter());
      writer.println("=======================================================");

      // Log the resulting string
      writer.flush();
      filterConfig.getServletContext().log(sw.getBuffer().toString());

      PrintWriter out = response.getWriter();
      CharResponseWrapper wrapper = new CharResponseWrapper((HttpServletResponse)response); 
      chain.doFilter(request, wrapper);
      CharArrayWriter caw = new CharArrayWriter();
      caw.write(wrapper.toString().substring(0, wrapper.toString().indexOf("</body>")-1));
      caw.write("<p>\n<center>" + messages.getString("Visitor") + "<font color='red'>" + counter.getCounter() + "</font></center>");
      caw.write("\n</body></html>");
      response.setContentLength(caw.toString().length());
      out.write(caw.toString());        
      out.close();
    }

    public String toString() {
      if (filterConfig == null)  
        return ("HitCounterFilter()");
      StringBuffer sb = new StringBuffer("HitCounterFilter(");
      sb.append(filterConfig);
      sb.append(")");
      return (sb.toString());
    }
}