hitcounterfilter.java

J2EE导学

/*
 *
 * 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.IOException;
import java.io.PrintWriter;
import java.io.StringWriter;
import java.sql.Timestamp;
import java.util.*;
import javax.servlet.*;
import javax.servlet.http.*;
import database.BookDetails;
import cart.*;
import java.util.*;
import util.Counter;

public final class HitCounterFilter implements Filter {
   private FilterConfig filterConfig = null;
   public void doFilter(ServletRequest request, ServletResponse response,
         FilterChain chain) throws IOException, ServletException {

         if (filterConfig == null)
            return;

         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);
         out.write(wrapper.getData());
         out.println("<center>You are visitor number <font color=\"red\">" + counter.getCounter() + "</font></center>");
    }

    public FilterConfig getFilterConfig() {
         return (this.filterConfig);
    }

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

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

    }
}