Example: com.ibm.websphere.LoggingFilter.java

The following example shows how to implement a filter...

package com.ibm.websphere;

import java.io.*;
import javax.servlet.*;

public class LoggingFilter implements Filter 
{
    File _loggingFile = null;

    // implement the required init method
    public void init(FilterConfig fc)
    {
        // create the logging file
        xxx;
    }

    // implement the required doFilter method...this is where most of 
            the work is done
    public void doFilter(ServletRequest request, 
                    ServletResponse response, FilterChain chain)
    {
        try
        {
            // add request info to the log file
            synchronized(_loggingFile)
            {
                xxx;
            }
 
            // pass the request on to the next resource in the chain
            chain.doFilter(request, response);
        }
        catch  Throwable(t)
        {
            // handle problem...
        }
    }

    // implement the required destroy method
    public void destroy()
    {
        // make sure logging file is closed
        _loggingFile.close();
    }
}

 

See Also

Servlet filtering
Filter, FilterChain, FilterConfig classes for servlet filtering
Webapplications: Resources for learning

 

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