genericfilter.java

icsamples目录中有icsamples网络程序。 这个程序包括J2EE网络层的范例程序

package jwadbook.filter;

import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import java.io.FileOutputStream;

/**
 *
 * @author Jian (James) Cai
 */


public class GenericFilter implements javax.servlet.Filter {


	 private boolean logToFile = true;
	 private String logFileName = "../logs/filtertest.out";
	 private FileOutputStream logFileOut=null;


    /** Creates new GenericFilter */
    private FilterConfig filterConfig;
    
    public GenericFilter () {
    }

    public void doFilter(final ServletRequest request,final ServletResponse response,FilterChain chain) throws java.io.IOException, javax.servlet.ServletException 
    {
      chain.doFilter(request, response);
    }
    
    public void init(final FilterConfig filterConfig) 
    {
      this.filterConfig=filterConfig;

    }

    public void destroy()
    {

    }

    /***********************************************************
     * Log a message to the servlet context application log.
     *
     * @param message Message to be logged
     **********************************************************/

    protected void log(String message) {

	try
	    {
		if ( logToFile==true )
		    {
			if ( logFileOut == null )
			    {
				logFileOut = new FileOutputStream( logFileName, true );
			    }
			  
			logFileOut.write( ("Filter Test: " + message).getBytes());
			logFileOut.write ( "\n".getBytes());
		    }

		System.out.println("Filter Test: " + message);

	    }
		catch (Exception e )
		{
			System.out.println("Exception occured : " + e );
		}
    }


    /*******************************************************************
     * Log a message and associated exception to the servlet context
     * application log.
     *
     * @param message Message to be logged
     * @param throwable Exception to be logged
     ******************************************************************/

    protected void log(String message, Throwable throwable) {
		
	try
	    {
		if ( logToFile==true )
		    {
			if ( logFileOut == null )
			      {
				  logFileOut = new FileOutputStream( logFileName );
			      }
			  
			logFileOut.write( ("Filter Test: " + message).getBytes() );
			logFileOut.write ( "\n".getBytes() );
		    }
		System.out.println("Filter Test: system out !!!! " + message);
		throwable.printStackTrace(System.out);
	    }
	catch (Exception e )
	    {
		System.out.println("Exception occured : " + e );
	    }

    }    

} //end of GenericFilter