Example 7.9 MultipartEncodeFilter - Standard Filter Strategy

public class MultipartEncodeFilter extends 
  BaseEncodeFilter {
  public MultipartEncodeFilter() { }
  public void doFilter(javax.servlet.ServletRequest 
    servletRequest, javax.servlet.ServletResponse 
    servletResponse,javax.servlet.FilterChain 
    filterChain)
  throws java.io.IOException, 
    javax.servlet.ServletException {
    String contentType = 
      servletRequest.getContentType();   
    // Only filter this request if it is multipart 
    // encoding                
    if (contentType.startsWith(
                "multipart/form-data")){
      try {
        String uploadFolder = 
          getFilterConfig().getInitParameter(
              "UploadFolder");
        if (uploadFolder == null) uploadFolder = ".";

        /** The MultipartRequest class is: 
        * Copyright (C) 2001 by Jason Hunter 
        * <jhunter@servlets.com>. All rights reserved. 
        **/
        MultipartRequest multi = new 
          MultipartRequest(servletRequest, 
                           uploadFolder,
                           1 * 1024 * 1024 );
        Enumeration params = 
	         multi.getParameterNames();
        while (params.hasMoreElements()) {
          String name = (String)params.nextElement();
          String value = multi.getParameter(name);
          servletRequest.setAttribute(name, value);
        }

        Enumeration files = multi.getFileNames();
        while (files.hasMoreElements()) {
          String name = (String)files.nextElement();
          String filename = multi.getFilesystemName(name);
          String type = multi.getContentType(name);
          File f = multi.getFile(name);
          // At this point, do something with the 
          // file, as necessary
        }
      }
      catch (IOException e)
      {
        LogManager.logMessage(
          "error reading or saving file"+ e);
      }
    } // end if
    filterChain.doFilter(servletRequest, 
                         servletResponse);
  } // end method doFilter()
}