import java.io.*;
import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import java.util.Enumeration;

public class UpperCaseFilter implements Filter {
  private FilterConfig filterConfig = null;
  public void destroy() {
    System.out.println("Filter destroyed");
    this.filterConfig = null;
  }
  
  public void doFilter(ServletRequest request, ServletResponse response,
    FilterChain chain)
    throws IOException, ServletException {
    System.out.println("Filter");
    Enumeration enum = request.getAttributeNames();
    while (enum.hasMoreElements()) {
      String attributeName = (String) enum.nextElement();
      String attributeValue = (String) request.getAttribute(attributeName);
      request.setAttribute(attributeName, attributeValue.toUpperCase());
    }
    
    chain.doFilter(request, response);
  }

  public void init(FilterConfig filterConfig) throws ServletException {
    System.out.println("Filter initialized");
    this.filterConfig = filterConfig;
  }
}