Filtro

Para poder vereficar el rol de administrador se utiliza el siguiente filtro:

package DAW;

import java.io.*;
import java.net.*;
import java.util.*;
import java.text.*;
import javax.servlet.*;
import javax.servlet.http.*;

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;

/**
 *
 * @author Daniel
 */
public class FiltroLogin implements Filter {

    // The filter configuration object we are associated with.  If
    // this value is null, this filter instance is not currently
    // configured.
    private FilterConfig filterConfig = null;

    public FiltroLogin() {
    }

    private void doBeforeProcessing(ServletRequest request, ServletResponse response)
 throws IOException, ServletException {
 if (debug) log(«FiltroLogin:DoBeforeProcessing»);
 //
 // Write code here to process the request and/or response before
 // the rest of the filter chain is invoked.
 //

 //
 // For example, a logging filter might log items on the request object,
 // such as the parameters.
 //
 /*
  for (Enumeration en = request.getParameterNames(); en.hasMoreElements(); ) {
      String name = (String)en.nextElement();
      String values[] = request.getParameterValues(name);
      int n = values.length;
      StringBuffer buf = new StringBuffer();
      buf.append(name);
      buf.append(«=»);
      for(int i=0; i < n; i++) {
          buf.append(values[i]);
          if (i < n-1)
              buf.append(«,»);
      }
      log(buf.toString());
  }
 */
 
    }

    private void doAfterProcessing(ServletRequest request, ServletResponse response) throws IOException, ServletException {
 if (debug) log(«FiltroLogin:DoAfterProcessing»);
 //
 // Write code here to process the request and/or response after
 // the rest of the filter chain is invoked.
 //
 
 //
 // For example, a logging filter might log the attributes on the
 // request object after the request has been processed.
 //
 /*
 for (Enumeration en = request.getAttributeNames(); en.hasMoreElements(); ) {
     String name = (String)en.nextElement();
     Object value = request.getAttribute(name);
     log(«attribute: » + name + «=» + value.toString());

 }
 */
 //

 //
 // For example, a filter might append something to the response.
 //
 /*
 PrintWriter respOut = new PrintWriter(response.getWriter());
 respOut.println(«<P><B>This has been appended by an intrusive filter.</B>»);
 */
    }

    /**
     *
     * @param request The servlet request we are processing
     * @param response The servlet response we are creating
     * @param chain The filter chain we are processing
     *
     * @exception IOException if an input/output error occurs
     * @exception ServletException if a servlet error occurs
     */
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {

 HttpServletResponse res=(HttpServletResponse)response;
       
        if (debug) log(«FiltroLogin:doFilter()»);

 doBeforeProcessing(request, response);
 
 Throwable problem = null;

 try {
    
            String user = request.getParameter(«usuario»);
            String pass = request.getParameter(«pasword»);
           
           if(user.equalsIgnoreCase(«estud») && pass.equalsIgnoreCase(«estud»)){

                chain.doFilter(request, response);
            }else
                res.sendError(401,»Su nombre de usuario» + user + » esta bloqueado para esta opcion, «);
           
 }
 catch(Throwable t) {
     //
     // If an exception is thrown somewhere down the filter chain,
     // we still want to execute our after processing, and then
     // rethrow the problem after that.
     //
     problem = t;
     t.printStackTrace();
 }

 doAfterProcessing(request, response);

 //
 // If there was a problem, we want to rethrow it if it is
 // a known type, otherwise log it.
 //
 if (problem != null) {
     if (problem instanceof ServletException) throw (ServletException)problem;
     if (problem instanceof IOException) throw (IOException)problem;
     sendProcessingError(problem, response);
 }
    }

   
    /**
     * Return the filter configuration object for this filter.
     */
    public FilterConfig getFilterConfig() {
 return (this.filterConfig);
    }
    /**
     * Set the filter configuration object for this filter.
     *
     * @param filterConfig The filter configuration object
     */
    public void setFilterConfig(FilterConfig filterConfig) {

 this.filterConfig = filterConfig;
    }

    /**
     * Destroy method for this filter
     *
     */
    public void destroy() {
    }
    /**
     * Init method for this filter
     *
     */
    public void init(FilterConfig filterConfig) {

 this.filterConfig = filterConfig;
 if (filterConfig != null) {
     if (debug) {
  log(«FiltroLogin:Initializing filter»);
     }
 }
    }

    /**
     * Return a String representation of this object.
     */
    public String toString() {

 if (filterConfig == null) return («FiltroLogin()»);
 StringBuffer sb = new StringBuffer(«FiltroLogin(«);
 sb.append(filterConfig);
 sb.append(«)»);
 return (sb.toString());

    }

    private void sendProcessingError(Throwable t, ServletResponse response) {
 
 String stackTrace = getStackTrace(t);

 if(stackTrace != null && !stackTrace.equals(«»)) {

     try {
     
  response.setContentType(«text/html»);
  PrintStream ps = new PrintStream(response.getOutputStream());
  PrintWriter pw = new PrintWriter(ps);
  pw.print(«<html>\n<head>\n<title>Error</title>\n</head>\n<body>\n»); //NOI18N
     
  // PENDING! Localize this for next official release
  pw.print(«<h1>The resource did not process correctly</h1>\n<pre>\n»);
  pw.print(stackTrace);
  pw.print(«</pre></body>\n</html>»); //NOI18N
  pw.close();
  ps.close();
  response.getOutputStream().close();;
     }
  
     catch(Exception ex){ }
 }
 else {
     try {
  PrintStream ps = new PrintStream(response.getOutputStream());
  t.printStackTrace(ps);
  ps.close();
  response.getOutputStream().close();;
     }
     catch(Exception ex){ }
 }
    }

    public static String getStackTrace(Throwable t) {

 String stackTrace = null;
    
 try {
     StringWriter sw = new StringWriter();
     PrintWriter pw = new PrintWriter(sw);
     t.printStackTrace(pw);
     pw.close();
     sw.close();
     stackTrace = sw.getBuffer().toString();
 }
 catch(Exception ex) {}
 return stackTrace;
    }

    public void log(String msg) {
 filterConfig.getServletContext().log(msg);
    }

    private static final boolean debug = true;
}

Filtroestud »« pagina para usuario y contraseña