Block Filter : Filter « Servlets « Java
Block Filter
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
public class BlockFilter implements Filter {
private FilterConfig config;
/** Creates new BlockFilter */
public BlockFilter() {
}
public void init(FilterConfig filterConfig) throws ServletException {
this.config = filterConfig;
}
public void doFilter(ServletRequest request, ServletResponse response,
FilterChain chain) throws IOException, ServletException {
HttpServletRequest req = null;
boolean authenticated = false;
PrintWriter out = null;
if (request instanceof HttpServletRequest) {
req = (HttpServletRequest) request;
String user = req.getParameter("user");
authenticated = authenticateUser(user);
}
if (authenticated) {
chain.doFilter(request, response);
} else {
response.setContentType("text/html");
out = response.getWriter();
out
.println("<html><head><title>Authentication Response</title></head><body>");
out.println("<h2>Sorry your authentication attempt failed</h2>");
out.println("</body></html>");
out.close();
}
}// doFilter
public void destroy() {
/*
* called before the Filter instance is removed from service by the web
* container
*/
}
private boolean authenticateUser(String userName) {
//authenticate the user using JNDI and a database, for instance
return false;
}
}
