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| Tips & Tricks |
| |
String password = ((HttpServletRequest)
req).getParameter(“password”);
// Check whether it matches with the desired
password.
if(password.equals(“mypassword”)) {
long start = System.currentTimeMillis();
String address = req.getRemoteAddr();
String file = ((HttpServletRequest)
req).getRequestURI();
// Pass control to the WelcomeServlet’s
service() method
chain.doFilter(req, res);
// After returning the control back to the
filter, log user ip, resource uri and time used .
filterConfig.getServletContext().log(“ User IP:
“ + address + “ Resource: “ + file + “
Milliseconds used: “ +
(System.currentTimeMillis() - start) );
}
else {
// If password doesn’t match then send
the page informing incorrect password.
res.setContentType(“text/html”);
PrintWriter pw = res.getWriter();
pw.println(“<html>”);
pw.println(“<head><title>Wrong
Password</title></head>”);
pw.println(“<body>”);
pw.println(“<h3>Sorry, the password
was incorrect.</h3>”);
pw.println(“</body>”);
pw.println(“</html>”);
}
}
public void destroy() { }
} |
WelcomeServlet.java
import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
import java.util.*;
public class WelcomeServlet extends
HttpServlet {
public void doGet(HttpServletRequest req,
HttpServletResponse res) throws |
|
|
ServletException, IOException {
res.setContentType(“text/html”);
PrintWriter out = res.getWriter();
String username =
req.getParameter(“username”);
out.println(“<html><body>Welcome :
<b>”+username+”<br/><br/>”);
out.println(new Date().toString());
out.println(“</b></body></html>”);
}
} |
To make the filter work, declare the filter in
Deployment Descriptor. If filter is required to
be used only when the specific servlet is
requested then filter is mapped to that
servlet. To create a filter mapping for a
specific servlet, map the filter to the name of
a servlet by specifying the name of the filter
in <filter-name> element and servlet’s name
in <servlet-name> element.
Web.xml
<?xml version=”1.0" encoding=”ISO-8859-
1"?>
<!DOCTYPE web-app
PUBLIC “-//Sun Microsystems, Inc.//DTD Web
Application 2.2//EN”
“http://java.sun.com/j2ee/dtds/webapp_
2_2.dtd”>
<web-app>
<filter>
<filter-name>MyFilter</filter-name>
<filter-class>MyFilter</filter-class>
</filter>
<filter-mapping>
<filter-name>MyFilter</filter-name>
<servlet-name>WelcomeServlet</servletname>
</filter-mapping>
<servlet>
<servlet-name>WelcomeServlet</servletname>
<servlet-class>WelcomeServlet</servletclass>
</servlet>
<servlet-mapping>
<servlet-name>WelcomeServlet</servlet- |
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Dec 2007 | Java Jazz Up | 77 |
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