How do I automatically refresh a servlet?
Author: Deron Eriksson
Description: This tutorial describes how to add a Refresh response header to refresh a servlet.
Tutorial created using:
Windows XP || JDK 1.5.0_09 || Eclipse Web Tools Platform 2.0 (Eclipse 3.3.0) || Tomcat 5.5.20
There are a couple primary ways in which a servletW can be automatically refreshed. This tutorial shows both methods. One way is to add a "Refresh" response header containing the number of seconds after which a refresh should occur. The TestServlet class below shows an example of this. TestServlet.javapackage com.cakes; import java.io.IOException; import java.io.PrintWriter; import java.util.Date; import javax.servlet.ServletException; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; public class TestServlet extends javax.servlet.http.HttpServlet implements javax.servlet.Servlet { private static final long serialVersionUID = 1L; protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { performTask(request, response); } protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { performTask(request, response); } private void performTask(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { response.setContentType("text/html"); response.addHeader("Refresh", "5"); PrintWriter out = response.getWriter(); out.println("TestServlet says hi at " + new Date()); } } The response.addHeader("Refresh", "5") call adds a response header that is sent back to the client indicating that the browser should make another request of the servlet after 5 seconds. ![]() We can see that the browser refreshes every five seconds, as shown below. ![]() A second way to perform a refresh is to include a meta refresh in the HTMLW sent to the client browser. The following meta refresh performs a refresh after 5 seconds. <meta http-equiv="refresh" content="5" /> In the following example, the client browser is redirected to www.google.com after 5 seconds. <meta http-equiv="refresh" content="5;url=http://www.google.com" /> Related Tutorials: |