The public service(HttpServletRequest req, HttpServletResponse res) method in the servlet component should extend HttpServlet (AC). It allows the browser to refresh the web page when a certain amount of time has passed. Auto-refresh can be enabled in two ways:
- setHeader(“refresh”, String “<time-in-second>”)
- setIntHeader(“refresh”, int <time-in-second>)
“refresh” is fixed in these approaches. Time is passed to the setHeader() method as a string, while time is passed to the setIntHeader() method as an int number. The time should be expressed as a fraction of a second.
Example:
setIntHeader("Refresh", 5);
Auto Page Refresh Example
This is the PageRefresh.java file where we have written page refresh logic code
Java
import java.io.*;import javax.servlet.*;import javax.servlet.http.*;import java.util.*; public class PageRefresh extends HttpServlet{ public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { // Set refresh time as 1 seconds response.setIntHeader("Refresh", 5); // Set response content type response.setContentType("text/html"); // Get current time Calendar calendar = new GregorianCalendar(); String am_pm; int hour = calendar.get(Calendar.HOUR); int minute = calendar.get(Calendar.MINUTE); int second = calendar.get(Calendar.SECOND); if(calendar.get(Calendar.AM_PM) == 0) { am_pm = "AM"; } else { am_pm = "PM"; } String CT = hour+":"+ minute +":"+ second +" "+ am_pm; PrintWriter out = response.getWriter(); out.println("<h1 align='center'>Auto Refresh Page</h1>"); out.println("<h2 align='center'>Current time: "+CT+"</h2>"); } // Handle POST method request. public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doGet(request, response); }} |
Following is the web.xml file:
XML
<web-app> <servlet> <servlet-name>PageRefresh</servlet-name> <servlet-class>PageRefresh</servlet-class> </servlet> <servlet-mapping> <servlet-name>PageRefresh</servlet-name> <url-pattern>/PageRefresh</url-pattern> </servlet-mapping></web-app> |
Output:
It refreshes the browser every five seconds and the current time will be changed automatically.
