Friday 2 May 2014

Servlets : PageAutoRefresh


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PageAutoRefresh Project Dir Structure

PageRefreshServlet.java
import java.io.IOException;
import java.io.PrintWriter;
import java.util.Calendar;
import java.util.GregorianCalendar;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class PageRefreshServlet extends HttpServlet
{

    private static final long serialVersionUID = 1L;

    public void init() throws ServletException
    {
        System.out
                .println("------------------------------------------------------");
        System.out.println(" Init method is called in "
                + this.getClass().getName());
        System.out
                .println("------------------------------------------------------");
    }

    // Method to handle GET method request.
    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException
    {
        
        System.out.println(" doGet method is called in "
                + this.getClass().getName());
        
        // Set refresh, autoload time as 5 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();
        String title = "Auto Page Refresh using Servlet";
        String docType = "<!doctype html public \"-//w3c//dtd html 4.0 "
                + "transitional//en\">\n";
        out.println(docType + "<html>\n" + "<head><title>" + title
                + "</title></head>\n" + "<body bgcolor=\"#f0f0f0\">\n"
                + "<h1 align=\"center\">" + title + "</h1>\n"
                + "<p>Current Time is: " + CT + "</p>\n");
    }

    // Method to handle POST method request.
    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException
    {
        doGet(request, response);
    }

    public void destroy()
    {
        System.out
                .println("------------------------------------------------------");
        System.out.println(" destroy method is called in "
                + this.getClass().getName());
        System.out
                .println("------------------------------------------------------");
    }
}

web.xml
<?xml version="1.0" encoding="ISO-8859-1"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns="http://java.sun.com/xml/ns/javaee"
    xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"
    metadata-complete="true" version="3.0">

      <display-name>PageAutoRefresh</display-name>

      <description>
        This is a simple web application with a source code organization
        based on the recommendations of the Application Developer's Guide.
      </description>

       <servlet>
        <servlet-name>refresh</servlet-name>
        <servlet-class>PageRefreshServlet</servlet-class>
    </servlet>
    
    <servlet-mapping>
        <servlet-name>refresh</servlet-name>
        <url-pattern>/PageRefresh</url-pattern>
    </servlet-mapping>
</web-app>

index.html
<!DOCTYPE HTML>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>PageRefresh</title>
</head>
<body>
    <li><a href="PageRefresh">PageRefresh</a></li>
</body>
</html>


Environment Used 

JDK version :1.6.0_30
Tomcat version : 7.0.50 

To Download PageAutoRefreshApp Project Click the below link

https://sites.google.com/site/javaee4321/servlets/PageAutoRefreshApp.zip?attredirects=0&d=1

 See also:

  • Servlets Tutorial
  • All Design Patterns Links
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