Thursday, 17 April 2014

Servlets : RequestDispatcher Example


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RequestDispatcherDemo Project Dir Structure

LoginServlet.java
import java.io.IOException;
import java.io.PrintWriter;

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

public class LoginServlet 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("------------------------------------------------------");
 }

 public void doPost(HttpServletRequest request, HttpServletResponse response)
         throws ServletException, IOException
 {
  response.setContentType("text/html");
  PrintWriter out = response.getWriter();

  String userName = request.getParameter("username");
  String passWord = request.getParameter("password");

  if (userName.equalsIgnoreCase("ram") && passWord.equals("ram"))
  {
   RequestDispatcher requestDispatcher = request
           .getRequestDispatcher("/welcome");
   requestDispatcher.forward(request, response);
  }
  else
  {
   out.print("Sorry UserName or Password is Wrong!");
   RequestDispatcher requestDispatcher = request
           .getRequestDispatcher("/index.html");
   requestDispatcher.include(request, response);
  }
 }

 public void destroy()
 {
  System.out
          .println("------------------------------------------------------");
  System.out.println(" destroy method is called in "
          + this.getClass().getName());
  System.out
          .println("------------------------------------------------------");
 }
}
WelcomeServlet.java
import java.io.IOException;
import java.io.PrintWriter;

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

public class WelcomeServlet 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("------------------------------------------------------");
 }

 public void doPost(HttpServletRequest request, HttpServletResponse response)
         throws ServletException, IOException
 {

  response.setContentType("text/html");
  PrintWriter out = response.getWriter();

  String userName = request.getParameter("username");
  out.print("Welcome " + userName);
 }

 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>RequestDispatcherDemo</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>LoginServlet</servlet-name>
  <servlet-class>LoginServlet</servlet-class>
 </servlet>
 <servlet>
  <servlet-name>WelcomeServlet</servlet-name>
  <servlet-class>WelcomeServlet</servlet-class>
 </servlet>


 <servlet-mapping>
  <servlet-name>LoginServlet</servlet-name>
  <url-pattern>/login</url-pattern>
 </servlet-mapping>
 <servlet-mapping>
  <servlet-name>WelcomeServlet</servlet-name>
  <url-pattern>/welcome</url-pattern>
 </servlet-mapping>
 
</web-app>
index.html
<!DOCTYPE HTML>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>RequestDispatcherDemo</title>
</head>
<body>
 <form action="login" method="post">
  
  UserName :  <input type="text" name="username" /><br /> 
  
  Password :&nbsp; &nbsp; <input type="password" name="password" /><br /> 
   
  <input type="submit" value="login" />
  
 </form>
</body>
</html>
Environment Used

JDK version :1.6.0_30
Tomcat version : 7.0.50

To Download RequestDispatcherDemoApp Project Click the below link
https://sites.google.com/site/javaee4321/servlets/RequestDispatcherDemoApp.zip?attredirects=0&d=1

See also:

  • Servlets Tutorial
  • All Design Patterns Links
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