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Getting started with SendRedirect in Servlet Collaboration

The sendRedirect() method of the HTTPServletResponse redirects responses from one page to another. This method allows you to move user content from one web page to the next.  In this article, we will see how the SendRedirect() gives the same functionalities.

Table of content

Table of content
Objectives
Prerequisites
SendRedirect method and its significance
Difference between SendRedirect method and RequestDispatcher forward method
Using SendRedirect method
Conclusion
References

An introduction to servlet collaboration using the RequesDispatcher() method can be found in this article.

In basic terms, the SendRedirect() method allows you to redirect a user's response to another web page, for example:

String country="Kenya";
if("Kenya".equals(n))
{
    response.sendRedirect("htmlPage.html");
}

SendRedirect() is used in the code snippet above to direct the client browser to the htmlPage if the condition is satisfied.

Objectives

At the end of this article, you should know the following:

The SendRedirect() method and its use.
Recognize the distinction between the SendRedirect() and forward() methods.
Using an example, learn how to implement the SendRedirect() method.

Prerequisites

Basic understanding of Java and the servlet's.
Basic understanding of the RequestDispatcher() method. You can learn more here.
Code editor installed on your machine, i.e. Eclipse, or Netbeans. In this article, we will use Eclipse IDE.
Tomcat Server installed on your computer. It's available for download on their official website. We'll use TomCat version 10 in this case.

SendRedirect method and its significance

One of the HttpServletResponse interface's methods is SendRedirect(). It's another way to use Servlet Collaboration to route client requests in the form of responses from one page to the next.

The main goal of this method is to send responses from a specific request to the desired web page.

Difference between SendRedirect method and RequestDispatcher forward method

The forward () method of the RequestDispatcher works on the server-side, while the SendRedirect() method works on the client-side.
Request dispatcher works on the request object, while SendRedirect() works on the response object.
The forward() method is also significantly faster than the SendRedirect(). This is because, unlike the forward() method, the SendRedirect() method necessitates two browser requests instead of one.
When the SendRedirect() method is used, the original URL is always changed. However, when the forward() method is applied, the original URL remains unchanged.

Using SendRedirect method

We'll make a program with the following pages to demonstrate how to use the SendRedirect method:

This page includes a login form and a paragraph indicating that the information entered is incorrect.

Servlet page

This page will assist us in determining whether the user's credentials are valid. The user's browser will get directed to the home page if the entered details are correct. If not, a login page will be displayed, and a message will pop up to show that the user has entered incorrect information.

Home page in HTML

If the user credentials are correct, the SendRedirect() method in the servlet page will redirect the user browser to this page.

Step 1: Creating the SendRedirectDemo project

Open Eclipse or any other Java IDE, create a new Dynamic web project by selecting a new Dynamic web project. Provide your favorite project name. In my case, I will call it SendRedirectDemo.

By right-clicking SendRedirectDemo and selecting New JSP, you can code a JSP page as shown. Provide your JSP class name. I will call mine login.

The JSP page's body is shown below:

<body>
<form action="SevletPage" method="post">
Enter User name <input type="text" name="userName" required><br>

Enter password <input type="password" name="password" required><br>
<input type="submit" value="login">
</form>
<%
String message=request.getParameter("message");

if("invalid".equals(message))
{
%>
<p>Wrong password or user name, please try again!</p>
<%} %>
</body>

Step 3: Creating a SevletPage

By right-clicking SendRedirectDemo and selecting New Servlet, you can code a Servlet page as shown below. Provide your Servlet class name. I will call it SevletPage.

package sendredirect.demo;

import java.io.IOException;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.*;

@WebServlet("/SevletPage")
public class SevletPage extends HttpServlet
{
	private static final long serialVersionUID = 1L;


	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException
	{
		String userName=request.getParameter("userName");
		String password=request.getParameter("password");
	if("Kenya".equals(userName)&& "12345".equals(password))
	{
		response.sendRedirect("home.html");
	}
	else
	{
		response.sendRedirect("Login.jsp?message=invalid");
	}
	}

}

HTML home page

To create this page, right-click on the project above and select new HTML. Finish by giving your HTML page a name. In this case, we will name it home.

The HTML page's body is shown below:

<body>
<h1>welcome to the home page</h1>
</body>

Click here to download the complete source code.

Conclusion

In conclusion, we learned about the SendRedirect() method and its use. We also understood the difference between the Java Servlet's SendRedirect() and forward() methods. You should now know how to implement the SendRedirect() method to create interactive web pages.

Happy coding!