Your own Cookie!

By -
In this post we will see how to create a simple web app which uses cookies to hold the user data (remember, in http ever request is a new request and cookie is a way to store the user data for subsequent requests to the server).

Refer Cookies in Servlet for information about cookies

Setup tomcat on your machine. (I have used apache-tomcat-8.0.15)
I am using eclipse for installation. Create a dynamic web project, Cookies

My final project structure looks like this:



How to deploy our war file in tomcat.
Export project -> as WAR file -> save it as Cookies in the webapps folder of tomcat.
Start tomcat using startup.bat in bin folder.
Access http://localhost:8080/Cookies/

Create an index.html file:

<form action="servlet1" method="post">
Name : <input type="text" name="name">
<input type="submit" value="Go">
</form>


Create FirstServlet.java class.

package com.cookie.servlets;

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

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

public class FirstServlet extends HttpServlet {

@Override
public void doPost(HttpServletRequest request, HttpServletResponse response) {
try {
String name = request.getParameter("name");

response.setContentType("text/html");

PrintWriter out = response.getWriter();
Cookie c = new Cookie("name", name);
response.addCookie(c);
out.write("Hello " + name);
out.print("<form action='servlet2' method='post'>");  
   out.print("<input type='submit' value='go'>");  
   out.print("</form>");
   out.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}

}

}


Your web.xml file:

<web-app>

 <servlet>
<servlet-name>servlet1</servlet-name>
<servlet-class>com.cookie.servlets.FirstServlet</servlet-class>
</servlet>

 <servlet-mapping>
<servlet-name>servlet1</servlet-name>
<url-pattern>/servlet1</url-pattern>
</servlet-mapping>

 </web-app>


<-- You can deploy and check at this point -->

Next we create our next servlet, SecondServlet.java


package com.cookie.servlets;

 import java.io.PrintWriter;

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

 public class SecondServlet extends HttpServlet{

 @Override
public void doPost(HttpServletRequest request, HttpServletResponse response){
try{
response.setContentType("text/html"); 
PrintWriter out = response.getWriter();  
     
   Cookie ck[]=request.getCookies();  
   out.print("Hello "+ck[0].getValue());  
 
   out.close();  
}catch(Exception e){
e.printStackTrace();
}
}


}

Add the following to web.xml

<servlet>
<servlet-name>servlet2</servlet-name>
<servlet-class>com.cookie.servlets.SecondServlet</servlet-class>
</servlet>

<servlet-mapping>
<servlet-name>servlet2</servlet-name>
<url-pattern>/servlet2</url-pattern>
</servlet-mapping>

Your final web.xml looks like this:

<web-app>

<servlet>
<servlet-name>servlet1</servlet-name>
<servlet-class>com.cookie.servlets.FirstServlet</servlet-class>
</servlet>

<servlet-mapping>
<servlet-name>servlet1</servlet-name>
<url-pattern>/servlet1</url-pattern>
</servlet-mapping>


<servlet>
<servlet-name>servlet2</servlet-name>
<servlet-class>com.cookie.servlets.SecondServlet</servlet-class>
</servlet>

<servlet-mapping>
<servlet-name>servlet2</servlet-name>
<url-pattern>/servlet2</url-pattern>
</servlet-mapping>

</web-app>


Deploy and run.





Use cookie.setMaxAge(0) to delete the cookie information.

Refer Cookies in Servlet for information about cookies


Comments

Post a Comment

Popular posts from this blog

Writing your own ejabberd Module

By -
Coming soon: What is ejabberd? What is erlang? Installation details. I will start with writing the ejabberd module first. Once you have done all the installations: sudo make sudo make install sudo ejabberdctl start sudo ejabberdctl stop You can check the status using: sudo ejabberdctl status You can locate logs at: (With default installation) /var/log/ejabberd All config related changes will be mainly done at: /etc/ejabberd/ejabberd.yml You will need a basic understanding of erlang. You can take a short crash course at: http://www.erlang.org/course/course.html This is a good reference. Go to your ejabberd-15.07/src directory. This is where you will write the hook for your ejabberd server. Create a file, say mod_changeBody.erl. Your module name and file name should be same. Add the following basic contents into your erl file: -module(mod_changeBody). -behavior(gen_mod). -include("ejabberd.hrl"). -include("logger.hrl"). -expo
Read more

npm ECONNREFUSED error

By -
If you face error which says ECONNREFUSED while doing npm install <<package name>>, you are probably behind a proxy which is not allowing you to connect to the server and download the packages required. Just follow the below steps: npm config set proxy  http://your_proxy_name:port npm config set https-proxy https://your_proxy_name:port And then try npm install How to get npm config? npm get proxy will do the work :)
Read more

Conditional Flow - Spring Batch Part 6

By -
Jump to Conditional Flow using Custom Status There can be muliple scenario where you want your jobs to proceed depending on the outcome of your steps. For example, in case of our Corporate gifts shop, in case the automatic packaging of the gifts fails, we want some manual intervention to be done i.e. somebody should manually package the item.  IF-ELSE IF loop for packaging:     if packageStep fails                              then manualPackageStep                         else if packageStep executes successfully                              then sendOutForDelivery Entire code available at git repo:   https://github.com/ricsr/spring-batch-demo/tree/exercise_06 Using SpringBatch you can achieve it as follows: Create you manualPackageStep, which is very similar to your packageStep, except that it does the packaging manually. @Bean public Step manualPackageStep () { return this . stepBuilderFactory .get( "manualPackageStep" ).tasklet( new Tasklet() { @Override pu
Read more