Blog by Rakesh.A

When you are developing web applications, its obvious that you’ll write code to generate paths for resources like images, stylesheets, scripts, etc. You can do this by simply using relative paths. In your JSP application, you can do this using ‘getContextPath()’ method of ‘HttpServletRequest’ object. Lets see what this method gives you. It returns a String value, the returned string will always have a leading ‘/’ character and will never have a trailing ‘/’. This method returns an empty string when you deploy your application as ROOT context and returns the subdomain context when deployed as subdomain. For example, if you name your WAR file as ‘myExample.war’ and deploy it in TOMCAT [by placing the WAR file in ‘webapps’ directory]. The ‘getContextPath()’ method will return ‘/myExample’. In your JSP page, if you’ve a image tag pointing to an image resource and you want it to work even when deployed as subdomain you can do that by using this ‘getContextPath()’ method as used below. ...

This example explains GET and POST methods of form submit using AJAX. Only code is posted for now, will try to update it later some time. Complete example can be downloaded using the link at the end of the post. package com.rakesh.ex.dto; public class EmployeeDTO {     private String empId;     private String name, email;     private String designation, department;     public EmployeeDTO(String empId) {         this.empId = empId;     }     public String getEmpId() {         return empId;     }     public void setEmpId(String empId) {         this.empId = empId;     }     public String getName() {         return name;     }     public void setName(String name) { ...

I’ve seen many developers who are at the early stages of their career have problems with this topic and seen many posts in forums asking how to do it – File Uploading using Servlets, JSP!; this article will provide an example using Commons File Upload API. I tried to make the example as simple as possible, hope it helps those early birds. Example uses JSP to provide the pages with form where user can select the file to upload with other form fields, Commons File Upload API to process submitted form and read form fields separately, and Servlets as middle layer between JSP and Commons File Upload API, example also has ANT build script to generate the distributables. All the code can be downloaded, links to these resources are provided at the end of this post, lets get on with the example then. The flow in this example is as depicted in the following picture. As you can see, user selects the file to upload and provides normal form data as well, using "index.jsp" and submi...

You will find many examples to learn how AJAX [Asynchronous Java Script And XML] works, but this one is different. Its one of the best way of using AJAX in web applications. The difference -  many of the examples you find uses Java Script to parse the AJAX response, this example avoids that parsing Java Script and uses JSP to generate the HTML and uses simple Java Script just to make the asynchronous call and show the response. It shows simple way of using JSP and AJAX with as much less Java Script as possible. This article wont go into details of what AJAX is and how to make AJAX calls, it explains one good way among many to use AJAX. Lets get on with it then! The flow of this example is like this – A simple JSP page where user performs an action [button click in this example] to get list of employees, on this action we’ll make an Asynchronous call to a Servlet which will prepare the dummy employee data and sends that data to a JSP page. This JSP generates the HTML displaying t...