In JSP, the application is an implicit object of type ServletContext. It is created once by the web container when the web application is deployed and is shared across all JSP pages. It is mainly used to store and retrieve data that is accessible throughout the entire application.
- Available to all JSP pages (application scope)
- Helps access initialization parameters from web.xml
- Used to share data globally across users
Common Methods of Application Object
- setAttribute(String, Object): Stores data in application scope
- getAttribute(String): Retrieves stored data
- removeAttribute(String): Removes stored attribute
- getAttributeNames(): Returns all attribute names
- getInitParameter(String): Retrieves initialization parameter from
web.xml - getInitParameterNames(): Returns all initialization parameters
- getRealPath(String): Converts virtual path to actual system path
- log(String): Writes message to server log
- getServerInfo(): Returns server information
Step-by-Step Implementation of JSP Application
This section explains the process of creating and configuring JSP files to use the application implicit object for sharing data across the entire application.
Step 1: Create index.html
- Create an HTML form to take user input
- On submit, data is sent to welcome.jsp
index.html file
Step 2: Configure web.xml
- Define servlet mapping
- Add context parameter
web.xml file
Step 3: Create welcome.jsp
- Retrieve user input using request.getParameter()
- Access application data using application.getInitParameter()
- Display both values
welcome.jsp
