[Jsp] Implicit Object_2

Implicit Object_2

1. application implicit

- application is an implicit object of type ServletContext

- The instance of ServletContext is created only one by the web container when application or project is deployed on the server

- This object can be used to get initialization parameter from configuration file(web.xml)

1_1 index.html

1_2. web.xml

1_3. welcome.jsp

2. session implicit

- The Java developer can use this object to set, get or remove attriute or to get session info

2_1. index.html

2_2. welcome.jsp

2_3. second.jsp

3. pageContext implicit

- The pageContext object can be used to set, get or remove attribute from one of the following scopes

• page
• request
• session
• application      

3_1. index.html

3_2. welcome.jsp

3_3. second.jsp

4. page implicit

- This object is assigned to the reference of auto generated servlet class

Object page = this;

4_1. Example

<% (HttpServlet)page.log("message"); %>

- You can use this object directly in jsp

<% this.log("message"); %>

5. exception implicit

- This object can be used to print the exception. But it can only be used in error pages. 

5_1. error.jsp