Nine built-in objects in JSP

JSP contains nine objects of that type. These nine built-in objects are examples of servletapi classes or interfaces,

Only JSP specifications initialize them by default, that is, they are already objects and can be used directly.

 

1. Application: an instance of javax. servlet. servletcontext.

 

2. config: the instance of javax. servlet. servletconfig. This instance represents the configuration information of JSP.

 

3. Exception: Java. Lang. throwable instance, which indicates exceptions and errors on other pages. This object can be used only when the iserrorpage of the compilation command page is true.

 

4. Out: javax. servlet. jsp. jspwriter instance. This instance represents the output stream of JSP and is used to generate HTML for the output content.

 

5. Page: indicates the page itself, which is usually of little use, that is, this in servlet. Its type is the generated servlet.

 

6. pagecontext: the instance of javax. servlet. jsp. pagecontext. This object indicates the JSP page context. You can use this method to access the shared data on the page.

 

7. Request: For an instance of javax. servlet. http. httpservletrequest, client request parameters are encapsulated in this object.

 

8. Response: javax. servlet. http. httpservletresponse instance. The response from the server to the client. This object is rarely used for direct response,

The output response uses the out object, while the response is often used for redirection. Common methods include:

 

9. sendredirect (Java. Lang. String localtion)

 

10. Session: the instance of javax. servlet. http. httpsession. This object represents a session