Explore the number of JSP built-in objects and reveal their mysteries

JSP built-in objects

JSP built-in objects are objects that are automatically created by the JSP container at runtime and provided to the JSP page. These objects allow JSP pages to access container information and services, such as request and response objects, session objects, application objects, exception objects, page context objects, and configuration objects.

The specific number of JSP built-in objects

The specific number of JSP built-in objects depends on the implementation of the JSP container. Common JSP containers, such as Tomcat, Jetty and GlassFish, all support the following built-in objects:

• request: Represents the object of the current request.
• response: An object representing the current response.
• session: An object representing the current session.
• application: An object representing the current application.
• exception: Object representing the current exception.
• pageContext: Represents the context object of the current page.
• config: Indicates the configuration object of the current JSP page.

Code examples for JSP built-in objects

The following code examples demonstrate how to use JSP built-in objects:

<%@ page import="java.io.*" %>
<%
    // Get the request object.
    HttpServletRequest request = (HttpServletRequest) pageContext.getRequest();

    // Get the response object.
    HttpServletResponse response = (HttpServletResponse) pageContext.getResponse();

    // Get the session object.
    HttpSession session = request.getSession();

    // Get the application object.
    ServletContext application = pageContext.getServletContext();

    // Get the exception object.
    Exception exception = (Exception) request.getAttribute("javax.servlet.error.exception");

    // Get the page context object.
    PageContext pageContext = this.pageContext;

    // Get the configuration object.
    ServletConfig config = pageContext.getServletConfig();
%>

Conclusion

JSP built-in objects are objects that are automatically created by the JSP container at runtime and provided to the JSP page. These objects allow JSP pages to access container information and services, such as request and response objects, session objects, application objects, exception objects, page context objects, and configuration objects.

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