A summary of the nine built-in objects of JSP and their functions

Overview of the nine built-in objects in JSP and their functions

JSP (JavaServer Pages) is a dynamic web page technology that allows developers to embed Java code. JSP built-in objects provide access to the server environment, request and response objects, and other resources. These objects are very useful for JSP developers to simplify the development process and improve development efficiency.

The nine built-in objects in JSP and their functions are summarized as follows:

1. request: represents the current HTTP request. It provides access to request parameters, request headers, request body, and other request information.
2. response: Indicates the current HTTP response. It provides access to response headers, response body, and other response information.
3. session: Indicates the current user session. It provides access to session properties and other session information.
4. application: Indicates the current Web application. It provides access to application properties and other application information.
5. out: Indicates the current output stream. It provides access to the output content of the JSP page.
6. page: Indicates the current JSP page. It provides access to JSP page properties and other page information.
7. pageContext: Indicates the current JSP page context. It provides access to request, response, session, application, out and page objects.
8. config: Indicates the current JSP page configuration object. It provides access to JSP page configuration parameters and other configuration information.
9. exception: Indicates the current exception object. It provides access to exception information.

The following is a detailed introduction to the specific functions of each built-in object:

1. request: The request object provides access to request parameters, request headers, request bodies, and other request information. . For example, you can use request.getParameter("name") to get the value of the request parameter "name".
2. response: The response object provides access to response headers, response body, and other response information. For example, you can use response.setContentType("text/html") to set the content type of the response.
3. session: The session object provides access to session properties and other session information. For example, you can use session.setAttribute("name", "value") to set the value of the session attribute "name".
4. application: The application object provides access to application properties and other application information. For example, you can use application.setAttribute("name", "value") to set the value of the application attribute "name".
5. out: The out object provides access to the output content of the JSP page. For example, you can use out.println("Hello World!") to output "Hello World!" in a JSP page.
6. page: The page object provides access to JSP page properties and other page information. For example, you can use page.getAttribute("name") to get the value of the JSP page attribute "name".
7. pageContext: The pageContext object provides access to the request, response, session, application, out, and page objects. For example, you can use pageContext.getRequest() to obtain the request object.
8. config: The config object provides access to JSP page configuration parameters and other configuration information. For example, you can use config.getInitParameter("name") to get the value of the JSP page configuration parameter "name".
9. exception: The exception object provides access to exception information. For example, you can use exception.getMessage() to get the details of the exception message.

JSP built-in objects are very useful for JSP developers to simplify the development process and improve development efficiency. By understanding and using these built-in objects, JSP developers can create more powerful and dynamic Web pages.

The above is the detailed content of A summary of the nine built-in objects of JSP and their functions. For more information, please follow other related articles on the PHP Chinese website!