What are jsp built-in objects

jsp built-in objects refer to some predefined objects in jsp. Can be used directly in the page, these built-in objects provide many useful functions and properties, making it easier for developers to process and manipulate data. Common built-in objects in JSP include request object, response object, out object, session object, application object, config object, pageContext object, exception object, etc.

# Operating system for this tutorial: Windows 10 system, Dell G3 computer.

JSP (Java Server Pages) is a Java technology used to develop dynamic web applications. In JSP, there are some built-in objects that can be used directly in the page. These built-in objects provide many useful functions and properties, making it easier for developers to process and manipulate data.

The following are common built-in objects in JSP:

request object: The request object encapsulates the information of the HTTP request issued by the client, including request parameters, request headers, Request method etc. Through the request object, developers can obtain user-submitted data, such as form data, URL parameters, etc.

response object: The response object is used to send an HTTP response to the client. Through the response object, developers can set response headers, response status codes, send response content, etc.

out object: The out object is a PrintWriter type object used to send text to the client. Through the out object, developers can output text, HTML tags, JavaScript code, etc. in JSP pages.

session object: The session object is used to share data between multiple requests. It is a server-side object that stores the user's session information. Through the session object, developers can store and obtain the user's login status, shopping cart contents, etc.

application object: The application object is a global object used to share data throughout the application. It is created when the application starts and destroyed when the application is closed. Through the application object, developers can store and obtain global configuration information, shared resources, etc.

config object: The config object provides a method to access the JSP page configuration information. Through the config object, developers can obtain the initialization parameters, servlet context, etc. of the JSP page.

pageContext object: The pageContext object is the context object of a JSP page, which contains references to other built-in objects. Through the pageContext object, developers can access the methods and properties of any built-in object.

exception object: The exception object is used to handle exceptions in JSP pages. It is a predefined variable in a JSP page. When an exception occurs on the JSP page, the exception object will be automatically instantiated, and developers can obtain exception information through it.

These built-in objects are very useful in JSP development. They provide many convenient methods and properties, allowing developers to process and manipulate data more conveniently. By using these built-in objects flexibly, powerful and dynamic web applications can be developed efficiently.

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