JSP built-in objects and El expression built-in object myths

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JSP nine large built-in objects

11 objects implied by an EL expression

Implied object name	Description
PageContext	Corresponds to the PageContext object in the JSP page (note: The PageContext object is taken.) ）
Pagescope	Represents the Map object in the page field for saving properties
Requestscope	Represents the Map object in the Request field for saving properties
Sessionscope	Represents the Map object in the Session field for saving properties
Applicationscope	Represents the Map object in the Application field for saving properties

Implied object name	Description
Param	Represents a map object that holds all the request parameters
Paramvalues	Represents a map object that holds all the request parameters, and it returns a string[for a request parameter]
Header	Represents a map object that holds all the HTTP request header fields
Headervalues	Ibid., return string[] array. Note: If there is "-" in the head, example accept-encoding, headervalues["accept-encoding"]
Cookies	Represents a map object that holds all cookies
Initparam	Represents a map object that holds all the Web application initialization parameters

Attention:

①: If the value is placed in the domain object can be obtained by ${requestscope.key}, or you can omit requestscope that is ${key}

②: But to get request,session and other objects must use PageContext to obtain, that is ${pagecontext.request.contextpath} and so on

JSP built-in objects and El expression built-in object myths