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

Source: Internet
Author: User

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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

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