Javaweb--jsp nine large built-in Objects complete summary

　　Features of built-in objects:

1. Provided by the JSP specification, without being instantiated by the creator.

2. Implementing and managing through the Web container

3. All JSP pages can be used

4. Available only in expressions or snippets of script elements (<%= using built-in object%> or <% using built-in objects%>)

　　Nine large built-in objects and common methods:

1.request Object (Request information Javax.servlet.http.HttpServletrequest)

Method name	Description
IsUserInRole	Determine if the authenticated user belongs to a member group
GetAttribute	Gets the value of the specified property, as if the property value does not exist return null
Getattributenames	Gets the collection of all property names
GetCookies	Get all Cookie objects
Getcharacterencoding	Gets the character encoding of the request
Getcontentlength	Returns the length of the request body, as indeterminate returns-1
GetHeader	Gets the specified name header value
Getheaders	Gets all values of the specified first name header, an enumeration
Getheadernames	Gets the name of all the headers, an enumeration
getInputStream	Returns the request input stream to get the data in the request
GetMethod	Get a way for clients to transfer data to the server side
GetParameter	Gets the specified name parameter value
Getparameternames	Gets the name of all parameters, an enumeration
Getparametervalues	Gets all values for the specified name parameter
Getprotocol	Gets the protocol name that the client sends data to the server side
GetQueryString	Gets the query string that is passed to the server in the Get method
Getrequesturi	Gets the client address that issued the request string
Getremoteaddr	Get the IP address of the client
Getremotehost	Get the name of the client
GetSession	Get and request a related session
getServerName	Get the name of the server
Getserverpath	Get the path to the client request file
Getserverport	Get the port number of the server
RemoveAttribute	Delete a property in the request
SetAttribute	Set the specified name parameter value

2.response Object (Response Javax.servlet.http.HttpServletResponse)

Method name	Description
Addcookie	Add a Cookie Object
AddHeader	Add an HTTP file to specify header information
Containsheader	Determines whether the specified name HTTP file header information exists
Encodeurl	Using SessionID to encapsulate URLs
Flushbuffer	Forces the current buffer content to be sent to the client
GetBufferSize	return buffer size
Getoutputstream	Returns the output stream object to the client
Senderror	Send error message to client
Sendredirect	Send the response to another location for processing
setContentType	Set the MIME type of the response
SetHeader	Sets the HTTP header information for the specified name

　　

3.session Object (Session javax.servlet.http.HttpSession)

Method name	Description
GetAttribute	Gets the property of the specified name
Getattributenames	Gets the name of all the attributes in the session, an enumeration
GetCreationTime	Returns the creation time of the session
GetId	Get the session identifier
Getlastaccessedtime	Returns the last time the request was sent
Getmaxinactiveinterval	Returns the time-to-live unit of Session object 1 per thousand seconds
Invalidate	Destroying session objects
IsNew	Whether each request will produce a new session object
RemoveAttribute	Delete the property of the specified name
SetAttribute	Sets the property value of the specified name

4.application Objects (Application Javax.servlet.ServletContext)

Method name	Description
GetAttribute	Gets the property value of the specified name in the Application object
Getattributenames	Gets the name of all the properties in the Application object, an enumeration
Getinitparameter	Returns the initial parameter value of the specified name in the applied object
Getservletinfo	Returns the current version information in the servlet compiler
SetAttribute	Sets the attribute value for the specified name in the Application object

5.out objects (data flow javax.servlet.jsp.jspWriter)

Method name	Description
Print or println	Output data
NewLine	Output line break characters
Flush	Output buffer Data
Close	Turn off the output stream
Clear	Clears the data in the buffer but does not output to the client
Clearbuffer	Clears data from buffer, outputs to client
GetBufferSize	Get buffer size
Getremaining	Get space that is not occupied in the buffer
Isautoflush	is auto-output

6.pageContext Object (page context Javax.servlet.jsp.PageContext)

Method name	Description
Forward	Redirect to another page or servlet component
GetAttribute	Gets the property value of the specified name in a range
Findattribute	Search for properties of specified names by range
RemoveAttribute	Delete a property of a specified name in a range
SetAttribute	Sets the attribute value of a specified name in a range
GetException	Returns the current exception object
Getrequest	Returns the current Request object
GetResponse	Returns the current Response object
Getservletconfig	Returns the ServletConfig object of the current page
Getservletcontext	Returns all page-Shared ServletContext objects
GetSession	Returns the session object for the current page

7.config Object (servlet configuration information Javax.servlet.ServletConfig)

Method name	Description
Getservletcontext	Returns the Environment object of the servlet being executed
Getservletname	Returns the name of the servlet being executed
Getinitparameter	Returns the initial parameter value for the specified name
Getinitparameternames	Returns all the initial parameter names in the JSP, an enumeration

8.page object (An instance of the current JSP, java.lang.object)

It means that the JSP is compiled into a servlet, which can be used to invoke methods defined in the Servlet class

9.exception object (Run-time exception, java.lang.Throwable)

The result of the called error page can only be used in the error page.

That is set in the page directive: <% @page iserrorpage= "true"%>

Javaweb--jsp nine large built-in Objects complete summary