How to use JSP suppressed objects __jsp

One, Page object

The Page object represents the JSP itself, or rather, it represents the JSP-translated servlet, which can invoke the method defined by the Servlet class.

Two, config object
The Config object holds some of the servlet's initial data structures.
The Config object is implemented in the Javax.servlet.ServletConfig interface, which has the following four methods:

Public String Getinitparameter (name)	Returns the initialization parameter of type string
Public Java.util.Enumeration Getinitparameternames ()	Returns the names of all initialization parameters
Public ServletContext Getservletcontext ()	Get the server applet environment for the current server applet or JSP page
Public sring Getservletname ()	Get the name of the current server applet or JSP page

third, Request object
The Request object contains all the requested information, such as the source of the request, the header, the cookies and the parameter values associated with the request, and so on.
The request object implements the Javax.servlet.http.HttpServletRequest interface, and the method provided can divide it into four main categories:
1. Methods of storing and acquiring property;

void SetAttribute (String name, Object value)	Set the value of the Name property to
Enumeration Getattributenamesinscope (int scope)	Get Properties for all scope scopes
Object getattribute (String name)	Gets the value of the Name property
void RemoveAttribute (String name)	Remove the value of the Name property

2. Method of Obtaining request parameter

Stringgetheader (Stringname)	Get the header of name
Enumerationgetheadernames ()	Get all the header names
Enumerationgetheaders (Stringname)	Gets the headers for all the name
Intgetintheader (Stringname)	Gets the header of the integer type name
Longgetdateheader (Stringname)	Gets the header of the date type name
Cookie[]getcookies ()	Obtain cookies related to the request

3. The ability to obtain the request HTTP header method

Stringgetcontextpath ()	Get the context path (that is, the platform name)
Stringgetmethod ()	Method of getting HTTP (get, POST)
Stringgetprotocol ()	Access to the protocol used (http/1.1, http/1.0)
Stringgetquerystring ()	Gets the requested parameter string, however, the HTTP method must be a get
Stringgetrequestedsessionid ()	Get the SessionID on the client side
Stringgetrequesturi ()	Gets the URL of the request, but does not include the requested parameter string
STRINGGETREMOTEADDR ()	Get the user's IP address
Stringgetremotehost ()	Get the user's host name
Intgetremoteport ()	Get the user's host port
Stringgetremoteuser ()	Get the name of the user
Voidetcharacterencoding (stringencoding)	Set the encoding format to solve the problem of the form passing Chinese

      Four, response  objects
    response  The object mainly passes the results of jsp  processing data back to the client. The
    response  object is the implementation of the javax.servlet.http.httpservletresponse  interface. Response the method provided by the object.
    1. To set the table header method

Voidaddcookie (Cookiecookie)	Add cookies
Voidadddateheader (Stringname,longdate)	New Long value to name header
Voidaddheader (Stringname,stringvalue)	New String type value to name header
Voidaddintheader (Stringname,intvalue)	New value of int type to name header
Voidsetdateheader (Stringname,longdate)	Specifies a long value to the name header
Voidsetheader (Stringname,stringvalue)	Specify string value to name header
Voidsetintheader (Stringname,intvalue)	Specifies the value of type int to the name header

2. The method of setting the response status code

Voidsenderror (INTSC)	Transfer Status code (STATUSCODE)
Voidsenderror (INTSC,STRINGMSG)	Transfer status codes and error messages
Voidsetstatus (INTSC)	Set the status code

3. Method for URL rewriting (rewriting)

Stringencoderedirecturl (StringUrl)

Encode URLs that use the Sendredirect () method

Five, out objects
An Out object can output the results to a Web page.
Out is mainly used to control the output stream of buffers (buffer) and output streams.

Voidclear ()	Clears the contents of the output buffer
Voidclearbuffer ()	Clears the contents of the output buffer
Voidclose ()	Turn off the output stream and clear all content
Intgetbuffersize ()	Gets the current buffer size in kilobytes (KB)
Intgetremaining ()	Gets the remaining buffer size (KB) after the current use
Booleanisautoflush ()	The return true indicates that the buffer is automatically cleared when it is full; False indicates that no automatic cleanup and exception handling is generated

 
Six, Session Object
The Session object represents the current sessions status of individual users.
The session object implements the Javax.servlet.http.HttpSession interface, the method provided by the HttpSession interface

Longgetcreationtime ()	Get the time that the session was generated, in milliseconds
Stringgetid ()	Get the ID of the session
Longgetlastaccessedtime ()	Get the time the user finally sent the request through this session
Longgetmaxinactiveinterval ()	To get the maximum session inactivity time, and if this time is exceeded, sessions will expire
Voidinvalidate ()	Cancel the Session object and discard the contents of the object completely
Booleanisnew ()	To determine whether the session is "new"
Voidsetmaxinactiveinterval (intinterval)	To set the maximum session inactivity time, if more than this time, sessions will be invalidated td>

      VII, application objects
     Application objects are most commonly used in accessing information in the environment.
     Because information about the environment is usually stored in ServletContext, application objects are often used to access information in ServletContext.
    application  Object implements the javax.servlet.servletcontext  interface, ServletContext the method provided by the interface container

for the specified localurl

intgetmajorversion ()	container main servletapi version
intgetminorversion ()	Get container minor Servletapi version
Stringgetserverinfo ()	Gets the name and version of the container
Stringgetmimetype (stringfile)	Get the MIME type of the specified file
Servletcontextgetcontext (stringuripath)	Get applicationcontext
Stringgetrealpath (stringpath)	Get absolute path to local path
Voidlog (stringmessage)	Writes information to the log file
Voidlog (stringmessage,throwablethrowable)	Writes exception information generated by StackTrace to the log file

     Eight, PageContext object
    pagecontext objects can access other suppressed objects. The
    1.pagecontext object accesses other suppressed object properties, at which point you need to specify a parameter for the range.
        object getattribute (string name, int  Scope)
        enumeration getattributenamesinscope (int  Scope)
        void removeattribute (string name, int  scope)
        void setattribute (String name,  Object value, int scope)
     range parameters are four, representing four ranges: Page_scope, Request_scope, Session_scope, Application_scope
    2.pagecontext objects Get methods for other suppressed objects

exceptiongetexception ()	Return the exception for the current page, but this page is errorpage,
Jspwritergetout ()	Return the current page's output stream, for example: Out
Objectgetpage ()	To return the servlet entity (instance) of the current Web page, for example: page
Servletrequestgetrequest ()	Return the current Web page request, for example: request
Servletresponsegetresponse ()	Return the response to the current page, for example: Response
Servletconfiggetservletconfig ()	Return the current ServletConfig object for this page, for example: Config
Servletcontextgetservletcontext ()	Return the current execution Environment (context) for this page, for example: application
httpsessiongetsession ()	Return a session with a link to the current page, for example: Sessions

3.PageContext object provides methods to obtain properties

Objectgetattribute (Stringname,intscope)	Return the Name property, scoped to the Property object of scope, with the return type of object
Enumerationgetattributenamesinscope (Intscope)	Return property names of all properties scoped to scope, and the return type is enumeration
Intgetattributesscope (Stringname)	Property range with the return property name named
Voidremoveattribute (Stringname)	To remove a Property object with the property name named
Voidremoveattribute (Stringname,intscope)	Remove Property object with name, range as scope
Voidsetattribute (Stringname,objectvalue,intscope)	Specifies that the Property object has the name, value, and range as scope
Objectfindattribute (Stringname)	Look for property objects in all scopes with property names of name

Nine, exception objects
To use the exception object, you must set it in the page directive. <%@ page iserrorpage= "true"%> to use.
The three methods offered by exception are:

GetMessage ()
Getlocalizedmessage (),
Printstacktrace (Newjava.io.PrintWriter (out)

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