Nine built-in JSP objects [Details]

① Out-javax. servlet. jsp. jspwriter <br/> The out object is used to output the result to the webpage. </P> <p> method: <br/> 1. Void clear (); <br/> clear the content of the output buffer, but not output to the client. </P> <p> 2. Void clearbuffer (); <br/> clear the content of the output buffer and output it to the client. </P> <p> 3. Void close (); <br/> close the output stream and clear all content. </P> <p> 4. Void flush (); <br/> output data in the buffer. </P> <p> 5. Int getbuffersize (); <br/> obtains the current buffer size in KB. </P> <p> 6. Int getremaining (); <br/> obtains the unoccupied space in the buffer in KB. </P> <p> 7. boolean isautoflush (); <br/> whether to automatically refresh the buffer. </P> <p> 8. Void newline (); <br/> output a line feed character. </P> <p> 9. void print (Boolean B); <br/> void print (char C); <br/> void print (char [] S ); <br/> void print (double D); <br/> void print (float F); <br/> void print (int I ); <br/> void print (long l); <br/> void print (Object OBJ); <br/> void print (string S ); <br/> output data of the specified type to the HTTP stream without line breaks. </P> <p> 10. void println (Boolean B); <br/> void println (char C); <br/> void println (char [] S ); <br/> void println (double D); <br/> void println (float F); <br/> void println (int I ); <br/> void println (long l); <br/> void println (Object OBJ); <br/> void println (string S ); <br/> output data of the specified type to the HTTP stream and a line break. </P> <p> 11. appendable append (char C); <br/> appendable append (charsequence cxq, int start, int end); <br/> appendable append (charsequence cxq ); <br/> Add a character or an object that implements the charsequence interface to the end of the output stream. </P> <p> member: <br/> int default_buffer = 0-default buffer size <br/> int no_buffer =-1-whether the writer is in the buffer output state <br/> int unbounded_buffer =-2-whether to limit buffer size </P> <p> ② request-javax. servlet. HTTP. httpservletrequest <br/> the request object contains information about all requests, such as the request source, header, cookies, and request-related parameter values. </P> <p> method: <br/> 1. Object getattribute (string name); <br/> return the property value specified by name. If the property does not exist, null is returned. </P> <p> 2. Enumeration getattributenames (); <br/> return a set of all attribute names of the request object. </P> <p> 3. String getauthtype (); <br/> return the name of the authentication method used to protect the servlet. If not, null is returned. </P> <p> 4. String getcharacterencoding (); <br/> return the character encoding method in the request, which can be set in the response object. </P> <p> 5. Int getcontentlength (); <br/> return the length of the Request body. If the length cannot be determined, return-1. You can set it in response. </P> <p> 6. String getcontenttype (); <br/> return the content type defined in response. </P> <p> 7. String getcontentpath (); <br/> return the Request Path. </P> <p> 8. Cookie [] getcookies (); <br/> return an array of all cookies on the client. </P> <p> 9. Enumeration getheadernames (); <br/> Returns a set of names of all HTTP headers. </P> <p> 10. Enumeration getheaders (string name); <br/> return a set of all values of the specified HTTP header. </P> <p> 11. String getheader (string name); <br/> the HTTP header with the specified name is returned. </P> <p> 12. Long getdateheader (string name); <br/> return the information of the data-Type HTTP header with the specified name. </P> <p> 13. Int getintheader (string name); <br/> return the information of the HTTP header of the int type with the specified name. </P> <p> 14. servletinputstream getinputstream (); <br/> return the input stream of the request. </P> <p> 15. locale getlocale (); <br/> return the locale object of the current page, which can be set in response. </P> <p> 16. Enumeration getlocales (); <br/> return the set of all locale objects in the request. </P> <p> 17. String getlocalname (); <br/> obtain the server host name in response to the request. </P> <p> 18. String getlocaladdr (); <br/> obtain the server address of the Response Request. </P> <p> 19. int getlocalport (); <br/> get the server port responding to the request </P> <p> 20. string getmethod (); <br/> obtain the methods (get and post) that the client sends a request to the server ). </P> <p> 21. String getparameter (string name); <br/> obtain the parameter value sent from the client to the server. </P> <p> 22. Map getparametermap (); <br/> This method returns a map object containing all the parameters in the request. </P> <p> 23. Enumeration getparameternames (); <br/> return a set of all parameters in the request. </P> <p> 24. String [] getparametervalues (string name); <br/> obtain all values of the specified parameter in the request. </P> <p> 25. String getquerystring (); <br/> return the parameter string passed by the get method. This method does not parse individual parameters. </P> <p> 26. String getpathinfo (); <br/> retrieve the additional information in the request between servletpath and querystring. </P> <p> 27. String getpathtranslated (); <br/> return the actual path of the path information obtained using the getpathinfo () method. </P> <p> 28. String getprotocol (); <br/> return the protocol used by the request. It can be http1.1 or http1.0. </P> <p> 29. bufferedreader getreader (); <br/> the reader object corresponding to the input stream of the request is returned. This method and the getinputstream () method can only be called on one page. </P> <p> 30. String getremoteaddr (); <br/> obtain the IP address of the client sending the request. </P> <p> 31. string getremotehost (); <br/> obtain the client host name that sends the request </P> <p> 32. string getremoteuser (); <br/> the user name verified by the client is returned. If the user name is not verified, null is returned. </P> <p> 33. Int getremoteport (); <br/> return the client host port sending the request. </P> <p> 34. String getrealpath (string path); <br/> returns the physical path of the given virtual path. </P> <p> 35. requestdispatcher getrequestdispatcher (string path); <br/> Generate a resource based on the given path to process the adapter object. </P> <p> 36. String getrequestedsessionid (); <br/> return the ID of the Request session. </P> <p> 37. String requesturi (); <br/> return the client address that sends the request, but does not include the request parameter string. </P> <p> 38. stringbuffer getrequesturi (); <br/> return the server address of the Response Request </P> <p> 39. string getscheme (); <br/> obtain the protocol name. The default value is HTTP. </P> <p> 40. String getservername (); <br/> return the name of the server responding to the request. </P> <p> 41. String getservletpath (); <br/> obtain the path of the script file requested by the client. </P> <p> 42. Int getserverport (); <br/> obtain the server host port number that responds to the request. </P> <p> 43. Void removeattribute (string name); <br/> Delete the attribute of the specified name in the attribute list. </P> <p> 44. Void setattribute (string name, object value); <br/> Add/delete a specified attribute in the attribute list. </P> <p> 45. Void setcharacterencoding (string name); <br/> set the character encoding format of the request. </P> <p> 46. httpsession getsession (); <br/> httpsession getsession (Boolean create); <br/> get the session. If create is set to true, create a session without a session. </P> <p> 47. boolean isrequestedsessionidfromcookie (); <br/> check whether the request session ID is passed through cookies. </P> <p> 48. boolean isrequestedsessionidfromurl (); <br/> check whether the request session ID is passed through a URL. </P> <p> 49. boolean isrequestedsessionidvalid (); <br/> check whether the request session ID is still valid. </P> <p> 50. boolean issecure (); <br/> check whether the request uses a secure link, if https or so. </P> <p> 51. boolean isuserinrole (string role); <br/> check whether the verified user is in the role specified by role. </P> <p> 52. Principal getuserprincipal (); <br/> A java. Security. principal object containing the user's login name is returned. </P> <p> member: <br/> string basic_auth = "Basic"-<br/> string client_cert_auth = "client_cert"-<br/> string digest_auth = "Digest"-<br/> string form_auth = "form"-</P> <p> ③ response-javax. servlet. HTTP. httpservletresponse <br/> the response object mainly transmits the results processed by the JSP Container Back to the client. </P> <p> method: <br/> 1. Void addcookie (cookie); <br/> Add a cookie object to save client information. </P> <p> 2. Void adddateheader (string name, long value); <br/> Add a date-Type HTTP header that overwrites the HTTP header with the same name. </P> <p> 3. Void addheader (string name, string value); <br/> Add an HTTP header to overwrite the old HTTP header with the same name. </P> <p> 4. Void addintheader (string name, int value); <br/> Add an integer HTTP header to overwrite the old HTTP header with the same name. </P> <p> 5. boolean containsheader (string name); <br/> determine whether the specified HTTP header exists. </P> <p> 6. String encoderedirecturl (string URL); <br/> encode the URL used by sendredirect. </P> <p> 7. String encodeurl (string URL); <br/> encode the URL and return the URL containing the session ID. </P> <p> 8. Void flushbuffer (); <br/> force the content of the current buffer zone to be sent to the client. </P> <p> 9. Int getbuffersize (); <br/> obtain the buffer size in KB. </P> <p> 10. String getcharacterencoding (); <br/> obtain the character encoding format of the response. </P> <p> 11. String getcontenttype (); <br/> obtain the response type. </P> <p> 12. locale getlocale (); <br/> obtain the response locale object. </P> <p> 13. servletoutputstream getoutputstream (); <br/> return the output stream object of the client. </P> <p> 14. printwriter getwriter (); <br/> obtain the writer object corresponding to the output stream. </P> <p> 15. boolean iscommitted (); <br/> determine whether the server has output data to the client. </P> <p> 16. Void reset (); <br/> clear all content in the buffer. </P> <p> 17. Void resetbuffer (); <br/> all content in the buffer, but the HTTP header and status information are retained. </P> <p> 18. void senderror (int xc, string MSG); <br/> void senderror (int xc); <br/> sending error, including status code and error message. </P> <p> 19. Void sendredirect (string locationg); <br/> send the response to another location for processing. </P> <p> 20. Void setbuffersize (INT size); <br/> set the buffer size in KB. </P> <p> 21. Void setcharacterencoding (string charset); <br/> set the character encoding format used by the response. </P> <p> 22. Void setcontentlength (INT length); <br/> set the length of the response body. </P> <p> 23. Void setcontenttype (string type); <br/> set the response type. </P> <p> 24. Void setdateheader (string name, long value); <br/> set the value of the HTTP header of the data type with the specified name. </P> <p> 25. Void setheader (string name, string value); <br/> set the HTTP header value of the specified name. </P> <p> 26. Void setintheader (string name, int value); <br/> set the HTTP header value of the int type of the specified name. </P> <p> 27. Void setstatus (int xc); <br/> set the response status code. The new value overwrites the current value. </P> <p> member (HTTP status code ): <br/> int SC _continue = 100 int SC _switching_protocols = 101 <br/> int SC _ OK = 200 int SC _non_authoritative_information = 203 <br/> int SC _accepted = 202 int SC _created = 201 <br/> int SC _no_content = 204 int SC _reset_content = 205 <br/> int SC _partial_content = 206 int SC _multiple_choices = 300 <br/> int Limit = 301 int Limit = 302 <br/> int SC _found = 30 2 int SC _see_other = 303 <br/> int SC _not_modified = 304 int SC _use_proxy = 305 <br/> int response = 307 int SC _bad_request = 400 <br/> int SC _unauthorized = 401 int response = 402 <br/> int SC _forbidden = 403 int SC _not_found = 404 <br/> int SC _method_not_allowed = 405 int SC _not_acceptable = 406 <br/> int Limit = 407 int SC _request_timeout = 408 <br/> Int SC _conflict = 409 int SC _gone = 410 <br/> int SC _length_required = 411 int SC _precondition_failed = 412 <br/> int Limit = 413 int Limit = 414 <br/> int Limit = 415 int SC _requested_range_not_satisfiable = 416 <br/> int SC _expectation_failed = 417 int SC _internal_server_error = 500 <br/> int SC _not_implemented = 501 int SC _bad_gateway = 502 <Br/> int SC _service_unavailable = 503 int SC _gateway_timeout = 504 <br/> int SC _http_version_not_supported = 505 </P> <p> ④ session-javax. servlet. HTTP. httpsession <br/> the session object indicates the session Status of individual users, which is used to identify each user. </P> <p> method: <br/> 1. Object getattribute (string name); <br/> obtain the session attribute value associated with the specified name. </P> <p> 2. Enumeration getattributenames (); <br/> obtains the set of all attributes in the session. </P> <p> 3. Long getcreationtime (); <br/> return the session creation time. The minimum unit is 1‰ seconds. </P> <p> 4. String GETID (); <br/> obtain the session ID. </P> <p> 5. Long getlastaccessedtime (); <br/> return the last access time of the client associated with the current session, counted from, in milliseconds. </P> <p> 6. Int getmaxinactiveinterval (INT interval); <br/> the total returned time, in seconds, indicates the session validity period (the session is not active ). -1 indicates that it never expires. </P> <p> 7. servletcontext getservletcontext (); <br/> an instance of the servletcontext object corresponding to the JSP page is returned. </P> <p> 8. httpsessioncontext getsessioncontext (); </P> <p> 9. object getvalue (string name); <br/> get the session variable value of the specified name, which is not recommended. </P> <p> 10. String [] getvaluenames (); <br/> the set of names of all session variables is not recommended. </P> <p> 11. Void invalidate (); <br/> destroy the session object. </P> <p> 12. boolean isnew (); <br/> checks whether a session is generated by the server, but is not used by the client. </P> <p> 13. Void pubvalue (string name, object value); <br/> it is not recommended to add a session variable. </P> <p> 14. Void removevalue (string name); <br/> it is not recommended to remove the value of a session variable. </P> <p> 15. Void setattribute (string name, string value); <br/> set the session attribute value of the specified name. </P> <p> 16. Void setmaxinactiveinterval (INT interval); <br/> set the session validity period. </P> <p> 17. Void removeattribute (string name); <br/> remove the session attribute of the specified name. </P> <p> ⑤ pagecontext-javax. servlet. jsp. pagecontext <br/> the pagecontext object stores information about the JSP page, such as attributes and built-in objects. </P> <p> method: <br/> 1. void setattribute (string name, object value, int scope); <br/> void setattribute (string name, object value); <br/> set attributes within the specified sharing range. </P> <p> 2. object getattribute (string name, int scope); <br/> Object getattribute (string name); <br/> get the attribute value named name in the specified shared range. </P> <p> 3. Object findattribute (string name); <br/> Search for named properties by PAGE, request, session, and application sharing range. </P> <p> 4. void removeattribute (string name, int scope); <br/> void removeattribute (string name); <br/> remove attributes with the specified name and shared range. </P> <p> 5. Void forward (string URL); <br/> navigate the page to the specified URL. </P> <p> 6. Enumeration getattributenamesscope (INT scope); <br/> obtains a set of all attribute names within the specified shared range. </P> <p> 7. Int getattributescope (string name); <br/> get the sharing range of the specified attribute. </P> <p> 8. errordata geterrordate (); <br/> get the errordata object on the page. </P> <p> 9. Exception getexception (); <br/> get the exception object of the page. </P> <p> 10. expressionevaluator getexpressionevaluator (); <br/> obtain the expressionevaluator object on the page. </P> <p> 11. jspwriter getout (); <br/> get the out object of the page. </P> <p> 12. Object getpage (); <br/> obtain the Page Object of the page. </P> <p> 13. servletrequest getrequest (); <br/> obtain the request object on the page. </P> <p> 14. servletresponse getresponse (); <br/> get the page's response object. </P> <p> 15. servletconfig getconfig (); <br/> get the config object of the page. </P> <p> 16. servletcontext getservletcontext (); <br/> obtain the servletcontext object of the page. </P> <p> 17. httpsession getsession (); <br/> obtain the session object on the page. </P> <p> 18. variableresolver getvariableresolver (); <br/> obtain the variableresolver object on the page. </P> <p> 19. void include (string URL, Boolean flush); <br/> void include (string URL); <br/> includes other resources and specifies whether to automatically refresh. </P> <p> 20. Void release (); <br/> Reset the internal status of pagecontext and release all internal references. </P> <p> 21. void initialize (servlet, servletrequest request, servletresponse response, <br/> string errorpageurl, Boolean needsession, int buffersize, Boolean autoflush); <br/> initialize uninitialized pagecontext objects. </P> <p> 22. bodycontext pushbody (); <br/> bodycontext pushbody (writer); <br/> saves the current out object and updates the out object in the page range of pagecontext. </P> <p> 23. jspwrite popbody (); <br/> retrieve the out object saved by the pushbody () method. </P> <p> 24. void handlepageexception (exception E); <br/> void handlepageexception (thrwoable T); </P> <p> member: <br/> int page_scope = 1-page sharing range <br/> int request_scope = 2-request sharing range <br/> int session_scope = 3-session sharing range <br/> int application_scope = 4-application sharing scope <br/> string page = "javax. servlet. JSP. jsppage "<br/> string pagecontext =" javax. servlet. JSP. jsppagecontext "<br/> string request =" javax. servle T. JSP. jsprequest "<br/> string response =" javax. servlet. JSP. jspresponse "<br/> string Config =" javax. servlet. JSP. jspconfig "<br/> string session =" javax. servlet. JSP. jspsession "<br/> string out =" javax. servlet. JSP. jspout "<br/> string application =" javax. servlet. JSP. jspapplication "<br/> string exception =" javax. servlet. JSP. jspexception "</P> <p> ⑥ application-javax. servlet. servletcontext <br/> app Lication is mainly used to get or change servlet settings. </P> <p> method: <br/> 1. Object getattribute (string name); <br/> the application attribute specified by name is returned. </P> <p> 2. Enumeration getattributes (); <br/> all application attributes are returned. </P> <p> 3. servletcontext getcontext (string uripath); <br/> obtain the servletcontext object of the current application. </P> <p> 4. String getinitparameter (string name); <br/> return the initial value of the application attribute specified by name. </P> <p> 5. Enumeration getinitparameters (); <br/> return the set of initial values of all application attributes. </P> <p> 6. Int getmajorversion (); <br/> the version number of the servlet API supported by the servlet container is returned. </P> <p> 7. String getmimetype (string file); <br/> the type of the specified file is returned. If the file type is unknown, null is returned. It is generally "text/html" and "image/GIF ". </P> <p> 8. Int getminorversion (); <br/> the minor version of the servlet API supported by the servlet container is returned. </P> <p> 9. String getrealpath (string path); <br/> returns the physical path corresponding to the given virtual path. </P> <p> 10. requestdispatcher getnameddispatcher (string name); <br/> an instance of the requestdispatcher object is returned for the servlet object with the specified name. </P> <p> 11. requestdispatcher getrequestdispatcher (string path); <br/> an instance of the requestdispatcher object is returned. </P> <p> 12. url getresource (string path); <br/> return a URL object instance corresponding to the specified resource path. The parameter must start. </P> <p> 13. inputstream getresourceasstream (string path); <br/> Returns An inputstream object instance of the resource at the specified position of the path. </P> <p> 14. Set getresourcepaths (string path); <br/> return the set of all resource paths stored in the Web-app. </P> <p> 15. String getserverinfo (); <br/> obtain the application server version. </P> <p> 16. servlet getservlet (string name); <br/> retrieve the servlet with the specified name in servletcontext. </P> <p> 17. Enumeration getservlets (); <br/> return the set of all servlets in servletcontext. </P> <p> 18. String getservletcontextname (); <br/> return the name of the Web application. </P> <p> 19. Enumeration getservletcontextnames (); <br/> return the name set of all servlets in servletcontext. </P> <p> 20. void log (exception ex, string MSG); <br/> void log (string MSG, throwable T); <br/> void log (string MSG ); <br/> write the specified information to the servlet log file. </P> <p> 21. Void removeattribute (string name); <br/> remove the application attribute of the specified name. </P> <p> 22. Void setattribute (string name, object value); <br/> set the value of the specified application attribute. </P> <p> 7config-javax. servlet. servletconfig <br/> the config object is used to store the initial servlet data structure. </P> <p> method: <br/> 1. String getinitparameter (string name); <br/> return the value of the parameter promoted by name. </P> <p> 2. Enumeration getinitparameters (); <br/> return a set of names of all the prompt parameters in the JSP. </P> <p> 3. servletcontext getcontext (); <br/> the servlet context of the performer is returned. </P> <p> 4. String getservletname (); <br/> the servlet name is returned. </P> <p> Except exception-java. lang. throwable <br/> error object. The exception object can be used on this page only after iserrorpage = "true" is specified in the page command of the JSP page. </P> <p> method: <br/> 1. throwable fillinstacktrace (); <br/> record the current stack information to the exception object. </P> <p> 2. String getlocalizedmessage (); <br/> obtain the error message of the local language. </P> <p> 3. String getmessage () <br/> get the error message. </P> <p> 4. stacktrackelement [] getstacktrace (); <br/> return the call stack track information recorded in the object. </P> <p> 5. throwable initcause (throwable cause); <br/> nest another exception object into the current exception object. </P> <p> 6. throwable getcause (); <br/> retrieve exceptions nested in the current exception object. </P> <p> 7. void printstacktrace (); <br/> void printstacktrace (printstream S); <br/> void printstacktrace (printwriter S); <br/> prints throwable and its call stack trace information. </P> <p> 8. Void setstacktrace (stacktraceelement [] stacktrace) <br/> sets the call stack trace information of an object. </P> <p> analyze page-javax. servlet. JSP. httpjsppage <br/> the Page Object represents the JSP object itself, or the compiled servlet object. <br/> it can be used (javax. servlet. JSP. httpjsppage) page.