JSP built-in objects

Application:

Let JSP, servlet share data: Application.setattribute (string name,object value) Set share property, Application.getatrribute (string name) Get the value of a shared property

Get web App configuration parameters

Config: current JSP configuration information

Exception: only valid on exception handling pages

Out: Page output stream

PageContext: Access to shared data between JSPs, including page, request, session, application range data

Set share properties: SetAttribute (String name, Object value,int scope)

GetAttribute (String name,int scope), scope has a value range of four, corresponding to page, request, session, application:

Page:PageContext.PAGE_SCOPE

Request:PageContext.REQUEST_SCOPE

Session:PageContext.SESSION_SCOPE

Application:PageContext.APPLICATION_SCOPE

Gets the range value of the property: Pagecontext.getattributesscope (String name)

Request: Encapsulates one user request per object

1. Can get the requested parameter, request header: (POST method submission)

Gets the name of the request header:

Enumeration<string> Headernames=request.getheadernames ();  　　　　　　while (Headernames.hasmoreelements ()) {String headername=headernames.nextelement (); 　　　　Out.println (headername+ "--" +request.getheader (headername) + "<br/>"); }

Get the data submitted by the form form:

String name=request.getparameter ("name");//name, color is the Name property of each data in form forms

String[] Color=request.getparametervalues ("color");//Get method when request parameter has multiple values

Get method commits: pass parameters as strings and pass parameters less URL way to pass parameters, parse strings with Chinese parameters: (Problem not resolved) string rawquerystr = Request.getquerystring ();  String querystr = Java.net.URLDecoder.decode (Rawquerystr, "utf-8");  String[] Parampairs=querystr2.split ("&");      for (String parampair:parampairs) {string[] namevalue=parampair.split ("=");         OUT.PRINTLN (namevalue[0]+ "parameter value:" +namevalue[1]+ "

String mytext = Java.net.URLEncoder.encode ("China", "utf-8"); String mytext2 = Java.net.URLDecoder.decode (MyText, "Utf-8");//mytext result is garbled and mytext2 result is "China"

2. Parameters for Operation request Range: SetAttribute (String name,object value); GetAttribute (String name);

3. Execute forward or include: (path path must start with a slash) Getrequestdispatcher (String path). Include (Request,respose); Getrequestdispatcher (String Path). Forward (Request,response);

Response: Generate a non-character response, redirect, increase Coolie Redirect, generate a second request, and the original requested parameter, request scope properties are all lost increase cookie:string name=request.getparameter ("  Name ");  Cookie C = new Cookie ("Usename", name); C.setmaxage (24*3600);//Set Cookie to 24 hours Response.addcookie (c);//Add Cookie Object

Read the Cookie array: cookie[] cookies = request.getcookies ();      for (Cookie c:cookies) {if (C.getname (). Equals ("Usename")) {Out.println (C.getvalue ()); }  }

Session: This object represents a user session SetAttribute (String name,object value); GetAttribute (String name);

JSP built-in objects