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JSP directives (Directive) are designed for the JSP engine, and they do not directly produce any visible output, but simply tell the engine how to handle the rest of the JSP page.
Basic syntax format for JSP directives:<%@ directive Property name = "Value"%>
Three instructions:
The full syntax of the page directive defined in the JSP 2.0 specification:
<%@ Page [language="Java"] [extends="Package.class"] [Import="{package.class | package.*}, ..."] [Session="true | false"] [Buffer="None | 8kb | sizekb"] [AutoFlush="true | false"] [IsThreadSafe="true | false"] [Info="text"] [ErrorPage="Relative_url"] [Iserrorpage="true | false"] [ContentType="MimeType [; Charset=characterset]" | "text/html; charset=iso-8859-1"] [pageencoding="CharacterSet | Iso-8859-1"] [iselignored="true | false" ] %>
For example:
<%@ Language= "java " page import=" java.util.*,java.io.*,java.sql.* " Span style= "COLOR: #ff0000" > errorpage = "/errorpage/error.jsp " Pageencoding= "utf-8" iserrorpage= "true" %>
In general, exception objects are not available in JSP pages, only the Iserrorpage property of the page directive is set to "true"(the default is False) To explicitly declare that a JSP page is an error-handling page before the exception object can be used in a JSP page.
Use the <error-page> tab in Web. XML to set up error handling pages for your entire application:<?XML version= "1.0" encoding= "UTF-8"?><Web-appversion= "3.0"xmlns= "Http://java.sun.com/xml/ns/javaee"Xmlns:xsi= "Http://www.w3.org/2001/XMLSchema-instance"xsi:schemalocation= "Http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"> <Display-name></Display-name> <welcome-file-list> <Welcome-file>index.jsp</Welcome-file> </welcome-file-list> <!--processing page for 500 error - <Error-page> <Error-code>4500</Error-code> < Location>/errorpage/500error.jsp</ Location> </Error-page> </Web-app>
500error.jsp ( custom error page of size preferably more than 1024bytes, otherwise ie may not jump )
<%@ Page Language="Java"Import="java.util.*"pageencoding="UTF-8"%><HTML> <Head> <title>500 (server error) error friendly tip page</title> <!--Auto Jump back to page after 3 seconds - <Metahttp-equiv= "Refresh"content= "3;url=${pagecontext.request.contextpath}/index.jsp"> </Head> <Body> <imgalt= "Sorry, the server is wrong, please contact the administrator to resolve!" "src= "${pagecontext.request.contextpath}/img/500error.png"/><BR/>3 seconds after the automatic jump back to the page, if there is no jump, please click<ahref= "${pagecontext.request.contextpath}/index.jsp">Over here</a> </Body></HTML>Ii. include directives
Syntax:<%@ include file= "Relativeurl"%>, where the file property is used to specify the path to the introduced files. The path begins with "/" and represents the current web app.
<j@include > statements that contain other file contents to their own pages are called static inclusions.
The <jsp:include> directive is dynamically included , and if the contained page is a JSP, it is processed before the result is included, and if it contains a non-*.jsp file, it simply contains the contents of the file statically. Functions similar to @include
Iii. taglib directive<%@ taglib uri= "uritotaglibrary" prefix= "TagPrefix"%>
<% @ taglib%> directive declares that this JSP file uses a custom label, references the tag library, and also specifies the prefix of their tag
JSP Learning (ii) JSP directives
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