JSP Reference
From Javapedia
Contents |
[edit] JSP Directives
- include – The include directive informs the JSP compiler to include a complete file into the current file. It is as if the contents of the included file were pasted directly into the original file. Included files sometimes have the extension "jspf" (for JSP Fragment):
<%@ include file="header.jspf" %>
- page – There are several options to the page directive.
- import results in a Java import statement being inserted into the resulting file
- contentType specifies the content that is generated. This should be used if HTML is not used or if the character set is not the default character set.
- errorPage indicates the page that will be shown if an exception occurs while processing the HTTP request.
- isErrorPage if set to true, it indicates that this is the error page.
- isThreadSafe indicates if the resulting servlet is thread safe.
<%@ page import="java.util.*" %> //example import
<%@ page contentType="text/html" %> //example contentType
<%@ page isErrorPage=false %> //example for non error page
<%@ page isThreadSafe=true %> //example for a thread safe JSP
- taglib – The taglib directive indicates that a JSP tag library is to be used. The directive requires that a prefix be specified (much like a namespace in C++) and the URI for the tag library description.
<%@ taglib prefix="myprefix" uri="taglib/mytag.tld" %>
[edit] JSP Scripting Elements
[edit] Implicit Objects
- out – The JSPWriter used to write the data to the response stream.
- page – The servlet itself.
- pageContext – A PageContext instance that contains data associated with the whole page. A given HTML page may be passed among multiple JSPs.
- request – The HttpServletRequest object that provides HTTP request information.
- response – The HTTP response object.
- session – The HTTP session object that can be used to track information about a user from one request to another.
- config – Provides servlet configuration data.
- application – Data shared by all JSPs and servlets in the application.
- exception – Exceptions not caught by application code.
[edit] Scripting Elements
- A declaration tag places a variable definition inside the body of the java servlet class. Static data members may be defined as well.
<%! int serverInstanceVariable = 1; %>
- A scriptlet tag places the contained statements inside the _jspService() method of the java servlet class.
<% int localStackBasedVariable = 1;
out.println(localStackBasedVariable); %>
- An expression tag places an expression to be evaluated inside the java servlet class. Expressions should not be terminated with a semi-colon .
<%= "expanded inline data " + 1 %>
[edit] JSP Actions
- jsp:include Similar to a subroutine, the Java servlet temporarily hands the request and response off to the specified JavaServer Page. Control will then return to the current JSP, once the other JSP has finished. Using this, JSP code will be shared between multiple other JSPs, rather than duplicated.
- jsp:param Can be used inside a jsp:include, jsp:forward or jsp:params block. Specifies a parameter that will be added to the request's current parameters.
- jsp:forward Used to hand off the request and response to another JSP or servlet. Control will never return to the current JSP.
- jsp:plugin Older versions of Netscape Navigator and Internet Explorer used different tags to embed an applet. This action generates the browser specific tag needed to include an applet.
- jsp:fallback The content to show if the browser does not support applets.
- jsp:getProperty Gets a property from the specified JavaBean.
- jsp:setProperty Sets a property in the specified JavaBean.
- jsp:useBean Creates or re-uses a JavaBean available to the JSP page.
