-JSP: a complement of servlets, easier to write and cause less mistakes than servlets. (You may think JSP is a simple method of servlet at first, but you will see the advantage of JSP later); JSP is translated into servlet(java code) by continer
-Life cycle: jspInit() -> _jspService() -> jspDestroy()
-Elements and Template Data: template is taken and sent directly to a client as it appears on the JSP; elements are not sent directly but interpreted by a JSP container and defines special actions that sould be taken when generating a response, elements are what make JSP dynamic.
-Two dirrerent formats of JSP syntax (will talk later in JSP in XML sntax): normal(original,classic) and xml-compatible
-Scripting elements: directly embedding bits of Java code between blocks of template text; three diferent types availiable : scriptlets, expressions and declarations
-Scriptlets: diretly inserting bits of Java code between chunks of templet text, use the syntax: <% code %> ; scriptlets are great for providing low-level fuctionality such as iteration,loops and condition statements, for many reasons complex scriptlets should be avoided.
-Expressions: provide an easy method of sending out dynamic strings to a client, use the syntax: <%= expression %>
-Declarations: is used like a scriptlet to embed code in a JSP, but outside of _jspService() method (image it has been translated into java code); can be used to declare new methods and global class variables. not thread safe ();use the syntax: <%! declarations %>
-Directives: used to define page attributes, do not send output to a client; use the syntax : <%@ directive {attribute = "value"}* %>; three different directives: page, taglib and include
--Page directive <%@ page %>: provides page-specific information to a JSP container; attributes like language="Java", extends="", import="", session="ture/false" ...
--include directive <%@ include %> (translation-time includes) (see include action will be talked later): include text or code at translation time of a JSP (translation-time includes); syntax: <%@ include file = "relativeURL" %>; a good example to use is including a common header and footer with multiple pages of content(header.jsp, footer.jsp)
--taglib directive <%@ taglib %>: used for custom actions(custom tag libraries); syntax : <%@ taglib uri = "uri" prefix = "prefixOfTag" %> ; note that "uri" attribute value resolves to a location the container understands and the prefix attribute informs a continer what bits of markup are custom actions
-JSP Configuration: directives can only configure one JSP page, to configure more pages, use <jsp-config> element in web.xml. There are two sub elements : <taglib> and <jsp-property-group> (similar to directives, for example very useful children elements <include-prelude> & <include-coda> help you include header&footer automatically)
-JSP Actions: method of linking dynamic code to simple markup that appears in a JSP: two types of actions : standard and custom, : all actions follow the syntax : <prefix:element {attribute="value"}*/> . : a complete action is an xml-compatible tag; : Standard JSP actions are specified by JSP specification and aviliable for use by and JSP continer, Custom actions are created by developers themselves, must be installed with a web application
-Standard JSP Action
--include action: <jsp:include page = "page" />: difference between include directive<%@ include %> (translation-time includes) and include action<jsp:include/> (run-time include) : include action is always current with the source code, while include directive is only current with the resource as it was at the time of tanslation.
--plugin action: <jsp:plugin/>:the plugin action represents one applet that should be embedded in a HTML page
-- forward action: equivalent to the equestDispather.forward(): syntax <jsp:forward url = "relativeURL"/>
-- param action: <jsp:forward/> and<jsp:include/>parameters: <jsp:forward page = "examplePage.jsp"> <jsp:param name = "foo1" value = "bar"/> <jsp:param name = "foo2" value = "<%= foo %>"/> </jsp:forward>
-- other actions: <jsp:useBean /> , <jsp:getProperty /> and <jsp:setProperty />actions all relate to JavaBeans: <jsp:attribute /> , < jsp:body /> , <jsp:doBody /> and <jsp: invoke /> are JSP standard actions exist for use with custom tags
-whitespace Preservation: whitespace is preserved as it appear in a JSP. Formatting is retained by the JSP.
-Attributes: two methods for specifying attributes in JSP elements : run time value and translation time or static values
-comments: <%-- comments --%>
-escape characers: ' is escaped as /'; " is escaped as /"; %> is escaped as %/> <% is escaped as </%
-implicit objects: config, request, response, session, application, pageContext, page, out...: assuming they already exist within a scripting element
-config: web.xml : the only change from servlet is : replacing the previous line <servlet-classes> with <jsp-file>: all of the child elements of the servlet element are still valid
-JSP in XML syntax: the reason to use XML syntax was to keep JSP current with the widespread adoption of XML. XML compliant JSP can be created and manipulated using any existing XML: the JSP XML syntax is not easy to use: HTML used to be the dominant technology on the web but no longer
-XML Documents: JSP actions and custom actions are already in XML-compatible syntax.: scripting elements and directives need to be converted to an XML form.: scripting elements <% %> , <%= %>and <%! %> should be converted into <jsp:scriptlet> , <jsp:expression> and <jsp:declaration> resceptively;: Embedding an expression tag for an attribute value such as : A link to a <a herf = "<jsp:expression>link</jsp:expression>">webside</a> , is not allowed. has to include a specific ncapsulation of the templet text with XML CDATA sections or represent the problematic content with entities.
*reference:Falkner & Jones, Servlet and Java Server Pages,
