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Unformatted text preview: # What is a output comment? Answer: A comment that is sent to the client in the viewable page source.The JSP engine handles an output comment as uninterpreted HTML text, returning the comm ent in the HTML output sent to the client.You can see the comment by viewing the page source from your Web browser. JSP Syntax: � !-- comment [ � %= expression % � ] -- � # What is a Hidden Comment? Answer: A comments that documents the JSP page but is not sent to the client.The JSP engine ignores a hidden comment, and does not process any code within hidde n comment tags.A hidden comment is not sent to the client, either in the display ed JSP page or the HTML page source. The hidden comment is useful when you want to hide or "comment out" part of your JSP page.You can use any characters in the body of the comment except the closi ng --% � combination.If you need to use --% � in your comment, you can escape it by ty ping --%\ � JSP Syntax: � %-- comment --% � Examples: � %@ page language="java" % � � html � � head � � title � A Hidden Comment � /title � � /head � � body � � %-- This comment will not be visible to the colent in the page source --% � � /body � � /html � # What is a Expression? Answer: An expression tag contains a scripting language expression that is evalu ated, converted to a String, and inserted where the expression appears in the JS P file.Because the value of an expression is converted to a String, you can use an expression within text in a JSP file.Like � %= someexpression % � � %= (new java.util.Date()).toLocaleString() % � You cannot use a semicolon to end an expression # What is a Declaration? Answer: A declaration declares one or more variables or methods for use later in the JSP source file.A declaration must contain at least one complete declarativ e statement.You can declare any number of variables or methods within one declar ation tag, as long as they are separated by semicolons.The declaration must be v alid in the scripting language used in the JSP file. � %! somedeclarations % � � %! int i = 0; % � � %! int a, b, c; % � # What is a Scriptlet? Answer: A scriptlet can contain any number of language statements, variable or m ethod declarations, or expressions that are valid in the page scripting language .Within scriptlet tags, you can: * Declare variables or methods to use later in the file. * Write expressions valid in the page scripting language. * Use any of the JSP implicit objects or any object declared with a � jsp:useBe an � tag.You must write plain text, HTML-encoded text, or other JSP tags outside th e scriptlet.Scriptlets are executed at request time, when the JSP engine process es the client request.If the scriptlet produces output, the output is stored in the out object, from which you can display it....
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- Winter '09
- Java Community Process, Enterprise JavaBeans, J2EE application