SE452: JSP elements [13/16]

Expressions

• <%= expression %>
• the value as a String is printed out to the JspWriter
• Can also be written in XML sytax as <jsp:expression> expression </jsp:expression>
• Think of it as out.println(expression)
• Example:Current Time: <%= new java.util.Date() %>

Scriptlets

• <% code %>
• Can also be written in XML sytax as <jsp:scriptlet> code </jsp:scriptlet>
• Run in the _jspService method
• Can contain any Java code
• Has access to the same predefined variables as expressions
• Can make parts of a JSP conditional

Declarations

• <%! code %>
• Can also be written in XML sytax as <jsp:declaration> code </jsp:declaration>
• Inserted in the body of the servlet, outside of any existing code
• Declares variables accessible by all threads, the declaration is placed outside the _jspService method.
• Do not generate any output

Comments

• HTML Comments (will be in the source sent to the client)
• Ex:<!-- this goes -->
• JSP Comments (only put in Java source, stays on server)
• Ex:<%-- JSP comment --%>

Escaping in JSPs

In scripting elements

• A literal %> is quoted as %\>

In template text

• A literal <% is quoted as <\%

In attributes

• A ' is quoted as \'
• A " is quoted as \"
• A \ is quoted as \\
• A %> is quoted as %\>
• A <% is quoted as %\>