j2ee: JSP Actions [14/20]

Special tags that affect the out stream and use, modify, or create objects

Standard Actions

        <jsp:forward>
        <jsp:include>
        <jsp:param>
        <jsp:plugin>
        <jsp:params>
        <jsp:fallback>
        <jsp:useBean>
        <jsp:getProperty>
        <jsp:setProperty>
        
        <jsp:attribute>
        <jsp:element>
        <jsp:body>
        <jsp:invoke>
        <jsp:doBody>
        <jsp:text>
        <jsp:output>
        

The last 7 will be discussed once we learn about custom tag libraries

Custom actions: created with tag libraries

forward

Syntax : <jsp:forward page="relativeURLspec" />

• Allows the runtime dispatch of the request to one of the following in the same context as the current page:
  • static resource (html) (for GET requests)
  • A JSP
  • A Java servlet
• Terminates the execution of the current page
• Example : <% String dest = "/location/"+someValue; %> <jsp:forward page='<%= dest %>' />

include

Syntax:

        <jsp:include page="urlSpec" flush="true|false"/>
        

and

        <jsp:include page="urlSpec" flush="true|false">
            { <jsp:param .... /> }*
        </jsp:include>
        

Include a resource at request time, or a request with parameters

param

Used with include and foward and params elements

Syntax:

        <jsp:param name="name" value="value" />
        

plugin

replaces the tag with either an <object> or <embed> tag as needed by the user agent to display an applet or similar plugin properly. The params and fallback actions are used to provide for passing parameters to the plugin and providing feedback to the user if the plugin failed to load.

Example:

        <jsp:plugin type=applet code="Molecule.class" 
		codebase="/html" >
            <jsp:params>
		<jsp:param
			name="molecule"
			value="molecules/benzene.mol"/>
            </jsp:params>
            <jsp:fallback>
		<p> unable to start plugin </p>
            </jsp:fallback>
        </jsp:plugin>