Freemarker Support

• Configure your action to use the freemarker result type
• Property Resolution
• Objects in the Context
• FreeMarker configuration with recent releases
• FreeMarker Whitespace Stripping
• Using struts UI tags - or any JSP Tag Library
• Dynamic attributes support

Freemarker views can be rendered using a result type freemarker.

Configure your action to use the freemarker result type

The freemarker result type is defined in struts-default.xml, so normally you just include it, and define your results to use type="freemarker".

<include file="struts-default.xml"/>
...
<action name="test" class="package.Test">
  <result name="success" type="freemarker">/WEB-INF/views/testView.ftl</result>
</action>
...

Property Resolution

Your action properties are automatically resolved - just like in a velocity view.

for example

${name} will result in stack.findValue("name"), which generally results in action.getName() being executed.

A search process is used to resolve the variable, searching the following scopes in order, until a value is found:

• freemarker variables
• value stack
• request attributes
• session attributes
• servlet context attributes

Objects in the Context

The following variables exist in the FreeMarker views:

• req - the current HttpServletRequest
• res - the current HttpServletResponse
• stack - the current OgnlValueStack
• ognl - the OgnlTool instance
  • This class contains useful methods to execute OGNL expressions against arbitrary objects, and a method to generate a select list using the <s:select/> pattern. (i.e. taking the name of the list property, a listKey and listValue)
• struts - an instance of StrutsBeanWrapper
• action - the current Struts action
• exception - optional the Exception instance, if the view is a JSP exception or Servlet exception view

FreeMarker configuration with recent releases

To configure the freemarker engine that Struts uses, just add a file freemarker.properties to the classpath. The supported properties are those that the Freemarker Configuration object expects - see the Freemarker documentation for these.

default_encoding=ISO-8859-1
template_update_delay=5
locale=no_NO

FreeMarker Whitespace Stripping

Available since Struts 7.2.0

Struts supports automatic whitespace stripping during FreeMarker template compilation. When enabled, this feature removes indentation and trailing whitespace from lines containing only FTL directives, significantly reducing the size of generated HTML output.

This feature is controlled by the struts.freemarker.whitespaceStripping constant:

<constant name="struts.freemarker.whitespaceStripping" value="true" />

Default behavior:

• Enabled by default (true)
• Automatically disabled when struts.devMode is enabled to make debugging easier
• Works transparently with existing templates

Benefits:

• Reduces HTML output size by removing template indentation
• Improves page load times and reduces bandwidth usage
• No changes needed to existing FreeMarker templates
• Automatically disabled in development mode for easier debugging

See also:

• Performance Tuning - FreeMarker Whitespace Stripping
• Compress Tag for runtime HTML compression

Using struts UI tags - or any JSP Tag Library

Freemarker has builtin support for using any JSP taglib. You can use JSP taglibs in FreeMarker even if

• your servlet container has no support for JSP, or
• you didn’t specify the taglib in your web.xml - note how in the example below we refer to the taglib by its webapp-absolute URL, so no configuration in web.xml is needed.

<#assign s=JspTaglibs["/WEB-INF/struts.tld"] />

<@s.form method="'post'" name="'inputform'" action="'save.action'" >
    <@s.hidden name="'id'" />
    <@s.textarea label="'Details'" name="'details'" rows=5 cols=40 />
    <@s.submit value="'Save'" align="center" />
</@s.form>

NOTE: numeric properties for tags MUST be numbers, not strings. as in the rows and cols properties above. If you use cols="40" you will receive an exception. Other than that, the freemarker tag container behaves as you would expect.

Dynamic attributes support

You can specify dynamic attributes with Struts 2 tags like this:

<@s.textfield name="test" dynamicAttributes={"placeholder":"input","foo":"bar"}/>

or like this:

<@s.textfield name="test" placeholder="input" foo="bar"/>

and for both case, it will be parsed into:

<input type="text" name="test" value="" id="test" placeholder="input" foo="bar"/>

You can also use OGNL expressions with dynamic tags like below:

<@s.textfield name="test" placeholder="input" foo="checked: %{bar}"/>

When using attributes with hyphens, use the below syntax (you can also leave the single quotes from false if you want)

<@s.form dynamicAttributes={'data-ajax':'false'}>
  ...
</@s.form>