Template Code Generator Part 2 : FreeMarker

In my previous post, I covered Apache Velocity, Eclipse JET/JET2.
I got a suggestion to look the framework FreeMarker.

FreeMarker look like Velocity. You can even find converters : Velocity -> FreeMarker.
I'll describe in this part how to create the same output but using FreeMarker.

Take a look at the generate method.

SampleFreeMarker.java


  public void generate() {

    try {
      Configuration cfg = new Configuration();
      
      cfg.setObjectWrapper(ObjectWrapper.BEANS_WRAPPER);

      Template tpl = cfg.getTemplate("./templates/GalleryTemplateFreeMarker.ftl");
      OutputStreamWriter output = new OutputStreamWriter(System.out);
      
      Map root = new HashMap();
      
      root.put("list", mediaFileList);
      
      tpl.process(root, output);
      
    } catch (Exception e) {
      s_logger.error("generate", e);
    }

  }

Let's compare to the Velocity implementation.

SampleVelocity.java


  public void generate() {

    try {
      Velocity.init();

      VelocityContext context = new VelocityContext();
      context.put("list", mediaFileList);

      Template template = Velocity.getTemplate("./templates/GalleryTemplateVelocity.vm");

      BufferedWriter writer = writer = new BufferedWriter(new OutputStreamWriter(System.out));

      if (template != null)
        template.merge(context, writer);

      /*
       * flush and cleanup
       */

      writer.flush();
      writer.close();
      
    } catch (Exception e) {
      s_logger.error("generate", e);
    }

  }

The main difference is with FreeMarker you need to create a root HashMap and put the objects in it.
With Velocity you put the objects within the context.

Now see the FreeMarker template.


<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" 
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> 
 
 <html> 
  <head>
    <!-- include the required JavaScript file --> 
  </head>
 
 <body>
  <div align="center">
    <table width="80%">
<#assign maxItembyRow = 2>
<#assign index = 0>
<#assign count = 0>
<#assign newLine = true>
<#foreach mediaFile in list>
  <#if newLine>
      <tr>
  <#assign newLine = false>
  </#if>
        <td>
            <a href="/${mediaFile.name}" id="player${count}">
            </a>
        </td>
  <#if index < maxItembyRow-1>        
    <#assign index = index + 1>
  <#else>
    <#assign index = 0>
    <#assign newLine = true>
  </#if>
  <#if newLine>
      </tr>
  </#if>
  <#assign count = count + 1>
</#foreach>
    </tr>
  </table>
  </div>
  </body>
</html>

It's almost the same as Velocity except that the syntax change a little.


<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" 
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> 
 
 <html> 
  <head>
    <!-- include the required JavaScript file --> 
  </head>
 
 <body>
  <div align="center">
    <table width="80%">
#set( $maxItembyRow = 2)
#set( $index = 0)
#set( $newLine = true)
#foreach( $mediaFile in $list )
#if( $newLine )
    <tr>
#set( $newLine = false)
#end
#if( $index<$maxItembyRow )
        <td><a href="/$mediaFile.name" id="player$velocityCount"> 
            </a>
        </td>
#set($index = $index+1)
#else
#set($index = 0)
#set( $newLine = true)
#end
#end
    </tr>
  </table>
  </div>
  </body>
</html>

What I didn't like about FreeMarker is the lack of documentation.
There had good javadoc, but something you need more than that like "real life" samples.
The source code can be downloaded here.