You need to find a templating engine that supports number formatting, date formatting, and comparison of double values. In addition, you are looking for a templating engine that gives you more control over whitespace and line breaks.

Use FreeMarker, a templating engine with a large built-in feature set that includes support for date and number formatting and intelligent handling of whitespace. The following FreeMarker template creates a summary report for a college course:

<#assign student = enrollment.student >
<#assign course = enrollment.course >
<#assign exams = enrollment.exams >
<#-- This macro assigns a variable named final -->
<@final exams=exams/>    

${student.firstName} ${student.lastName},

Here is a summary of your performance in ${course.dept} ${course.num} 
${course.name}.  

Class:         ${course.name}
Professor:     ${course.professor}
Section:       ${enrollment.section?string("000")}

Exam, Date, Score, Weight, Grade
-----------------------------------------------
<#list exams as exam>
  <@compress single_line=true>
    <#assign score = exam.score >
    ${exam.name}, 
    ${exam.date?date?string.short}, 
    #{exam.score; m1M1}, 
    ${exam.weight},
    <@letter score=score/>        
  </@compress>
  
</#list>

Final Grade:  ${final; m1M1} <@letter score=final/>        
Your final grade has been submitted to the Registrar.  

<#macro final exams>
    <#local num = 0>
    <#local dem = 0>
    <#list exams as exam>
        <#local num = num + (exam.score * exam.weight)/>
        <#local dem = dem + exam.weight>
    </#list>
    <#assign final = num / dem>
</#macro>

<#macro letter score>
    <#if (score >= 90)> A
    <#elseif (score >= 80)> B
    <#elseif (score >= 70)> C
    <#elseif (score >= 60)> D
    <#else> F
    </#if>
</#macro>

To merge this template with data, populate a Map with named attributes and pass this Map to the template.process() method. The following code creates a Configuration object that loads a FreeMarker template, template.ftl, from the classpath. An Enrollment object is added to the root Map, and the output of the template merge is written to a StringWriter:

import freemarker.template.Configuration;
import freemarker.cache.ClassTemplateLoader;
import freemarker.template.ObjectWrapper;
import freemarker.template.Template;

StringWriter writer = new StringWriter( );

// Create a Configuration object for FreeMarker
Configuration cfg = Configuration.getDefaultConfiguration( );
cfg.setTemplateLoader(new ClassTemplateLoader(getClass( )));
cfg.setObjectWrapper(ObjectWrapper.BEANS_WRAPPER);

// The root Map serves as a Context for our template engine
Map root = new HashMap( );
root.put("enrollment", testEnrollment( ));

// A template is processed with a Map and output is sent to a Writer.
Template template = cfg.getTemplate("template.ftl");
template.process(root, writer);
System.out.println("output: 
" + writer.toString( ));

The template is rendered, and the following output is printed to the console:

Stefan Winz,

Here is a summary of your performance in ECON 201 Macroeconomics.  

Class:         Macroeconomics
Professor:     Dr. Stephen H. Jones
Section:        002

Exam, Date, Score, Weight, Grade
-----------------------------------------------
T01, 01/10/03,    93.4, 1.00, A
T02, 01/27/03,    85.5, 1.50, B
Mid, 02/15/03,    98.0, 2.00, A+
T03, 03/31/03,    71.5, 1.00, C-
T04, 04/10/03,    88.5, 1.50, B+
Fin, 05/05/03,    95.0, 4.00, A

Final Grade:     91        A-

Your final grade has been submitted to the Registrar.  Have a great Summer!

In the template for this recipe, three objects are retrieved from an Enrollment object: a course property, a student property, and a List of Exam objects. Three variables—course, student, and exam—are created with the <#assign> directive, <#assign variable = expression >. Properties are referenced as they were referenced in JEXL and Velocity; ${enrollment.student} is used to access the student property on the enrollment. A student’s final course grade is calculated in a macro by calling <@final exams=exams/>. This macro assigns a global template variable, final, which is formatted to one decimal place with the expression ${final; m1M1}.

At first glance, a FreeMarker template looks very similar to a Velocity template, but there are several interesting features not available in Velocity:

Here are some other interesting FreeMarker features not available in Velocity:

It is beyond the scope of this book to drill into the details of every FreeMarker feature listed in this recipe. If you are interested in learning more about FreeMarker, take a look at the online documentation (http://www.freemarker.org/docs/index.html).

If you are using Jakarta Velocity and wish to migrate your templates to FreeMarker, the FreeMarker team has written a utility, code named “US Cavalry,” which will automatically translate your VTL templates to FTL templates. To obtain “US Cavalry,” see http://www.freemarker.org/usCavalry.html.