What is FreeMarker?

Language/Java 2007. 7. 27. 18:19 by 정민군

과거에는 velocity가 주로 템플릿 엔진으로 사용이 됐는데, 최근에는 webwork와 함께 FreeMarker가 주목을 많이 받고 있는듯 하다.

What is FreeMarker?

FreeMarker is a "template engine"; a generic tool to generate text output (anything from HTML to autogenerated source code) based on templates. It's a Java package, a class library for Java programmers. It's not an application for end-users in itself, but something that programmers can embed into their products.

Template + data model = output

Ubiquitous Language : 용어정리를 해보자
- We say that the output is created by merging a template and a data model
- Files like this are called templates.

Templates

<html>
<head>
  <title>Welcome!</title>
</head>
<body>
  <h1>
    Welcome ${user}<#if user = "Big Joe">, our beloved leader</#if>!
  </h1>
  <p>Our latest product:
  <a href="${latestProduct.url}">${latestProduct.name}</a>!
</body>
</html>

Data Model : the data model is basically a tree

(root)
  |
  +- user = "Big Joe"
  |
  +- latestProduct
      |
      +- url = "products/greenmouse.html"
      |
      +- name = "green mouse"

Directive

* 조건문만 알면 어떤 랭귀지라도 대강 코딩할 수 있죠? 다음과 같은 syntax입니다.
Synopsis

<#if condition>
...
<#elseif condition2>
...
<#elseif condition3>
...
...
<#else>
...
</#if>

* 기대하고 기대하는 loop사용하는 방법
<#list SequenceVar as variable>repeatThis</#list>

<p>And BTW we have these fruits:
<ul>

<#list whatnot.fruits as fruit>
 <li>${fruit}
</#list>
<ul>

* include

<html>
<head>
  <title>Test page</title>
</head>
<body>
  <h1>Test page</h1>
  <p>Blah blah...
<#include "/copyright_footer.html">
</body>
</html>

* Using directives together : 함께 사용할 수도 있슴

<p>We have these animals:
<table border=1>
  <tr><th>Name<th>Price
  <#list animals as being>
  <tr>
    <td>
      <#if being.size = "large"><b></#if>
      ${being.name}
      <#if being.size = "large"></b></#if>
    <td>${being.price} Euros
  </#list>
</table>

ouput을 만들기 위한 샘플코드

public String createTemplateContents(String fileName, Object root) throws Exception {
final Writer out = new StringWriter();
Configuration cfg = new Configuration();
cfg.setClassicCompatible(false);
cfg.setClassForTemplateLoading(getClass(), THEME_TEMPLATES_CLASSPATH);
cfg.setObjectWrapper(new DefaultObjectWrapper());
Template temp = cfg.getTemplate(fileName);
temp.process(root, out);
out.flush();
return out.toString();
}