Review FreeMarker

//1. Create a configuration instance
         Configuration cfg = new Configuration(Configuration.VERSION_2_3_23);
         cfg.setDirectoryForTemplateLoading(new File("templates")); //templates is the parallel of src
         cfg.setDefaultEncoding("UTF-8");
         cfg.setTemplateExceptionHandler(TemplateExceptionHandler.RETHROW_HANDLER);
//2. Get the template
         Template t1 = cfg.getTemplate("a.ftl");       
//3.Create a data-model
         Map<String, Object> rt = new HashMap<String, Object>();

         rt.put("user","Jetma");
         rt.put("random", Math.random()*100);
       
         List<String> list = new ArrayList<String>();
         list.add("sss");
         list.add("s02");
         rt.put("lst",list);
       
         rt.put("date1", new Date());
         rt.put("html1", "<h1>H1</h1>");

// 4
        Writer out = new OutputStreamWriter(System.out);
        t1.process(rt,out);
        out.flush();
        out.close();
-------------------------------
a.ftl:
${user}, welcome!<#-- comments -->
<#if user!="xx">you are a new one!</#if>
<#if random gte 60>${random} >= 60
<#else>${random} lt 60<#-- gt gte lt lte -->
</#if>
<#list lst as i1 >${i1},</#list>
//for include file
<#include "includedxx.txt" />
<@m1 /><@m1 /><#-- invode ml -->
<@m2 a="par1" b="par2" c="par3"/>
<@border>ne
  <@m2 a="nested1" b="nested2" c="r3"/>
</@border>
<#import "b.ftl" as bb/>
<@bb.copyright date="2016-03-01"/>
${bb.mail}
<#assign mail="my@google.com"/>
${mail}
<#assign mail="bb@bb.com" in bb/>
${bb.mail}

${date1?string("yyyy-MM-dd HH:mm:ss")}

<#assign html2="<b>Bold</b>"/>
${html2?html}
${html1?html}
${html1?cap_first}
${html1?lower_case}
${html1?upper_case}
-------------------
${sss!}<#-- if sss not define, default: "" -->
${sss! "abc"}<#-- if sss not define, default: "abc"-->
<#if user??><h1>${user}</h1></#if> <#-- Returns true if the user is not indicated, and false otherwise-->
<#if sss??><h1>sss ok</h1><#else> sss is not ok. </#if>
-----------------------------------------------------
 includedxx.txt:
included xx
<#macro m1><#-- define macro command -->
<b>macro m1 testing  1</b>
</#macro>
<#macro m2 a b c><#-- define macro command -->
<b>param:${a}--${b}--${c}</b>
</#macro>
nested command
<#macro border>
 <table border=1><tr><td>
 <#nested>
 </td></tr></table>
</#macro>
-----------------------------------------------------
b.ftl:
<#macro copyright date>
<p>Copyright (C) ${date} xxx.</p>
</#macro>
<#assign mail="xx@yahoo.com">
-----------------------------------------------------
Ref:
http://freemarker.incubator.apache.org/docs/pgui_quickstart_createconfiguration.html
http://freemarker.incubator.apache.org/docs/pgui_quickstart_createdatamodel.html

1. string and number

<#if str == "success">

    xxx

</#if>

<#if str !== "error">

    xxx

</#if>

2. List

<#if (list?size>0) >

</#if>

3. string 

<#if infos.name?length lt 7 >
${infos.name}
<#else>
${infos.name[0..6]}...
</#if>

4. if...else...

4. 1

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

4. 2

<#if x = 1>
  x is 1
</#if> 

4. 3 elseif

<#if x = 1>
  x is 1
<#elseif x = 2>
  x is 2
<#elseif x = 3>
  x is 3
</#if>  

4.4

<#if x = 1>
  x is 1
<#elseif x = 2>
  x is 2
<#elseif x = 3>
  x is 3
<#elseif x = 4>
  x is 4
<#else>
  x is not 1 nor 2 nor 3 nor 4
</#if> 

5 switch...case...default...

<#switch value>
  <#case refValue1>
    ...
    <#break>
  <#case refValue2>
    ...
    <#break>
  <#case refValueN>
    ...
    <#break>
  <#default>
    ...
</#switch>

5. 1
 <#switch being.size>

  <#case "small">
     This will be processed if it is small
     <#break>
  <#case "medium">
     This will be processed if it is medium
     <#break>
  <#case "large">
     This will be processed if it is large
     <#break>
  <#default>
     This will be processed if it is neither
</#switch>  

5. 2

<#switch x>
  <#case x = 1>
    1
  <#case x = 2>
    2
  <#default>
    d
</#switch>  

6.

<#list sequence as item>
    ...
</#list>

item_index，item_has_next，

<#assign seq = ["winter", "spring", "summer", "autumn"]>
<#list seq as x>
  ${x_index + 1}. ${x}<#if x_has_next>,</#if>
</#list>  

break