有关freemarker的语法，循环，逻辑

==============常用语法=================
三．
EG.一个对象BOOK
1.输出 ${book.name}
空值判断：${book.name?if_exists },
${book.name?default(‘xxx’)}//默认值xxx
${ book.name!"xxx"}//默认值xxx
日期格式：${book.date?string('yyyy-MM-dd')}
数字格式：${book?string.number}--20
${book?string.currency}--<#-- $20.00 -->
${book?string.percent}—<#-- 20% -->
插入布尔值：
<#assign foo=ture />
${foo?string("yes","no")} <#-- yes -->



=============逻辑判断==================
2．
a:
<#if condition>...
<#elseif condit
inc 发布于2007-09-08 16:18:57
ion2>...
<#elseif condition3>......
<#else>...
其中空值判断可以写成<#if book.name?? >

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


===============循环读取=================
3．
<#list sequence as item>
...
</#list>
空值判断<#if bookList?size = 0></#list>
e.g.
<#list employees as e>
${e_index}. ${e.name}
</#list>

<#if mole?default(0)!=0>

=============用来压缩空白空间和空白的行===============

用例
<#assign x = "    moo    ">
(<#compress>
1 2 3   4    5
${moo}
test only

I said, test only

)
输出
(1 2 3 4 5
moo
test only
I said, test only)

==============Sequence内置的计数器==============

3. Sequence内置的计数器: xxx_index
用途：显示序号
模板:

<#list employees as e>
${e_index}. ${e.name}
</#list>

输出:

1. Readonly
2. Robbin


==============Sequence内置的分段器=====================
4. Sequence内置的分段器: chunk
用途：某些比较BT的排版需求
模板:

<#assign seq = ['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j']>
<#list seq?chunk(4) as row>
<ul>
<li><#list row as cell>${cell} </#list></li>
</ul>
</#list>

<#list seq?chunk(4, '-') as row>
<tr>
<td><#list row as cell>${cell} </#list></td>
</tr>
</#list>


输出:

<ul>
<li>a</li>
<li>b</li>
<li>c</li>
<li>d</li>
</ul>
<ul>
<li>e</li>
<li>f</li>
<li>g</li>
<li>h</li>
</ul>
<ul>
<li>i</li>
<li>j</li>
</ul>

<tr>
<td>a</td>
<td>b</td>
<td>c</td>
<td>d</td>
</tr>
<tr>
<td>e</td>
<td>f</td>
<td>g</td>
<td>h</td>
</tr>
<tr>
<td>i</td>
<td>j</td>
<td>-</td>
<td>-</td>
</tr>




=====================freemarker的list================================


Scalar String:${scalarString}   
Scalar Number:${scalarNumber}
Object is:${scalarObject}

List使用样例-List元素为Scalar对象:

<#list scalarList as value0>
    Scalar List值：${value0}
</#list>

List使用样例-List元素为User对象:

<#list userList as listUser>
    List对象User Id值：${listUser.userId}
</#list>

Map使用样例-Map Values元素为Scalar :

<#list scalarMap?keys as mykey>
    Scalar Map key is :${mykey}
    Scalar Map value is:${scalarMap[mykey]}
</#list>

Map使用样例-Map Values元素为User对象:

<#list userMap?keys as key1>
    <#assign mapUser="${userMap[key1]}" >
    User Object is :${mapUser}
    <#--
    以下方法有问题
    User is :${mapUser.userId} <br>
    -->
</#list>

==============FreeMarker中list排序==============
升序：
<#list list?sort_by("time") as v>
</#list>
降序：
<#list list?sort_by("time") as v>
</#list>




===============freemarker在模板中定义变量==============

在模板中定义的变量有三种类型：
plain变量：可以在模板的任何地方访问，包括include指令插入的模板，使用assign指令创建和替换
<#include "/WEB-INF/index/top.html">


==============freemarker.properties配置================
（1）解决输出中文乱码问题：
default_encoding=UTF-8
locale=zh_CN
number_format=#

（2）提高freemarker的性能
template_update_delay=60000

（3）freemarker的标签种类：
${..}
# 代表是FTL tags
<#if ...></#if>
<#list totalList as elementObject>...</#list>
@ ,代表用户自定义的标签
<#-- --> 注释标签，注意不是<!-- -->

=====================将图片整除换行====== <#if (u_index+1)%4=0>当图片超过五个就换行=======
   <table width="100%">
                      <tr>
                        <td><table width="100%">
                          <tr>
              <#if map["最新-图片"]?exists>
     <#list map["最新-图片"] as u>
     <#if (u_index+1)%4=0>
                <td><table width="70" height="65" border="0" cellpadding="0" cellspacing="0">
                  <tr>

                    <td align="center" valign="middle" bgcolor="#6F7074">
                    <a target="_blank" href="shownews.page?id=${u.id?default("")}&mole=2 "><img src="${u.chartpath?default('')}" width="67" height="41" border="0" /></a></td>
                  </tr>
                  <tr>
                    <td align="center" bgcolor="#6F7074">
                    <a target="_blank" href="shownews.page?id=${u.id?default("")}&mole=2 " class="tableff">
                    <@jf.greet title=u.title len=4 /></a>
                    </td>
                  </tr>

                </table></td></tr><tr >
     <#else>
     <td><table width="70" height="65" border="0" cellpadding="0" cellspacing="0">
                  <tr>

                    <td align="center" valign="middle" bgcolor="#6F7074">
                    <a target="_blank" href="shownews.page?id=${u.id?default("")}&mole=2 "><img src="${u.chartpath?default('')}" width="67" height="41" border="0" /></a></td>
                  </tr>
                  <tr>
                    <td align="center" bgcolor="#6F7074">
                    <a target="_blank" href="shownews.page?id=${u.id?default("")}&mole=2 " class="tableff">
                    <@jf.greet title=u.title len=4 /></a>
                    </td>
                  </tr>

                </table></td>
     </#if>
     </#list>
     </#if>
              </tr>            
            </table>
                    </td>
                  </tr>
                </table>
                  </tr>
                </table></td>
     </#if>
     </#list>
     </#if>
              </tr>            
            </table>
                    </td>
                  </tr>
                </table>

===============================freemarker中在application
${Application.web_title}

在类里：
list=dser.indexvideo(cvo);
if(list.size()!=0){
map.put("最新",list);}

在html静态页里：
<#import "/WEB-INF/ftl/index.ftl" as jf>
（index.ftl
<#macro greet title len>
<#if title?length != 0>
<#if (title?length>len)>
${title[0..len-1]} <#else>
${title?trim}
</#if>
<#else>
${title?default("")}
</#if>
</#macro>
<#--时间比较-->
<#macro vstime start end>
<#if start?default("")==""||end?default("")=="">
--
<#else>
<#assign starts=start?replace("-","") >
<#assign ends=end?replace("-","") >
<#if (starts?number>ends?number)>
<font color="red">以过期</font>
<#else>
未过期
</#if>
</#if>
</#macro>
）

<#if map["最新"]?exists>
<#list map["最新"] as u>
${u.filepath?default('')}
<@jf.greet title=u.title len=6 />
</#list></#if>