FreeMarker的if标签

if, else, elseif

Synopsis

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

Where:

• condition, condition2, ...etc.: Expression evaluates to a boolean value.

Description

You can use if, elseif andelse directives to conditionally skip a section of the template. Thecondition-s must evaluate to a boolean value, or else an error will abort template processing. Theelseif-s and else-s must occur insideif (that is, between the if start-tag and end-tag). The if can contain any number ofelseif-s (including 0) and at the end optionally oneelse. Examples:

if with 0 elseif and noelse:

	<#if x == 1> x is 1

if with 0 elseif andelse:

	<#if x == 1> x is 1 <#else> x is not 1

if with 2 elseif and noelse:

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

if with 3 elseif andelse:

	<#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

To see more about boolean expressions, see: Template Author's Guide/The Template/Expressions.

You can nest if directives (of course):

	<#if x == 1> x is 1 <#if y == 1> and y is 1 too <#else> but y is not <#else> x is not 1 <#if y < 0> and y is less than 0

Note

How to test if x is greater than 1? <#if x > 1> will bewrong, as FreeMarker will interpret the first > as the end of the tag. Thus, either write <#if (x > 1)> or<#if x > 1>.