Introduction to Freemarker syntax

FTL is a template markup language for rendering data and for entering HTML structures. The syntax is as follows:

${book.name}

${book.name?if_exists}//value exists

${book.name??}//value exists

${book.name?has_content}//value exists

${book.name?default ("xxx")}//Default value XXX

${book.name! " XXX "}//Default value XXX

${book.date?string ("Yyyy-mm-dd")}//Date format

< #setting datetime_format= "Yyyy-mm-dd"/> ${post.pubtime?number_to_datetime}//date format, type long converted to YYYY-MM-DD format

${book?string.number}//number format, 20

${book?string.currency}//$20.00

${book?string.percent}//20%

< #assign foo=true>//declaring variables
${foo?string ("Yes", "No")}//yes

Use Lt,gt,lte,gte to replace comparison symbols

Built-in functions: use? To replace eg.${book?html}
String:
HTML---HTML Encoding of strings
Cap_first---String first letter Capitalization
Lower_case---Convert a string to lowercase
Trim---Remove whitespace characters before and after characters

sequences (sequence):
${list?size} size---Gets the number of elements in the sequence

Logical judgment

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

Quickly define a collection of int intervals
< #assign len = 0..100>//No need to use []

Looping through collections
< #list items as item> ${item} </#list >
Item_index: Index value of the current variable
Item_has_next: Whether the next object exists
< #if items?size! = 0></#if >: Judging the length of the set

Macros/Templates
Define macro:< #macro greet><p> Paragraph paragraph paragraphs <p></#macro >
Using the macro:< @greet ></@greet >
Define macro parameters: Follow the name of the macro
< #macro greet person color><p> Paragraph paragraph paragraphs <p></#macro >
When calling parameters, do not care about order issues:< @greet person= "John" color= "Red" ></@greet >
Use < #nested > nested macro Calls

Definition of hash and list
< #assign c={"a": "AAA", "B": "BBBB"}>
${C.A}//' AAA '

< #assign c=[1,2,3,4,5]>
< #list c[1..4] as v>
${V}
</#list >

Using compress to process output
< #compress >....</#compress > eliminate blank lines
< @compress single_line=true>...</@compress > compressed to one line

${} shows the,<> definition operator for the rendering of the variable? Function name

FTL instruction Rules:
1. Start tag < #if ...>
2. End tag </#if >
3. Empty Label < #assign x=2.582/>
The symbol at the front of the label is #, which refers to the system built-in instructions.
When the symbol at the front of the tag is @, it refers to the user instruction.

Reference: http://www.havenliu.com/goodarticle/420.html

Introduction to Freemarker syntax