Java模板引擎之FreeMarker超入门
FreeMarker 是一个采用 Java 开发的模版引擎,是一个基于模版生成文本的通用工具。 它被设计用来生成 HTML Web 页面,特别是基于 MVC 模式的应用程序。虽然使用FreeMarker需要具有一些编程的能力,但通常由 Java 程序准备要显示的数据,由 FreeMarker 生成页面,并通过模板显示准备的数据。
http://freemarker.org/
版本:2.3.19
Java代码
public void process(String template, Map<String, ?> data) throws Exception { Configuration cfg = new Configuration(); cfg.setDirectoryForTemplateLoading(new File("ftl")); cfg.setObjectWrapper(new DefaultObjectWrapper()); //设置字符集 cfg.setDefaultEncoding("UTF-8"); //设置尖括号语法和方括号语法,默认是自动检测语法 // 自动 AUTO_DETECT_TAG_SYNTAX // 尖括号 ANGLE_BRACKET_TAG_SYNTAX // 方括号 SQUARE_BRACKET_TAG_SYNTAX cfg.setTagSyntax(Configuration.AUTO_DETECT_TAG_SYNTAX); Writer out = new OutputStreamWriter(new FileOutputStream(FILE_DIR + template + ".txt"),"UTF-8"); Template temp = cfg.getTemplate(template); temp.process(data, out); out.flush(); }
1、计算式
引用
<#-- 1、算术运算 -->[BR]
${3 + 4}
<#-- 2、内建函数 -->[BR]
${"rensanning"?upper_case}
2、输出一个值
Java代码
HashMap t2root = new HashMap<String, String>(); t2root.put("user", "RenSanNing");
引用
${user}, Welcome!
3、输出一个列表
Java代码
Map<String, Object> t3root = new HashMap<String, Object>(); List<Food> menu = new ArrayList<Food>(); menu.add(new Food("iText in Action", 98)); menu.add(new Food("iBATIS in Action", 118)); menu.add(new Food("Lucene in Action", 69)); t3root.put("menu", menu);
引用
<#list menu as food>
${food.name} ${food.price?string.currency}
</#list>
4、逻辑判断(IF,SWITCH)
Java代码
Map<String, Object> t4root = new HashMap<String, Object>(); t4root.put("x", 2); t4root.put("y", "medium");
引用
<1>if, else, elseif:
<#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>
<2>switch, case, default, break:
<#switch y>
<#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>
<3>list, break:
<#assign seq = ["winter", "spring", "summer", "autumn"]>
<#list seq as x>
${x_index + 1}. ${x}<#if x_has_next>,</#if>
</#list>
5、自定义函数
引用
<#function fact n>
<#if n == 0>
<#return 1 />
<#else>
<#return fact(n - 1) * n />
</#if>
</#function>
<#list 0..10 as i>
${i}! => ${fact(i)}
</#list>
6、定义变量
引用
<#-- 1、本地变量 -->[BR]
<#function partg n lst>
<#local ans = []>
<#list lst as x>
<#if (x >= n)>
<#local ans = ans + [x]>
</#if>
</#list>
<#return ans>
</#function>
<#assign ls = [10, 2, 4, 5, 8, 1, 3]>
<#list partg(4, ls) as x>${x} </#list>
<#-- 2、变量域测试 -->[BR]
<#macro test>
03. ${x}
<#global x = "global2">
04. ${x}
<#assign x = "assign2">
05. ${x}
<#local x = "local1">
06. ${x}
<#list ["循环1"] as x>
07. ${x}
<#local x = "local2">
08. ${x}
<#assign x = "assign3">
09. ${x}
</#list>
10. ${x}
</#macro>
<#global x = "global1" />
01. ${x}
<#assign x = "assign1" />
02. ${x}
<@test />
11. ${x}
7、定义宏macro
引用
<#-- 1、无参数 -->[BR]
<#macro greet>
Welcome!
</#macro>
<@greet />
<#-- 2、有参数 -->[BR]
<#macro greet user>
${user}, Welcome!
</#macro>
<@greet user="RenSanNing"/>
<#-- 3、有多个参数 -->[BR]
<#macro table cols rows>
<table>
<#list 1..rows as row>
<tr>
<#list 1..cols as col>
<td>${row}, ${col}</td>
</#list>
</tr>
</#list>
</table>
</#macro>
<@table cols=3 rows=2 />
<#-- 4、中间跳出 -->[BR]
<#macro out>
显示文字
<#return>
不显示文字
</#macro>
<@out />
<#-- 5、嵌套 -->[BR]
<#macro lprint lst>
<#list lst as item>
・${item}<#nested item />
</#list>
</#macro>
<@lprint 1..3; x>^2 = ${x * x}</@lprint>
<@lprint 1..3; x>^3 = ${x * x * x}</@lprint>
<@lprint ["Let's go", "to the", "land of Medetai"] />
8、include
引用
<#include "T108include.ftl">
${url}
<@greet name="rensanning" />
T108include.ftl
引用
<#macro greet name>
${name}, Welcome!
</#macro>
<#assign url="http://www.baidu.com/">
9、名字空间
引用
<#import "T109include.ftl" as my>
<#assign url="http://www.google.com/">
${my.url}
<@my.greet name="rensanning" />
${url}
T109include.ftl
引用
<#macro greet name>
${name}, Welcome!
</#macro>
<#assign url="http://www.baidu.com/">
10、自定义指令Directive
Java代码
public class SystemDateDirective implements TemplateDirectiveModel { public void execute(Environment env, Map params, TemplateModel[] loopVars, TemplateDirectiveBody body) throws TemplateException, IOException { Calendar cal = Calendar.getInstance(); SimpleDateFormat sdf = new SimpleDateFormat("yyyy/MM/dd HH:mm:ss"); env.getOut().append(sdf.format(cal.getTime())); } }
Java代码
public class TextCutDirective implements TemplateDirectiveModel { public static final String PARAM_S = "s"; public static final String PARAM_LEN = "len"; public static final String PARAM_APPEND = "append"; @SuppressWarnings("unchecked") public void execute(Environment env, Map params, TemplateModel[] loopVars, TemplateDirectiveBody body) throws TemplateException, IOException { String s = getString(PARAM_S, params); Integer len = getInt(PARAM_LEN, params); String append = getString(PARAM_APPEND, params); if (s != null) { Writer out = env.getOut(); if (len != null) { out.append(textCut(s, len, append)); } else { out.append(s); } } } ....
Java代码
Map<String, Object> t10root = new HashMap<String, Object>(); t10root.put("systemdate", new SystemDateDirective()); t10root.put("text_cut", new TextCutDirective());
引用
<@systemdate/>
<@text_cut s="汉字汉字汉字汉字汉字汉字汉字汉字汉字汉字" len=10 append="..."/>
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