FreeMarker概述
- FreeMarker是一個模板引擎，一個基于模板生成文本輸出的通用工具，使用純Java編寫
- Template + data model = output
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Hello world
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import java.io.StringWriter;import java.util.HashMap;import java.util.Locale;
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import freemarker.template.Configuration;import freemarker.template.Template;
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publicclass FreeMarkerTest {
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publicstaticvoid main(String[] args){
FreeMarkerTest test = new FreeMarkerTest();
test.sayHello("Hermit");
}
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publicvoid sayHello(String name){
Configuration freemarkerCfg = new Configuration();
freemarkerCfg.setClassForTemplateLoading(this.getClass(), "/");
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freemarkerCfg.setEncoding(Locale.getDefault(), "UTF-8");
Template template;
Locale.setDefault(Locale.ENGLISH);
try{
template = freemarkerCfg.getTemplate("Hello.ftl");
template.setEncoding("UTF-8");
HashMap root = newHashMap();
root.put("user", name);
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StringWriter writer = newStringWriter();
template.process(root, writer);
System.out.println(writer.toString());
}catch(Exception e){
e.printStackTrace();
}}
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}
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Hello ${user}!
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Hello Hermit!
空值的處理
在我們的程序中難免會碰到值為空的時候，如果用一個空值直接去替換模板中的標記，freemarker會毫不猶豫的拋出異常，并把錯誤信息直接寫到輸出結果里。為了對付這種情況我們有兩種寫法
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Hello ${user!}!
Hello ${user?if_exists}
Hello ${user!'your name'}!
Hello ${user?default('your name')}
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test.sayHello(null);
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Hello?!
Hello your name!
Hello
Hello your name
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freemarker國際化模板
freemarker支持多語言國際化，只要把模板名稱按照java資源文件的寫法就可以了,也就是name_語言_國家地區.ftl 如果找不到對應的語言，就會用默認語言的模板。
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import java.io.StringWriter;import java.util.HashMap;import java.util.Locale;
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import freemarker.template.Configuration;import freemarker.template.Template;
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publicclass FreeMarkerTest {
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publicstaticvoid main(String[] args){
FreeMarkerTest test = new FreeMarkerTest();
test.sayHello("hermit",Locale.CHINA);
test.sayHello("hermit",Locale.ENGLISH);
}
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publicvoid sayHello(String name,Locale locale){
Configuration freemarkerCfg = new Configuration();
freemarkerCfg.setClassForTemplateLoading(this.getClass(), "/");
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freemarkerCfg.setEncoding(Locale.getDefault(), "UTF-8");
Template template;
Locale.setDefault(Locale.ENGLISH);
try{
template = freemarkerCfg.getTemplate("Hello.ftl",locale);
template.setEncoding("UTF-8");
HashMap root = newHashMap();
root.put("user", name);
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StringWriter writer = newStringWriter();
template.process(root, writer);
System.out.println(writer.toString());
}catch(Exception e){
e.printStackTrace();
}}
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}
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Hello ${user!}!
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你好 ${user!}!
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你好 hermit!
Hello hermit!
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在struts項目中使用freemarker
- 1、引入freemarker.jar
- 2、web.xml加入
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<!-- FreeMarker view servlet (to replace JSP) --><servlet><servlet-name>freemarker</servlet-name><servlet-class>
freemarker.ext.servlet.FreemarkerServlet
</servlet-class>
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<!-- FreemarkerServlet settings: --><init-param><param-name>TemplatePath</param-name><param-value>/</param-value></init-param><init-param><param-name>NoCache</param-name><param-value>true</param-value></init-param><init-param><param-name>ContentType</param-name><param-value>text/html</param-value></init-param>
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<!-- FreeMarker settings: --><init-param><param-name>template_update_delay</param-name><param-value>0</param-value><!-- 0 is for development only! Use higher value otherwise. --></init-param><init-param><param-name>default_encoding</param-name><param-value>utf-8</param-value></init-param><init-param><param-name>locale</param-name><param-value>en_US</param-value></init-param><init-param><param-name>number_format</param-name><param-value>0.##########</param-value></init-param>
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<load-on-startup>1</load-on-startup></servlet>
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<servlet-mapping><servlet-name>freemarker</servlet-name><url-pattern>*.ftl</url-pattern></servlet-mapping>
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- 3、一個示例頁面
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<html><head><title>Say Hello</title><METAHTTP-EQUIV="Content-Type"CONTENT="text/html; charset=utf-8"></head><body><h1>Hello ${user}!</h1></body></html>
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我們完全可以用freemarker的模板取代JSP頁面。用freemarker的模板看起更簡潔，可讀性更強。比如現在struts2的UI標簽就是用freemarker做的。
freemarker用struts標簽做國際化
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<#assign html =JspTaglibs["/WEB-INF/struts-html.tld"]><#assign bean =JspTaglibs["/WEB-INF/struts-bean.tld"]><#assign logic =JspTaglibs["/WEB-INF/struts-logic.tld"]><html><head><title> FreeMarker Struts Example </title><metahttp-equiv ="Content-type"content ="text/html; charset=utf-8"></ head ><body><@bean.message key ="hello" arg0 ="hermit"/></body></html>
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主要是引入標簽的時候要這樣寫：
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<#assign html =JspTaglibs["/WEB-INF/struts-html.tld"]>
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freemarker直接使用資源文件進行多語言國際化
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import java.io.StringWriter;import java.util.HashMap;import java.util.Locale;import java.util.ResourceBundle;
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import freemarker.ext.beans.BeansWrapper;import freemarker.ext.beans.ResourceBundleModel;import freemarker.template.Configuration;import freemarker.template.Template;
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publicclass FreeMarkerTest {
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publicstaticvoid main(String[] args){
FreeMarkerTest test = new FreeMarkerTest();
test.sayHello("hermit",Locale.CHINA);
test.sayHello("hermit",Locale.ENGLISH);
}
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publicvoid sayHello(String name,Locale locale){
Configuration freemarkerCfg = new Configuration();
freemarkerCfg.setClassForTemplateLoading(this.getClass(), "/");
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freemarkerCfg.setEncoding(Locale.getDefault(), "UTF-8");
Template template;
Locale.setDefault(Locale.ENGLISH);
try{
template = freemarkerCfg.getTemplate("Hello.ftl");
template.setEncoding("UTF-8");
HashMap root = newHashMap();
root.put("user", name);
ResourceBundle RESOURCE_BUNDLE = ResourceBundle.getBundle("ApplicationResources",locale);
ResourceBundleModel rsbm = new ResourceBundleModel(RESOURCE_BUNDLE,new BeansWrapper());
root.put("bundle", rsbm);
StringWriter writer = newStringWriter();
template.process(root, writer);
System.out.println(writer.toString());
}catch(Exception e){
e.printStackTrace();
}}
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}
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${bundle("hello","hermit")}
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hello=Hello {0}\!
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hello=你好 {0}\!
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你好 hermit!
Hello hermit!
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關鍵的地方就是用ResourceBundleModel把ResourceBundle轉換一下。
常用的2種加載模板的方式
- 普通java類根據當前class上下文環境加載模板
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cfg.setClassForTemplateLoading(this.getClass(), "/");
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- 在web項目中根據servlet上下文環境加載模板
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cfg.setServletContextForTemplateLoading(this.getServlet().getServletContext(), "/");
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posted on 2007-05-29 17:03
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