freemarker自定义标签（与java合用）

自定义类继承FreemarkerManager类，重写protected Configuration createConfiguration(ServletContext servletContext)throws TemplateException方法定义有哪些TemplateDirectiveModel类与它的别名[自定义标签名称]，通过Spring来取：

import java.util.Map;

import javax.servlet.ServletContext;

import org.apache.struts2.views.freemarker.FreemarkerManager;

import org.springframework.context.ApplicationContext;

import org.springframework.web.context.support.WebApplicationContextUtils;

import freemarker.template.Configuration;

import freemarker.template.TemplateDirectiveModel;

import freemarker.template.TemplateException;

/**

 * 从spring取得所有的TemplateDirectiveModel类的对象，全部取出来，交给struts管理

 * @author Administrator


 *
 */

public class DirectiveFreemarkerManager extends FreemarkerManager{

    @Override

    protected Configuration createConfiguration(ServletContext servletContext)

            throws TemplateException {

        //调用你父类操作

        Configuration  configuration=super.createConfiguration(servletContext);

        //设定在页面使用的标签的类型 (([]、<>),[]这种标记解析要快些)      [] SQUARE_BRACKET_TAG_SYNTAX  ,  <>ANGLE_BRACKET_TAG_SYNTAX

        configuration.setTagSyntax(Configuration.AUTO_DETECT_TAG_SYNTAX);

        //取得spring所管理所有的对象 ClassPathXmlApplication,  WebAplicationContext

        ApplicationContext  appContext=WebApplicationContextUtils.getRequiredWebApplicationContext(servletContext);

        // 获取实现TemplateDirectiveModel的bean

        Map<String, TemplateDirectiveModel>  beans= appContext.getBeansOfType(TemplateDirectiveModel.class);

        //再把这些类，全部交给struts的freemarker来管理

        //Component("upper") public class UpperDirective implements TemplateDirectiveModel

        for(String key : beans.keySet()){

            Object obj=beans.get(key);  //TemplateDirectiveModel

            if(obj!=null && obj instanceof  TemplateDirectiveModel){

                configuration.setSharedVariable(key, obj);

            } 

        }

        return configuration;

    }
}

在struts.xml中添加：

 <!-- 让struts来管理freemarker自定义标签类 struts.freemarker.manager.classname=org.apache.struts2.views.freemarker.FreemarkerManager -->
    <constant name="struts.freemarker.manager.classname" value="com.xxxx.struts.DirectiveFreemarkerManager"></constant>

编写TemplateDirectiveModel，并交给Spring管理：

import java.io.IOException;

import java.io.Writer;

import java.util.Map;

import org.springframework.stereotype.Component;

import freemarker.core.Environment;

import freemarker.template.TemplateDirectiveBody;

import freemarker.template.TemplateDirectiveModel;

import freemarker.template.TemplateException;

import freemarker.template.TemplateModel;

import freemarker.template.TemplateModelException;


/**
自定义指定，作用，把嵌套的内容中的小写全部转换为大写字母



@author Administrator






/


@Component("upper")


public class UpperDirective implements TemplateDirectiveModel {


//evn  环境输出


//params 参数


//loopVars 循环


//body   内容


    @Override


public void execute(Environment env, Map params,


TemplateModel[] loopVars, TemplateDirectiveBody body)


throws TemplateException, IOException {


//如果有参数 应该不支持参数


if(!params.isEmpty()){


throw new TemplateModelException(


"这个指令不允许使用参数.");


}


if(loopVars.length!=0){


throw new TemplateModelException(


"这个指令不允许使用循环参数.");


}


// 如果嵌套内容不为空的


if(body!=null){


//如果有内容，自己去重写输出流


body.render( new UpperCaseFilterWriter(env.getOut()));

 }</span><span style="color: #0000ff">else</span><span style="color: #000000">{</br>
     </span><span style="color: #0000ff">throw</span> <span style="color: #0000ff">new</span> RuntimeException("无内容异常"<span style="color: #000000">);</br>
 }</br>

}


//内部类


private static class UpperCaseFilterWriter extends Writer{


private final Writer out;  //接收网页中的输出 流对象


public UpperCaseFilterWriter(Writer out){


this.out=out;


}


//cbuf 文字内容， off位移，len 文字长度


        @Override


public void write(char[] cbuf, int off, int len) throws IOException {


char[] transformedChar=new char[len];


for(int i=0;i<len;i++){


transformedChar[i]=Character.toUpperCase(cbuf[i+off]);


}


out.write(transformedChar); 


}


@Override

public void flush() throws IOException {


out.flush();


}


@Override


public void close() throws IOException {


out.close();


} 


}


}

编写action,result—>字符串，type=”freemarker”：

<!-- 约定大于配置   /admin/Flinktype_list.action  --> 

   <package name="freemarkerPackage" namespace="/admin" extends="commonPackage" >

       <action name="*_*" class="{1}Action" method="{2}">

           <result name="{2}" type="freemarker">/admin/template/{1}/{2}.ftl</result> 

       </action>

   </package>

模板/template/upper.ftl：

<!DOCTYPE html>

<html lang="ch-ZN">

<head>

<meta charset="utf-8">

<meta http-equiv="X-UA-Compatible" content="IE=edge">

<meta name="viewport" content="width=device-width, initial-scale=1">

<meta name="description" content="">

<meta name="author" content="">

<title>freemarker自定义标签</title>
</head>

<body>  

<span style="color: #0000ff">&lt;</span><span style="color: #800000">@upper</span><span style="color: #0000ff">&gt;</span><span style="color: #000000"></br>
      bar
      </span><span style="color: #0000ff">&lt;</span><span style="color: #800000">#-- </span><span style="color: #ff0000">All kind of FTL is allowed here --</span><span style="color: #0000ff">&gt;</span></br>
      <span style="color: #0000ff">&lt;</span><span style="color: #800000">#list </span><span style="color: #ff0000">["red", "green", "blue"] as color</span><span style="color: #0000ff">&gt;</span><span style="color: #000000"></br>
        ${color}</br>
      </span><span style="color: #0000ff">&lt;/</span><span style="color: #800000">#list</span><span style="color: #0000ff">&gt;</span><span style="color: #000000"></br>
      baaz</br>
 </span><span style="color: #0000ff">&lt;/</span><span style="color: #800000">@upper</span><span style="color: #0000ff">&gt;</span></br></br></br>

<span style="color: #0000ff">&lt;</span><span style="color: #800000">hr</span><span style="color: #0000ff">/&gt;</span></br></br>

<span style="color: #0000ff">&lt;</span><span style="color: #800000">@cms_linktype    </span><span style="color: #ff0000">limit</span><span style="color: #0000ff">="0,10"</span> <span style="color: #0000ff">&gt;</span><span style="color: #000000"></br>
     请选择分类: </span><span style="color: #0000ff">&lt;</span><span style="color: #800000">select</span><span style="color: #0000ff">&gt;</span></br>
           <span style="color: #0000ff">&lt;</span><span style="color: #800000">#list  </span><span style="color: #ff0000">arrTypes as x</span><span style="color: #0000ff">&gt;</span></br>
              <span style="color: #0000ff">&lt;</span><span style="color: #800000">option </span><span style="color: #ff0000">value</span><span style="color: #0000ff">="${x.id}"</span><span style="color: #0000ff">&gt;</span>${x.typeName}<span style="color: #0000ff">&lt;/</span><span style="color: #800000">option</span><span style="color: #0000ff">&gt;</span></br>
           <span style="color: #0000ff">&lt;/</span><span style="color: #800000">#list</span><span style="color: #0000ff">&gt;</span> </br>
     <span style="color: #0000ff">&lt;/</span><span style="color: #800000">select</span><span style="color: #0000ff">&gt;</span></br>
<span style="color: #0000ff">&lt;/</span><span style="color: #800000">@cms_linktype</span><span style="color: #0000ff">&gt;</span></br>

</body>