freemarker中实现自定义标签

 import    java.io.IOException;
   import    java.io.Writer;
   import    java.util.Iterator;
   import    java.util.Map;

   import    freemarker .core.Environment;
 import    freemarker .template.SimpleNumber;
 import    freemarker .template.TemplateBooleanModel;
 import    freemarker .template.TemplateDirectiveBody;
 import    freemarker .template.TemplateDirectiveModel ;
 import    freemarker .template.TemplateException;
 import    freemarker .template.TemplateModel;
 import    freemarker .template.TemplateModelException;
 import    freemarker .template.TemplateNumberModel;

 /**
  * FreeMarker  自定义标签实现重复输出内容体。
  *
  *
  * 参数:
  * count: 重复的次数，必须的且非负整数。
  * hr: 设置是否输出HTML标签 "hr" 元素. Boolean. 可选的默认为fals.
  *
  *
  * 循环变量: 只有一个，可选的. 从1开始。
  *
  *
  */
 public     class    RepeatDirective  implements    TemplateDirectiveModel  {

      private     static     final    String PARAM_NAME_COUNT =  "count"  ;
      private     static     final    String PARAM_NAME_HR =  "hr"  ;

      public     void    execute(Environment env, Map params, TemplateModel[] loopVars,
             TemplateDirectiveBody body)  throws    TemplateException, IOException {

          // ---------------------------------------------------------------------
          // 处理参数

          int    countParam =  0  ;
          boolean    countParamSet =  false   ;
          boolean    hrParam =  false   ;

         Iterator paramIter = params.entrySet().iterator();
          while    (paramIter.hasNext()) {
             Map.Entry ent = (Map.Entry) paramIter.next();

             String paramName = (String) ent.getKey();
             TemplateModel paramValue = (TemplateModel) ent.getValue();

              if    (paramName.equals(PARAM_NAME_COUNT)) {
                  if    (!(paramValue  instanceof    TemplateNumberModel)) {
                      throw     new    TemplateModelException( "The \""   + PARAM_NAME_HR
                             +  "\" parameter "   +  "must be a number."  );
                 }
                 countParam = ((TemplateNumberModel) paramValue).getAsNumber()
                         .intValue();
                 countParamSet =  true   ;
                  if    (countParam <  0  ) {
                      throw     new    TemplateModelException( "The \""   + PARAM_NAME_HR
                             +  "\" parameter "   +  "can't be negative."  );
                 }
             }  else     if    (paramName.equals(PARAM_NAME_HR)) {
                  if    (!(paramValue  instanceof    TemplateBooleanModel)) {
                      throw     new    TemplateModelException( "The \""   + PARAM_NAME_HR
                             +  "\" parameter "   +  "must be a boolean."  );
                 }
                 hrParam = ((TemplateBooleanModel) paramValue).getAsBoolean();
             }  else    {
                  throw     new    TemplateModelException( "Unsupported parameter: "
                         + paramName);
             }
         }
          if    (!countParamSet) {
              throw     new    TemplateModelException( "The required \""
                     + PARAM_NAME_COUNT +  "\" paramter"   +  "is missing."  );
         }

          if    (loopVars.length >  1  ) {
              throw     new    TemplateModelException(
                      "At most one loop variable is allowed."  );
         }

          // Yeah, it was long and boring...

          // ---------------------------------------------------------------------
          // 真正开始处理输出内容

         Writer out = env.getOut();
          if    (body !=  null   ) {
              for    ( int    i =  0  ; i < countParam; i++) {
                  // 输出  <hr> 如果 参数hr 设置为true
                  if    (hrParam && i !=  0  ) {
                     out.write( "<hr>"  );
                 }

                  // 设置循环变量
                  if    (loopVars.length >  0  ) {
                     loopVars[ 0  ] =  new    SimpleNumber(i +  1  );
                 }

                  // 执行标签内容(same as <#nested> in FTL).
                 body.render(env.getOut());
             }
         }
     }

 }

import java.io.IOException;
import java.io.Writer;
import java.util.Iterator;
import java.util.Map;
 
import freemarker
.core.Environment;
import freemarker
.template.SimpleNumber;
import freemarker
.template.TemplateBooleanModel;
import freemarker
.template.TemplateDirectiveBody;
import freemarker
.template.TemplateDirectiveModel
;
import freemarker
.template.TemplateException;
import freemarker
.template.TemplateModel;
import freemarker
.template.TemplateModelException;
import freemarker
.template.TemplateNumberModel;
/**
 * FreeMarker
 自定义标签实现重复输出内容体。
 * 
 * 
 * 参数:
 * count: 重复的次数，必须的且非负整数。
 * hr: 设置是否输出HTML标签 "hr" 元素. Boolean. 可选的默认为fals.
 * 
 * 
 * 循环变量: 只有一个，可选的. 从1开始。
 * 
 * 
 */
public class RepeatDirective implements TemplateDirectiveModel
 {
private static final String PARAM_NAME_COUNT = "count";
private static final String PARAM_NAME_HR = "hr";
public void execute(Environment env, Map params, TemplateModel[] loopVars,
TemplateDirectiveBody body) throws TemplateException, IOException {
// ---------------------------------------------------------------------
// 处理参数
int countParam = 0;
boolean countParamSet = false;
boolean hrParam = false;
Iterator paramIter = params.entrySet().iterator();
while (paramIter.hasNext()) {
Map.Entry ent = (Map.Entry) paramIter.next();
String paramName = (String) ent.getKey();
TemplateModel paramValue = (TemplateModel) ent.getValue();
if (paramName.equals(PARAM_NAME_COUNT)) {
if (!(paramValue instanceof TemplateNumberModel)) {
throw new TemplateModelException("The \"" + PARAM_NAME_HR
+ "\" parameter " + "must be a number.");
}
countParam = ((TemplateNumberModel) paramValue).getAsNumber()
.intValue();
countParamSet = true;
if (countParam < 0) {
throw new TemplateModelException("The \"" + PARAM_NAME_HR
+ "\" parameter " + "can't be negative.");
}
} else if (paramName.equals(PARAM_NAME_HR)) {
if (!(paramValue instanceof TemplateBooleanModel)) {
throw new TemplateModelException("The \"" + PARAM_NAME_HR
+ "\" parameter " + "must be a boolean.");
}
hrParam = ((TemplateBooleanModel) paramValue).getAsBoolean();
} else {
throw new TemplateModelException("Unsupported parameter: "
+ paramName);
}
}
if (!countParamSet) {
throw new TemplateModelException("The required \""
+ PARAM_NAME_COUNT + "\" paramter" + "is missing.");
}
if (loopVars.length > 1) {
throw new TemplateModelException(
"At most one loop variable is allowed.");
}
// Yeah, it was long and boring...
// ---------------------------------------------------------------------
// 真正开始处理输出内容
Writer out = env.getOut();
if (body != null) {
for (int i = 0; i < countParam; i++) {
// 输出  <hr> 如果 参数hr 设置为true
if (hrParam && i != 0) {
out.write("<hr>");
}
// 设置循环变量
if (loopVars.length > 0) {
loopVars[0] = new SimpleNumber(i + 1);
}
// 执行标签内容(same as <#nested> in FTL). 
body.render(env.getOut());
}
}
}
}

 

 import    java.io.File;
 import    java.io.IOException;
 import    java.io.Writer;
 import    java.util.Map;

 import    freemarker .template.Configuration;
 import    freemarker .template.DefaultObjectWrapper;
 import    freemarker .template.Template;
 import    freemarker .template.TemplateException;

 /**
  *
  * 模板工具类
  */
 public     class    FreeMarkertUtil {
      /**
      * @param templatePath 模板文件存放目录
      * @param templateName 模板文件名称
      * @param root 数据模型根对象
      * @param templateEncoding 模板文件的编码方式
      * @param out 输出流
      */
      public     static     void    processTemplate(String templatePath, String templateName, String templateEncoding, Map<?,?> root, Writer out){
          try    {
             Configuration config= new    Configuration();
             File file= new    File(templatePath);
              //设置要解析的模板所在的目录，并加载模板文件
             config.setDirectoryForTemplateLoading(file);
              //设置包装器，并将对象包装为数据模型
             config.setObjectWrapper( new    DefaultObjectWrapper());

              //获取模板,并设置编码方式，这个编码必须要与页面中的编码格式一致
             Template template=config.getTemplate(templateName,templateEncoding);
              //合并数据模型与模板

             template.process(root, out);
             out.flush();
             out.close();
         }  catch    (IOException e) {
             e.printStackTrace();
         } catch    (TemplateException e) {
             e.printStackTrace();
         }

     }
 }

import java.io.File;
import java.io.IOException;
import java.io.Writer;
import java.util.Map;
 
import freemarker
.template.Configuration;
import freemarker
.template.DefaultObjectWrapper;
import freemarker
.template.Template;
import freemarker
.template.TemplateException;
/**
 * 
 * 模板工具类
 */
public class FreeMarkertUtil {
/**
 * @param templatePath 模板文件存放目录 
 * @param templateName 模板文件名称 
 * @param root 数据模型根对象
 * @param templateEncoding 模板文件的编码方式
 * @param out 输出流
 */
public static void processTemplate(String templatePath, String templateName, String templateEncoding, Map<?,?> root, Writer out){
try {
Configuration config=new Configuration();
File file=new File(templatePath);
//设置要解析的模板所在的目录，并加载模板文件
config.setDirectoryForTemplateLoading(file);
//设置包装器，并将对象包装为数据模型
config.setObjectWrapper(new DefaultObjectWrapper());
//获取模板,并设置编码方式，这个编码必须要与页面中的编码格式一致
Template template=config.getTemplate(templateName,templateEncoding);
//合并数据模型与模板
    template.process(root, out);
    out.flush();
    out.close();
} catch (IOException e) {
e.printStackTrace();
}catch (TemplateException e) {
e.printStackTrace();
}
} 
}

 

 

 import    java.io.OutputStreamWriter;
 import    java.util.HashMap;
 import    java.util.Map;

 /**
  *
  * 客户端测试模板输入类
  */
 public     class    RepeatTest {
      public     static     void    main(String[] args) {
         Map<String,Object> root= new    HashMap<String, Object>();

         root.put( "repeat"  ,  new    RepeatDirective());

         FreeMarkertUtil.processTemplate( "src/templates"  , "repeat.ftl"  ,  "UTF-8"  , root,  new    OutputStreamWriter(System.out));

     }
 }

import java.io.OutputStreamWriter;
import java.util.HashMap;
import java.util.Map;
 
/**
 * 
 * 客户端测试模板输入类
 */
public class RepeatTest {
public static void main(String[] args) {
Map<String,Object> root=new HashMap<String, Object>();
root.put("repeat", new RepeatDirective());
FreeMarkertUtil.processTemplate("src/templates","repeat.ftl", "UTF-8", root, new OutputStreamWriter(System.out));
}
}

 

 模板文件repeat.ftl如下：

 

 <#assign x =  1  >

 一个参数：
 < @repeat   count= 4  >
   Test ${x}
   <#assign x = x +  1  >
 </ @repeat  >

 二个参数：
 < @repeat   count= 3   hr= true   >
   Test
 </ @repeat  >

 循环变量：
 < @repeat   count= 3  ; cnt>
   ${cnt}. Test
 </ @repeat  >

<#assign x = 1>
 
一个参数：
<@repeat count=4>
  Test ${x}
  <#assign x = x + 1>
</@repeat>
二个参数：
<@repeat count=3 hr=true>
  Test
</@repeat>
循环变量：
<@repeat count=3; cnt>
  ${cnt}. Test
</@repeat>  

 

 输出结果：

Java代码

 一个参数：
   Test  1
   Test  2
   Test  3
   Test  4

 二个参数：
   Test
 <hr>  Test
 <hr>  Test

 循环变量：
    1  . Test
    2  . Test
    3  . Test