参考：
http://grails.org/doc/latest/ref/Tags/select.html
http://freemarker.sourceforge.net/
?
调用：
<@d_select id="type_4" optionKey="position" optionValue="id" list=adSpaceBoList callBack="test();" value="4f0eabc9073c1f0de52b25d2" ></@d_select> 指定list对象名：list=adSpaceBoList;选项key对应集合中的属性：optionKey="position";选项value对应集合中的属性:optionValue="id"；
?
实现类：
implements TemplateDirectiveModel ；
public void execute
(Environment env, Map params, TemplateModel[] loopVars, TemplateDirectiveBody body)
??? ??? ??? throws TemplateException, IOException {
// id
??? ??? String id = MapUtils.getString(params, "id", "selectId");
// multiple
boolean multiple = Boolean.valueOf(MapUtils.getString(params, "multiple"));
// onEventName：默认有callback时为onChange
??? ??? String onEventName = MapUtils.getString(params, "onEventName","onChange");
?
Map<String, Object> templateContext = new HashMap<String, Object>();
//list
??? ??? Object temp = params.get("list");
??? ??? if(temp instanceof SimpleSequence){
??? ??? ??? SimpleSequence lists = (SimpleSequence) params.get("list");
??? ??? ??? templateContext.put("list",lists.toList());
??? ??? }
??? ???
??? ??? //strList
??? ??? String strList = MapUtils.getString(params, "strList");// strList : 文字:1,图片:2
??? ??? if(StringUtils.isNotBlank(strList)){
??? ??? ??? if(StringUtils.isNotBlank(strList)){
??? ??? ??? ??? templateContext.put("strList", Arrays.asList(strList.split(",")));
??? ??? ??? }
??? ??? }
??? ???
??? ??? //map
??? ??? SimpleHash map=(SimpleHash)params.get("map");
??? ??? if(null!=map){
??? ??? ??? templateContext.put("map",map.toMap());
??? ??? }
?
templateContext.put("id", id);
//.....
?
??????? Template template = env.getConfiguration().getTemplate("/ftl/select.ftl");
??? ??? template.process(templateContext, env.getOut());
}
?
页面：
eval：把字符串当做ftl代码处理；处理后对象的值要以string的length来判断，如果直接用??,则对象为空 ;
?
<#list list as obj>
??? ??? <#if obj??>
??? ??? ??? <#assign keys = ('obj.'+ optionKey) >
??? ??? ??? <#assign values = ('obj.'+ optionValue) >
??? ??? ??? <#if ((values?eval)?length gt 0 && (keys?eval)?length gt 0) >
??? ??? ??? ??? <option value="${values?eval}" <#if ((value??)&& value == values?eval) >selected</#if>>${keys?eval!''}</option>
??? ??? ??? </#if>
??? ??? </#if>
??? </#list>
?
最后，还要在项目里注册自定义的标签；
注册：
sothis.properties
sothis.freemarker.directive.d_select.class=com.fangjia.bkoff.util.SelectDirective
?
底层(部分)：
private SothisConfig config;
?
String configLocation = filterConfig.getInitParameter("configLocation");
??? ??? ??? ??? if (null == configLocation) {
??? ??? ??? ??? ??? configLocation = "sothis.properties";
??? ??? ??? ??? }
??? ??? ??? ??? config = SothisConfig.initConfig(configLocation);