标签：jstl
由于本人之前并没有接触过jstl标签，说来也可笑，之前一直使用struts2标签。最近项目用到jstl，所以做些记录方便以后自己查看。
jstl的强大原因之一我认为就是他的自定义函数，我们可以在前端页面直接就调用了java后台的一些常用方法，这一点真是让我爱不释手好吗。废话不多说，接下来具体看看如何使用jstl的自定义函数。
首先jstl的jar包肯定是要导的，在这就不啰嗦了。
使用jstl自定义函数要做到以下几点：
1.定义的方法必须是public的并且是static的；
2.定义相应的tld文件在WEB-INF目录或其子目录下；
3.定义相应的自定义函数库<%@ taglib prefix="fns" uri="/WEB-INF/tlds/fns.tld" %>。
具体示例代码如下：
fns.tld文件
<?xml version="1.0" encoding="UTF-8" ?>
<taglib xmlns="http://java.sun.com/xml/ns/j2ee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-jsptaglibrary_2_0.xsd"
version="2.0">
<description>JSTL 1.1 functions library</description>
<display-name>JSTL functions sys</display-name>
<tlib-version>1.1</tlib-version>
<short-name>fns</short-name>
<uri>http://java.sun.com/jsp/jstl/functionss</uri>
<function>
<description>获取管理路径</description>
<name>getAdminPath</name>
<function-class>com.gisquest.djgx.common.config.Global</function-class>
<function-signature>java.lang.String getAdminPath()</function-signature>
<example>${fns:getAdminPath()}</example>
</function>
<function>
<description>获取网站路径</description>
<name>getFrontPath</name>
<function-class>com.gisquest.djgx.common.config.Global</function-class>
<function-signature>java.lang.String getFrontPath()</function-signature>
<example>${fns:getFrontPath()}</example>
</function>
<function>
<description>获取网站URL后缀</description>
<name>getUrlSuffix</name>
<function-class>com.gisquest.djgx.common.config.Global</function-class>
<function-signature>java.lang.String getUrlSuffix()</function-signature>
<example>${fns:getUrlSuffix()}</example>
</function>
<function>
<description>获取配置</description>
<name>getConfig</name>
<function-class>com.gisquest.djgx.common.config.Global</function-class>
<function-signature>java.lang.String getConfig(java.lang.String)</function-signature>
<example>${fns:getConfig(key)}</example>
</function>
<function>
<description>获取常量</description>
<name>getConst</name>
<function-class>com.gisquest.djgx.common.config.Global</function-class>
<function-signature>java.lang.Object getConst(java.lang.String)</function-signature>
<example>${fns:getConst(key)}</example>
</function>
<!-- UserUtils -->
<function>
<description>获取当前用户对象</description>
<name>getUser</name>
<function-class>com.gisquest.djgx.modules.sys.utils.UserUtils</function-class>
<function-signature>com.gisquest.djgx.modules.sys.entity.User getUser()</function-signature>
<example>${fns:getUser()}</example>
</function>
<function>
<description>根据ID获得用户对象</description>
<name>getUserById</name>
<function-class>com.gisquest.djgx.modules.sys.utils.UserUtils</function-class>
<function-signature>com.gisquest.djgx.modules.sys.entity.User getUserById(java.lang.String)</function-signature>
<example>${fns:getUserById(id)}</example>
</function>
<function>
<description>获取授权用户信息</description>
<name>getPrincipal</name>
<function-class>com.gisquest.djgx.modules.sys.utils.UserUtils</function-class>
<function-signature>com.gisquest.djgx.modules.sys.security.SystemAuthorizingRealm.Principal getPrincipal()</function-signature>
<example>${fns:getPrincipal()}</example>
</function>
<function>
<description>获取当前用户的菜单对象列表</description>
<name>getMenuList</name>
<function-class>com.gisquest.djgx.modules.sys.utils.UserUtils</function-class>
<function-signature>java.util.List getMenuList()</function-signature>
<example>${fns:getMenuList()}</example>
</function>
<function>
<description>获取当前用户的区域对象列表</description>
<name>getAreaList</name>
<function-class>com.gisquest.djgx.modules.sys.utils.UserUtils</function-class>
<function-signature>java.util.List getAreaList()</function-signature>
<example>${fns:getAreaList()}</example>
</function>
<function>
<description>获取当前用户的部门对象列表</description>
<name>getOfficeList</name>
<function-class>com.gisquest.djgx.modules.sys.utils.UserUtils</function-class>
<function-signature>java.util.List getOfficeList()</function-signature>
<example>${fns:getOfficeList()}</example>
</function>
<function>
<description>获取当前用户缓存</description>
<name>getCache</name>
<function-class>com.gisquest.djgx.modules.sys.utils.UserUtils</function-class>
<function-signature>java.lang.Object getCache(java.lang.String, java.lang.Object)</function-signature>
<example>${fns:getCache(cacheName, defaultValue)}</example>
</function>
<!-- DictUtils -->
<function>
<description>获取字典标签</description>
<name>getDictLabel</name>
<function-class>com.gisquest.djgx.modules.sys.utils.DictUtils</function-class>
<function-signature>java.lang.String getDictLabel(java.lang.String, java.lang.String, java.lang.String)</function-signature>
<example>${fns:getDictLabel(value, type, defaultValue)}</example>
</function>
<function>
<description>获取字典标签(多个)</description>
<name>getDictLabels</name>
<function-class>com.gisquest.djgx.modules.sys.utils.DictUtils</function-class>
<function-signature>java.lang.String getDictLabels(java.lang.String, java.lang.String, java.lang.String)</function-signature>
<example>${fns:getDictLabels(values, type, defaultValue)}</example>
</function>
<function>
<description>获取字典值</description>
<name>getDictValue</name>
<function-class>com.gisquest.djgx.modules.sys.utils.DictUtils</function-class>
<function-signature>java.lang.String getDictValue(java.lang.String, java.lang.String, java.lang.String)</function-signature>
<example>${fns:getDictValue(label, type, defaultValue)}</example>
</function>
<function>
<description>获取字典对象列表</description>
<name>getDictList</name>
<function-class>com.gisquest.djgx.modules.sys.utils.DictUtils</function-class>
<function-signature>java.util.List getDictList(java.lang.String)</function-signature>
<example>${fns:getDictList(type)}</example>
</function>
<!-- Encodes -->
<function>
<description>URL编码</description>
<name>urlEncode</name>
<function-class>com.gisquest.djgx.common.utils.Encodes</function-class>
<function-signature>java.lang.String urlEncode(java.lang.String)</function-signature>
<example>${fns:urlEncode(part)}</example>
</function>
<function>
<description>URL解码</description>
<name>urlDecode</name>
<function-class>com.gisquest.djgx.common.utils.Encodes</function-class>
<function-signature>java.lang.String urlDecode(java.lang.String)</function-signature>
<example>${fns:urlDecode(part)}</example>
</function>
<function>
<description>HTML编码</description>
<name>escapeHtml</name>
<function-class>com.gisquest.djgx.common.utils.Encodes</function-class>
<function-signature>java.lang.String escapeHtml(java.lang.String)</function-signature>
<example>${fns:escapeHtml(html)}</example>
</function>
<function>
<description>HTML解码</description>
<name>unescapeHtml</name>
<function-class>com.gisquest.djgx.common.utils.Encodes</function-class>
<function-signature>java.lang.String unescapeHtml(java.lang.String)</function-signature>
<example>${fns:unescapeHtml(html)}</example>
</function>
<!-- StringUtils -->
<function>
<description>从后边开始截取字符串</description>
<name>substringAfterLast</name>
<function-class>org.apache.commons.lang3.StringUtils</function-class>
<function-signature>java.lang.String substringAfterLast(java.lang.String, java.lang.String)</function-signature>
<example>${fns:substringAfterLast(str,separator)}</example>
</function>
<function>
<description>判断字符串是否以某某开头</description>
<name>startsWith</name>
<function-class>org.apache.commons.lang3.StringUtils</function-class>
<function-signature>boolean startsWith(java.lang.CharSequence, java.lang.CharSequence)</function-signature>
<example>${fns:startsWith(str,prefix)}</example>
</function>
<function>
<description>判断字符串是否以某某结尾</description>
<name>endsWith</name>
<function-class>org.apache.commons.lang3.StringUtils</function-class>
<function-signature>boolean endsWith(java.lang.CharSequence, java.lang.CharSequence)</function-signature>
<example>${fns:endsWith(str,suffix)}</example>
</function>
<function>
<description>缩写字符串，超过最大宽度用“...”表示</description>
<name>abbr</name>
<function-class>com.gisquest.djgx.common.utils.StringUtils</function-class>
<function-signature>java.lang.String abbr(java.lang.String, int)</function-signature>
<example>${fns:abbr(str,length)}</example>
</function>
<function>
<description>替换掉HTML标签后缩写字符串，超过最大宽度用“...”表示</description>
<name>rabbr</name>
<function-class>com.gisquest.djgx.common.utils.StringUtils</function-class>
<function-signature>java.lang.String rabbr(java.lang.String, int)</function-signature>
<example>${fns:rabbr(str,length)}</example>
</function>
<function>
<description>替换掉HTML标签</description>
<name>replaceHtml</name>
<function-class>com.gisquest.djgx.common.utils.StringUtils</function-class>
<function-signature>java.lang.String replaceHtml(java.lang.String)</function-signature>
<example>${fns:replaceHtml(html)}</example>
</function>
<function>
<description>转换为JS获取对象值，生成三目运算返回结果。</description>
<name>jsGetVal</name>
<function-class>com.gisquest.djgx.common.utils.StringUtils</function-class>
<function-signature>java.lang.String jsGetVal(java.lang.String)</function-signature>
<example>${fns:jsGetVal('row.user.id')} 返回：!row?'':!row.user?'':!row.user.id?'':row.user.id</example>
</function>
<!-- DateUtils -->
<function>
<description>获取当前日期</description>
<name>getDate</name>
<function-class>com.gisquest.djgx.common.utils.DateUtils</function-class>
<function-signature>java.lang.String getDate(java.lang.String)</function-signature>
<example>${fns:getDate(pattern)}</example>
</function>
<function>
<description>获取过去的天数</description>
<name>pastDays</name>
<function-class>com.gisquest.djgx.common.utils.DateUtils</function-class>
<function-signature>long pastDays(java.util.Date)</function-signature>
<example>${fns:pastDays(date)}</example>
</function>
<!-- JsonMapper -->
<function>
<description>对象转换JSON字符串</description>
<name>toJson</name>
<function-class>com.gisquest.djgx.common.mapper.JsonMapper</function-class>
<function-signature>java.lang.String toJsonString(java.lang.Object)</function-signature>
<example>${fns:toJson(object)}</example>
</function>
</taglib>
相应后台工具代码：
package com.gisquest.djgx.modules.sys.utils;
import java.util.List;
import java.util.Map;
import org.apache.commons.lang3.StringUtils;
import com.gisquest.djgx.common.utils.CacheUtils;
import com.gisquest.djgx.common.utils.SpringContextHolder;
import com.gisquest.djgx.modules.sys.dao.DictDao;
import com.gisquest.djgx.modules.sys.entity.Dict;
import com.google.common.collect.Lists;
import com.google.common.collect.Maps;
/**
* 字典工具类
* @author Administrator
* @version 2013-5-29
*/
public class DictUtils {
private static DictDao dictDao = SpringContextHolder.getBean(DictDao.class);
public static final String CACHE_DICT_MAP = "dictMap";
public static String getDictLabel(String value, String type, String defaultValue){
if (StringUtils.isNotBlank(type) && StringUtils.isNotBlank(value)){
for (Dict dict : getDictList(type)){
if (type.equals(dict.getType()) && value.equals(dict.getValue())){
return dict.getLabel();
}
}
}
return defaultValue;
}
public static String getDictLabels(String values, String type, String defaultValue){
if (StringUtils.isNotBlank(type) && StringUtils.isNotBlank(values)){
List<String> valueList = Lists.newArrayList();
for (String value : StringUtils.split(values, ",")){
valueList.add(getDictLabel(value, type, defaultValue));
}
return StringUtils.join(valueList, ",");
}
return defaultValue;
}
public static String getDictValue(String label, String type, String defaultLabel){
if (StringUtils.isNotBlank(type) && StringUtils.isNotBlank(label)){
for (Dict dict : getDictList(type)){
if (type.equals(dict.getType()) && label.equals(dict.getLabel())){
return dict.getValue();
}
}
}
return defaultLabel;
}
public static List<Dict> getDictList(String type){
@SuppressWarnings("unchecked")
Map<String, List<Dict>> dictMap = (Map<String, List<Dict>>)CacheUtils.get(CACHE_DICT_MAP);
if (dictMap == null){
dictMap = Maps.newHashMap();
for (Dict dict : dictDao.findAllList()){
List<Dict> dictList = dictMap.get(dict.getType());
if (dictList != null){
dictList.add(dict);
}else{
dictMap.put(dict.getType(), Lists.newArrayList(dict));
}
}
CacheUtils.put(CACHE_DICT_MAP, dictMap);
}
List<Dict> dictList = dictMap.get(type);
if (dictList == null){
dictList = Lists.newArrayList();
}
return dictList;
}
}
前台调用：
<div class="control-group">
<label class="control-label" for="flag">定时类型:</label>
<div class="controls">
<form:select path="flag" onchange="updateClass()">
<form:options items="${fns:getDictList('696d7f3d414940b79aa962b8c30f989f')}" itemLabel="label" itemValue="value" htmlEscape="false"/>
</form:select>
</div>
</div>版权声明：本文为博主原创文章，未经博主允许不得转载。
标签：jstl
原文地址：http://blog.csdn.net/nethackatschool/article/details/47082469
