jsp<c:if>与EL表达式

Question

怎么截取EL表达式的内容。 
<c:forEach items="${ studyExp}" var = "studyExp">
           <tr>
                   <td class="tab_td_content">${studyExp.title }</td>
           <td class="tab_td_content">${studyExp.info }</td>
           <td class="tab_td_content">
          
                                     表达式${studyExp.content}的内容过长，想截取前四位
           <c:if test="${studyExp.content}">
          
           </c:if>
          
           </td>
           <td class="tab_td_content">${studyExp.classes }</td>
           <td class="tab_td_content">${studyExp.crdt }</td>
           <td class="tab_td_content">${studyExp.crusr}</td>
           <td class="tab_td_content">
           <img src="${sysPath}/img/list/edt.gif" width="16" height="16" /><a href="initUpdate.jspx?id=${studyExp.id }&page=${PAGE }">[编辑]</a>
           <img src="${sysPath}/img/list/del.gif" width="16" height="16" /><a href="updStudyExpAction.jspx?id=${studyExp.id }&method=del" onclick="return confirm('确定要删除此条记录')">[删除]</a>
           </td>
           </tr>
          </c:forEach>

Answer 1

可以用El函数 
<%@tablib uri="http://java.sun.com/jsp/jstl/functions" prefix="fn" %> 
上面的 uri 根据你的实际情况定。 ${fn:substring("你要截取的字符串"),beginIndex,endIndex} 

Answer 2

二楼正解，刚才已查到
<c:if test="${fn:length(studyExp.content) >10}"> 
          "${fn:substring(studyExp.content10)}........"
 </c:if>

Answer 3

${fn:substring("你要截取的字符串"),beginIndex,endIndex}   就是这个！只要把jstl包导进来就可以了！