它的结构是:

<c:choose>
   <c:when test="${..}">...</c:when> <!-- if condition -->
   <c:when test="${..}">...</c:when> <!-- else if condition -->
   <c:otherwise>...</c:otherwise>    <!-- else condition -->
</c:choose>

如果条件不是很昂贵，我有时更喜欢简单地使用两个不同的<c: If标记——这样更容易阅读。

它的结构是:

<c:choose>
   <c:when test="${..}">...</c:when> <!-- if condition -->
   <c:when test="${..}">...</c:when> <!-- else if condition -->
   <c:otherwise>...</c:otherwise>    <!-- else condition -->
</c:choose>

如果条件不是很昂贵，我有时更喜欢简单地使用两个不同的<c: If标记——这样更容易阅读。

<%@ taglib prefix='c' uri='http://java.sun.com/jsp/jstl/core' %>
<c:set var="val" value="5"/>
<c:choose> 
  <c:when test="${val == '5'}">
    Value is 5
  </c:when>
  <c:otherwise>
    Value is not 5
  </c:otherwise>
</c:choose>

<c:choose>
<c:when test="${not empty userid and userid ne null}">
      <sql:query dataSource="${dbsource}" var="usersql">
                SELECT * FROM newuser WHERE ID = ?;
                <sql:param value="${param.userid}" />
      </sql:query>
 </c:when>
 <c:otherwise >
       <sql:query dataSource="${dbsource}" var="usersql">
                 SELECT * FROM newuser WHERE username = ?;
                 <sql:param value="${param.username}" />
       </sql:query>                              
  </c:otherwise>

<%@ taglib prefix='c' uri='http://java.sun.com/jsp/jstl/core' %>
<c:set var="isiPad" value="value"/>
<c:choose>
   <!-- if condition -->
   <c:when test="${...}">Html Code</c:when> 
   <!-- else condition -->
   <c:otherwise>Html code</c:otherwise>   
</c:choose>

<c:if test="${condition1 && condition2 && condition3}" var="condition">
    //if
</c:if>
<c:if test="${!condition}">
    //else
</c:if>

这是在变量中使用if条件的另一种方式。