首先看一个实实在在的项目文档
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<c:if test="${! empty testUnit.crop_name}"><p class="search_p clearfix"><span class="search_left" style="width:30%"><font color=green>【作物名称】</font></span><span class="search_right" style="width:65%">${testUnit.crop_name }</span></p></c:if>
<c:if test="${! empty testUnit.service_item}"><p class="search_p clearfix"><span class="search_left" style="width:30%"><font color=green>【服务项目】</font></span><span class="search_right" style="width:65%">${testUnit.service_item } ${testUnit.service_item_son }</span></p></c:if>
<c:if test="${! empty testUnit.method}"><p class="search_p clearfix"><span class="search_left" style="width:30%"><font color=green>【测试方法】</font></span><span class="search_right" style="width:65%">${testUnit.method }</span></p></c:if>
<c:if test="${! empty testUnit.wait_data}"><p class="search_p clearfix"><span class="search_left" style="width:30%"><font color=green>【等待时间】</font></span><span class="search_right" style="width:65%">${testUnit.wait_data }</span></p></c:if>
<c:if test="${! empty testUnit.cost}"><p class="search_p clearfix"><span class="search_left" style="width:30%"><font color=green>【费用】</font></span><span class="search_right" style="width:65%">${testUnit.cost }</span></p></c:if>
<c:if test="${! empty testUnit.name}"><p class="search_p clearfix"><span class="search_left" style="width:30%"><font color=green>【单位名称】</font></span><span class="search_right" style="width:65%">${testUnit.name }</span></p></c:if>
<c:if test="${! empty testUnit.address}"><p class="search_p clearfix"><span class="search_left" style="width:30%"><font color=green>【地址】</font></span><span class="search_right" style="width:65%">${testUnit.address }</span></p></c:if>
<c:if test="${! empty testUnit.contactor}"><p class="search_p clearfix"><span class="search_left" style="width:30%"><font color=green>【联系人】</font></span><span class="search_right" style="width:65%">${testUnit.contactor }</span></p></c:if>
<c:if test="${! empty testUnit.phone_number}"><p class="search_p clearfix"><span class="search_left" style="width:30%"><font color=green>【电话】</font></span><span class="search_right" style="width:65%">${testUnit.phone_number }</span></p></c:if>
<c:if test="${! empty testUnit.introduction}"><p class="search_p clearfix"><span class="search_tt"><font color=green>【测试单位简介】</font></span></p>
<p class="search_p clearfix"><span class="search_tt">${testUnit.introduction}</span></p></c:if>
<p class="search_p clearfix"><span class="search_left" style="width:30%"><font color=green>【国家】</font></span><span class="search_right" style="width:65%">${testUnit.country }</span></p>
<p class="search_p clearfix"><span class="search_left" style="width:30%"><font color=green>【地区】</font></span><span class="search_right" style="width:65%">${testUnit.area_province } ${testUnit.area_city } ${testUnit.area_county }</span></p>
<c:if test="${! empty testUnit.picture}"><p class="search_p clearfix"><span class="search_tt"><font color=green>【相关图片】</font></span></p>
<table width="90%" border="0" cellspacing="0" cellpadding="0" style="margin:12px auto 50px;">
<c:set value="${fn:split(testUnit.picture,';')}" var="pictures" />
<c:forEach items="${pictures }" var="pict" varStatus="s">
<tr>
<td ><img width="100%" height="65%" src="${pict }"></td>
</tr>
<tr>
<td> </td>
</tr>
</c:forEach>
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</html>总结一下其中的<c:if>的使用：
<c:if test="${! empty testUnit.crop_name}"><p class="search_p clearfix"><span class="search_left" style="width:30%"><font color=green>【作物名称】</font></span><span class="search_right" style="width:65%">${testUnit.crop_name }</span></p></c:if>
意思是，如果testUnit.crop_name这个变量名称不为空的话，就显示出来，如果为空的话，就不显示。
原文：http://blog.csdn.net/itbuluoge/article/details/44588813