JSTL foreach循环生成太多空行（空白HTML空间）

Question

我通过从HTML5（使用JSP循环）列表中读取数据，在ServletContext中生成JSTL foreach页面菜单项。这样我就会创建<nav> HTML5标记的内容。

这很好用，我正在寻找我想要的页面。但是，当我查看HTML页面源（从JSP生成）时，在foreach循环中生成的空行（空格）太多。

这是生成此内容的代码：

<li><a href="#">Categories</a>
    <ul class="droprightMenu">
        <li><a href="#">All</a>
            <ul class="droprightMenu">

                <!-- first list iteration, top level categories, level1  -->
                <c:forEach items="${categories }" var="catLevel1">

                    <c:if test="${catLevel1.getParentCategory()==null }">
                        <li><a href="#">${catLevel1.getName() }</a> <!-- second list iteration, level 2 categories, 
                                     parentCategory is level1  -->
                            <ul class="droprightMenu">
                                <c:forEach items="${categories }" var="catLevel2">

                                    <c:if
                                        test="${catLevel2.getParentCategory().getId()==catLevel1.getId() }">
                                        <li><a href="#">${catLevel2.getName() }</a> <!-- third list iteration, level3 categories
                                                      parentCategory is level2  -->
                                            <ul class="droprightMenu">
                                                <c:forEach items="${categories }" var="catLevel3">

                                                    <c:if
                                                        test="${catLevel3.getParentCategory().getId()==catLevel2.getId() }">
                                                        <li><a href="#">${catLevel3.getName() }</a></li>
                                                    </c:if>

                                                </c:forEach>
                                            </ul></li>
                                    </c:if>

                                </c:forEach>
                            </ul></li>
                    </c:if>
                </c:forEach>

            </ul></li>
    </ul></li>

，生成的内容如下所示：

    <li><a href="#">Categories</a>
        <ul class="droprightMenu">
            <li><a href="#">All</a>
                <ul class="droprightMenu">

                    <!-- first list iteration, top level categories, level1  -->



                            <li><a href="#">Sports</a> <!-- second list iteration, level 2 categories, 
                                         parentCategory is level1  -->
                                <ul class="droprightMenu">















                                            <li><a href="#">Football</a> <!-- third list iteration, level3 categories
                                                      parentCategory is level2  -->
                                                <ul class="droprightMenu">

















































                                                </ul></li>





                                            <li><a href="#">Basketball</a> <!-- third list iteration, level3 categories
                                                      parentCategory is level2  -->
                                                <ul class="droprightMenu">

















































                                                </ul></li>





                                            <li><a href="#">Hockey</a> <!-- third list iteration, level3 categories
                                                      parentCategory is level2  -->
                                                <ul class="droprightMenu">

















































                                                </ul></li>



























                                </ul></li>




                            <li><a href="#">Politics</a> <!-- second list iteration, level 2 categories, 
                                         parentCategory is level1  -->
                                <ul class="droprightMenu">

















































                                </ul></li>




                            <li><a href="#">IT</a> <!-- second list iteration, level 2 categories, 
                                         parentCategory is level1  -->
                                <ul class="droprightMenu">



























                                            <li><a href="#">Software</a> <!-- third list iteration, level3 categories
                                                          parentCategory is level2  -->
                                                <ul class="droprightMenu">

















































                                                </ul></li>





                                            <li><a href="#">Hardware</a> <!-- third list iteration, level3 categories
                                                          parentCategory is level2  -->
                                                <ul class="droprightMenu">

















































                                                </ul></li>





                                            <li><a href="#">Programming</a> <!-- third list iteration, level3 categories
                                                          parentCategory is level2  -->
                                                <ul class="droprightMenu">











































                                                            <li><a href="#">Java</a></li>





                                                            <li><a href="#">C#</a></li>



                                                </ul></li>





                                            <li><a href="#">Tutorials</a> <!-- third list iteration, level3 categories
                                                          parentCategory is level2 -->
                                                <ul class="droprightMenu">

















































                                                </ul></li>











                                </ul></li>






























                </ul></li>
        </ul></li>

如何防止产生这些空行？因此页面源标记看起来很正常。