jstl foreach标签

Posted 2020-06-17

forEach标签

forEach标签用来循环.

属性:

* var :定义循环变量

* begin :从哪开始

* end :到哪结束

* step :递增

* items :遍历的内容

* varStatus :记录循环变量

代码:

<h1>JSTL的forEach标签</h1>

<h3>遍历数组</h3>

<%

String[] arrs = { "小默", "小房", "美美" };

pageContext.setAttribute("arrs", arrs);

%>

<!-- 使用增强for for(类型 遍量:循环内容){} -->

<!-- 

for(String name:arrs){}

-->

<c:forEach var="name" items="${ arrs }">

${ name }

</c:forEach>

<h3>遍历List集合</h3>

<%

List<String> list = new ArrayList<String>();

list.add("苍老师");

list.add("美美老师");

pageContext.setAttribute("list", list);

%>

<c:forEach var="name" items="${ list }">

${ name }

</c:forEach>

<h3>遍历Map结合</h3>

<%

Map<String,String> map = new HashMap<String,String>();

map.put("aaa", "凤姐");

map.put("bbb", "芙蓉");

map.put("ccc", "如花");

pageContext.setAttribute("map", map);

%>

<c:forEach var="entry" items="${ map }">

${ entry.key } --- ${ entry.value }

</c:forEach>

<h3>遍历对象的集合</h3>

<%

List<Person> pList = new ArrayList<Person>();

pList.add(new Person("美美",32));

pList.add(new Person("小边",18));

pList.add(new Person("凤姐",28));

pageContext.setAttribute("pList", pList);

%>

<c:forEach var="p" items="${ pList }">

${ p.name } --- ${ p.age }

</c:forEach>

<h3>输出1到10</h3>

<c:forEach var="i" begin="1" end="10" step="1">

${ i }

</c:forEach>

<h3>从1加到100的和</h3>

<c:set var="sum" value="0" scope="page"></c:set>

<c:forEach var="i" begin="1" end="100" step="1">

<c:set var="sum" value="${ sum + i }" scope="page"></c:set>

</c:forEach>

${ sum }

<h3>从100-200遍历 每次递增 3 到第三个数变成红色</h3>

<c:forEach var="i" begin="100" end="200" step="3" varStatus="status">

<c:if test="${ status.count % 3 == 0}">

<font color="red">${ i }</font>

</c:if>

<c:if test="${ status.count % 3 != 0}">

${ i }

</c:if>

</c:forEach>