判断Map是否为空

判断Map是否为空1在JSP页面中引入sun的核心标签库<% taglib uri = " prefix="c" %>2在JSP页面中引入sun的函数标签库<% taglib uri = "http:/java.s un .com/jsp/jstl/fu nctio ns" pr efix="f n"%>3判断是否为空<c:if test="$!empty map"></c:if>|4判断长度大于0<c:if test="$fn:length(map)>0"></c:if>注：fn:length(obj),对于空对象也会返回05例子：将request传入的hashmap显示在表格中<% page lan guage="java" conten tType="text/html; cha rset=utf-8"pageE ncod in g = "utf-8" impo rt="java.util.HashMap,java.util.Ite rator "%><% taglib uri = " prefix="c" %> <!-引入 sun 的核心 标签库-><% taglib uri = " prefix="fn"%> <!-引入 sun 的函数标签库->v!DOCTYPE html PUBLIC "-/W3C/DTD HTML 4.01 Tran siti on al/EN" "http:/www.w3.o rg/TR/html4/loose.dtd">vhtml>vhead>vmeta http-equiv="Content-Type" content="text/html; charset=utf-8">vtitle >显示jsp传递的参数-使用标签库v/title>v/head>vbody>vce nter> vh1 > 传递的参数 v/h1>v/ce nte r>vhr/>vc:choose>vc:when test="$fn:length(requestScope.paramMap)>0">vtable border="1">vt r> vth> 参数名 v/th>vth> 参数值 v/th>v/t r>vc:forEach items="$requestScope.paramMap" var= "map">vtr> vtd>$map.keyv/td>vtd>$map.valuev/td>v/t r>v/c:fo rEach>v/table>v/c:whe n>vc:othe rwise>vc:out value="没有在 request 中传递 paramMap 属性"/>vbr/>vp>paramMap 大小为:$fn:length(requestScope.paramMap)v/p>v/c:othe rwise>v/c:choose> v/body> v/html>