<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<%@taglib prefix="fn" uri="http://java.sun.com/jsp/jstl/functions" %>
<%@taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>string</title>
</head>
<body>
<form>
一个输入框：<input type="text" name="v">
<input type="submit" value="ok">
<c:set var="s" value="${param.v}"></c:set>
</form>
Before：<c:out value="${s}"></c:out><br>
<c:if test="${not empty s}">
<c:forEach var="i" begin="0" end="${fn:length(s)-1}">
<c:set var="ns" value="${fn:substring(s,i,i+1)}${ns}"></c:set>
</c:forEach>
</c:if>
After：${ns}
</body>
</html>
