<c:choose> <c:when test="${!sessionScope.user eq null}"> <li><a href="#">${sessionScope.user.username}</a></li> <li><a href="http://www.mamicode.com/loginOut">注销</a></li> </c:when> <c:otherwise> <li><a href="http://www.mamicode.com/login">登录</a></li> <li><a href="http://www.mamicode.com/regist">注册</a></li> </c:otherwise> </c:choose>

jsp+jstl实现登录验证