JavaWeb -- 自定义标签实例， 防盗链， JSTL 核心标签
1. 自定义标签应用实例1： 防盗链
标签处理类
public class RefererTag extends SimpleTagSupport {
private String site;
private String page;
public void setSite(String site) {
this.site = site;
}
public void setPage(String page) {
this.page = page;
}
@Override
public void doTag() throws JspException, IOException {
PageContext context = (PageContext) this.getJspContext();
HttpServletRequest request = (HttpServletRequest) context.getRequest();
HttpServletResponse response = (HttpServletResponse) context.getResponse();
String referer = request.getHeader("referer"); //获得来访者链接
//System.out.println("referer: " + referer);
if(referer==null || !referer.startsWith(site)) //来访者 是盗链 重定向到首页
{
if(page.startsWith(request.getContextPath()))
response.sendRedirect(page);
else if(page.startsWith("/"))
response.sendRedirect(request.getContextPath() + page);
else
response.sendRedirect(request.getContextPath() + "/" + page);
throw new SkipPageException(); //是盗链 后面页面内容不显示
}
}
}
tld文件
<tag>
<name>RefererTag</name>
<tag-class>com.kevin.web.tag.RefererTag</tag-class>
<body-content>empty</body-content>
<attribute>
<name>site</name>
<required>true</required>
<rtexprvalue>true</rtexprvalue>
</attribute>
<attribute>
<name>page</name>
<required>true</required>
<rtexprvalue>true</rtexprvalue>
</attribute>
</tag>
应用：该网页不能直接访问， 必须从首页超链接跳转进来
<kevin:RefererTag site="http://192.168.1.113" page="index.jsp" />
2. JSTL核心标签使用 示例
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%@taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
<title>JSTL测试</title>
</head>
<body>
<br /> ----------------- c:out 标签 ------------------------------------<br />
<c:out value="<a href=''> </a>" default="默认值" escapeXml="true"></c:out>
<br /> ----------c:set 标签 可操作各个域 javabean map集合-------------<br />
<c:set var="data1" value="data1xxx" scope="page" />
${data1} <br />
<%
Map map = new HashMap();
request.setAttribute("map", map);
%>
<c:set target="${map}" property="dd" value="xxxxx"></c:set>
${map.dd} <br />
<br /> -------- c:remove 标签 从域中删除域中属性------------------<br />
${data1} <br />
<c:remove var="data1" />
${data1} <br />
<br /> -------- c:catch 标签 抓取异常-----------------<br />
<c:catch var="exception">
<%
int i = 5/0;
%>
</c:catch>
${exception.message} <br />
<br /> -------- c:if 标签 条件判断-----------------<br />
<c:if var="result" test="${user==null}">
c:if test <br/>
</c:if>
${result} <br />
<br /> -------- c:choose 标签 条件判断-----------------<br />
<c:choose>
<c:when test="${user!=null}">用户登录<br/> </c:when>
<c:otherwise>无用户登录<br /> </c:otherwise>
</c:choose>
<br /> -------- c:foreach 标签 -----------------<br />
<%
Map map2 = new HashMap();
map2.put("aaaa", "aaaaa");
map2.put("1111", "11111");
request.setAttribute("map2", map2);
%>
<!-- var对应的是 每次获得的对象 存到域里， 对应的关键字 是var -->
<c:forEach var="entry" items="${map2}">
${entry.key} : ${entry.value} <br />
</c:forEach>
<c:forEach var="num" begin="1" end="9" step="1">
${num} <br />
</c:forEach>
<br /> -------- c:foreach varStatus实现表格间色---------------<br />
<%
List list = new ArrayList();
list.add("aaaaaaaaaa");
list.add("bbbbbbbbbb");
list.add("cccccccccc");
list.add("dddddddddd");
list.add("eeeeeeeeee");
request.setAttribute("list", list);
%>
<style>
.even{background-color: red;}
.odd{background-color: green;}
tr:hover{background-color: blue;}
</style>
<%-- varStatus获取到一个对象，该对象记录有是第几次迭代--%>
<table border="1px" width="30%">
<c:forEach var="row" items="${list}" varStatus="status">
<tr class="${status.count%2==0?'even':'odd'}">
<td>${row}</td>
</tr>
</c:forEach>
</table>
<br /> --- c:url 构造一个URL地址，并且会带上sessionID，参数自动编码 -----<br />
<c:url var="url" value="/index.jsp">
<c:param name="name">中国</c:param>
</c:url>
<a href="${url}" >点点</a> <br />
<br /> -------- c:forTokens 字符串分割---------------<br />
<%
request.setAttribute("data2", "a,b,c,d,e,f");
%>
<c:forTokens var="str" items="${data2}" delims=",">
${str} <br />
</c:forTokens>
<br /> -------- c:redirect 重定向---------------<br />
<%--<c:redirect url="/index.jsp"></c:redirect> --%>
</body>
</html>
