在JSP中使用自定义标签防止盗链（传智播客学习笔记）

来源：互联网发布：mac如何解压缩rar 编辑：程序博客网时间：2024/06/05 16:38

1.先编写此类。

package itcast.lxd.web.simpleTagAttrib;import java.io.IOException;import java.util.Date;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import javax.servlet.jsp.JspException;import javax.servlet.jsp.PageContext;import javax.servlet.jsp.SkipPageException;import javax.servlet.jsp.tagext.JspFragment;import javax.servlet.jsp.tagext.SimpleTagSupport;public class referDemo extends SimpleTagSupport{String webSiteReferer ;String webIndex;public void setWebSiteReferer(String webSiteReferer){this.webSiteReferer = webSiteReferer;}public void setWebIndex(String webIndex){this.webIndex = webIndex;}public void doTag() throws JspException, IOException{PageContext pageContext =(PageContext)this.getJspContext();HttpServletRequest request =(HttpServletRequest)pageContext.getRequest();HttpServletResponse response =(HttpServletResponse)pageContext.getResponse();if(request.getHeader("referer")==null||!request.getHeader("referer").startsWith(webSiteReferer)){response.sendRedirect(webIndex);throw new SkipPageException();}else{}}}

这个标签带两个属性，一个是site也就是这个防盗链需要来自什么地方的连接才能够访问，第二个page的意思是如果是其他位置访问本页面需要跳转到哪里去。

JspContext必须转型为pageContext才能获得需要的几个对象，然后根据浏览器带过来的referer头就可以知道访问位置，然后对于标签的友好型，还可以自己设置输入格式，下面需要在tld文件中描述一下这个标签

<?xml version="1.0" encoding="UTF-8" ?><!DOCTYPE taglib  PUBLIC "-//Sun Microsystems, Inc.//DTD JSP Tag Library 1.2//EN"  "http://java.sun.com/dtd/web-jsptaglibrary_1_2.dtd"><taglib>  <tlib-version>1.0</tlib-version>  <jsp-version>1.2</jsp-version>  <short-name>refererTest</short-name>  <uri>http://www.itcast.lxd.com.referer</uri>  <display-name>JSTL core</display-name>  <description>JSTL 1.0 core library</description>    <tag>    <name>referExample</name>    <tag-class>itcast.lxd.web.simpleTagAttrib.referDemo</tag-class>    <body-content>empty</body-content>    <attribute>      <name>webSiteReferer</name>      <required>true</required>      <rtexprvalue>true</rtexprvalue>    </attribute>     <attribute>      <name>webIndex</name>      <required>true</required>      <rtexprvalue>true</rtexprvalue>    </attribute>  </tag></taglib>

3.0我使用此标签

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%><%@taglib  uri="http://www.itcast.lxd.com.referer" prefix="referTest" %><%String path = request.getContextPath();String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";%><referTest:referExample webSiteReferer="http://localhost" webIndex="http://www.baidu.com"/><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><html>  <head>    <base href="<%=basePath%>">        <title>My JSP 'refertest.jsp' starting page</title>  </head>  <body>    This is my JSP page. <br>     <font color="red" size="7">     这里是我的隐私日记啊，可以防盗链啊，你们一般人看不到啊 嘎嘎嘎嘎      </font>  </body></html>