在JSP中使用自定义标签防止盗链（传智播客学习笔记）

1.先编写此类。
[java]
package itcast.lxd.web.易做图TagAttrib;
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
[html]
<?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.易做图TagAttrib.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

[html]
<%@ 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>

作者：lixiaodaoaaa

补充：Web开发 , Jsp ,