JSP：自定义标签之防盗链标签开发

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使用标签控制页面逻辑案例

<%@ page language="java" pageEncoding="UTF-8"%>

<%@taglib uri ="/jsp2-tagexample"prefix="fix"%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTDHTML 4.01 Transitional//EN">

<fix:referersite="http://localhost"page="/index.jsp"></fix:referer>

<html>

。。。

public class RefererTag extends SimpleTagSupport {

private String page;

private String site;

public void setPage(String page) {

this.page = page;

}

public void setSite(String site) {

this.site = site;

}

@Override

public void doTag() throws JspException, IOException {

PageContext pageContext=(PageContext) this.getJspContext();

HttpServletRequest request=(HttpServletRequest) pageContext.getRequest();

HttpServletResponse response= (HttpServletResponse) pageContext.getResponse();

String referer=request.getHeader("referer");

if(referer==null || !referer.startsWith(site)){

String cp=request.getContextPath();

if(page.startsWith(cp))

{ response.sendRedirect(page);

}else if (page.startsWith("/")) {

response.sendRedirect(cp+page);

}else

{

response.sendRedirect(cp+"/"+page);

}

throw new SkipPageException();

}

else

super.doTag();

}

<?xml version="1.0" encoding="UTF-8" ?>

<taglib xmlns="http://java.sun.com/xml/ns/j2ee"

xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-jsptaglibrary_2_0.xsd"

version="2.0">

<description>A tag library exercising SimpleTag handlers.</description>

<tlib-version>1.0</tlib-version>

<short-name>SimpleTagLibrary</short-name>

<uri>/jsp2-tagexample</uri>

<tag>

<name>referer</name>

<tag-class>cn.itcast.web.tag.eaxmple.RefererTag</tag-class>

<body-content>empty</body-content>

<attribute>

<name>site</name>

<required>yes</required>

</attribute>

<attribute>

<name>page</name>

<required>yes</required>

<rtexprvalue>true</rtexprvalue>

</attribute>

</tag>

</taglib>

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