标签案例-开发防盗链标签

 1 package cn.itcast.web.tag;
 2 
 3 import java.io.IOException;
 4 
 5 import javax.servlet.http.HttpServletRequest;
 6 import javax.servlet.http.HttpServletResponse;
 7 import javax.servlet.jsp.JspException;
 8 import javax.servlet.jsp.PageContext;
 9 import javax.servlet.jsp.SkipPageException;
10 import javax.servlet.jsp.tagext.SimpleTagSupport;
11 
12 public class RefererTag extends SimpleTagSupport {
13 
14     private String site;
15     private String page;
16 
17     public void setSite(String site) {
18         this.site = site;
19     }
20 
21     public void setPage(String page) {
22         this.page = page;
23     }
24 
25     @Override
26     public void doTag() throws JspException, IOException {
27     
28         PageContext pageContext = (PageContext) this.getJspContext();
29         HttpServletRequest request = (HttpServletRequest) pageContext.getRequest();
30         HttpServletResponse response = (HttpServletResponse) pageContext.getResponse();
31         
32         //1.得到来访者referer
33         String referer = request.getHeader("referer");
34         if(referer==null||!referer.startsWith(site)){
35             if(page.startsWith(request.getContextPath())){
36                 response.sendRedirect(page);
37             }else if(page.startsWith("/")){
38                 response.sendRedirect(request.getContextPath()+page);
39             }else{
40                 response.sendRedirect(request.getContextPath()+"/"+page);
41             }
42             
43             throw new SkipPageException();
44         }
45         
46     }
47     
48     
49 
50 }