filter防盗链

1这次练习中一直受到相对路径的干扰，现在澄清一点

forward中不是不需要包含根目录的比如 http://localhost:8080/filter/upload/images/no.jpg

你只要写到 (/upload/images/no.jpg)就好

而在html中是需要根目录的

<img src="<%=request.getContextPath()%>/images/ok.jpg" /></div> 
    
    <a href="<%=request.getContextPath()%>/d.jpg">直接访问d</a>
    <a href="<%=request.getContextPath()%>/images/ok.jpg">直接访问ok</a>
    <a href="<%=request.getContextPath()%>/upload/images/no.jpg">直接访问no</a>

2根据referer判断是否自己网站发出的请求

        String referer = req.getHeader("referer");
        if (referer == null || !referer.contains(req.getServerName())) {

源码

package filter;

import java.io.IOException;

import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class MyFilter implements Filter {

    @Override
    public void destroy() {
        // TODO Auto-generated method stub
    }

    @Override
    public void doFilter(ServletRequest request, ServletResponse response,
            FilterChain chain) throws IOException, ServletException {
        // TODO Auto-generated method stub
        HttpServletRequest req = (HttpServletRequest) request;// 注意上面是接口servletRequest/response
        HttpServletResponse res = (HttpServletResponse) response;

        String referer = req.getHeader("referer");
        if (referer == null || !referer.contains(req.getServerName())) {
            req.getRequestDispatcher("/d.jpg").forward(req, res);
        } else {
            chain.doFilter(request, response);
        }

    }

    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
        // TODO Auto-generated method stub
    }

}

View Code

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <base href="<%=basePath%>">
    
    <title>My JSP 'show.jsp' starting page</title>
    
    <meta http-equiv="pragma" content="no-cache">
    <meta http-equiv="cache-control" content="no-cache">
    <meta http-equiv="expires" content="0">    
    <meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
    <meta http-equiv="description" content="This is my page">
    <!--
    <link rel="stylesheet" type="text/css" href="styles.css">
    -->
    <%
        
        
        
     %>

  </head>
  
  <body>
     <p>dsf</p>
    <div class="zj02"><img src="<%=request.getContextPath()%>/images/ok.jpg" /></div> 
    
    <a href="<%=request.getContextPath()%>/d.jpg">直接访问d</a>
    <a href="<%=request.getContextPath()%>/images/ok.jpg">直接访问ok</a>
    <a href="<%=request.getContextPath()%>/upload/images/no.jpg">直接访问no</a>
                                            
  </body>
</html>

View Code

模拟直接访问

<!DOCTYPE html>
<html>
    <head>
        <meta charset="UTF-8">
        <title></title>
    </head>
    <body>
            <a href="http://localhost:8080/filter/d.jpg">直接访问d</a>
            <a href="http://localhost:8080/filter/images/ok.jpg">直接访问ok</a>
                <a href="http://localhost:8080/filter/upload/images/no.jpg">直接访问no</a>
    </body>
</html>

View Code

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原文地址：https://www.cnblogs.com/vhyc/p/6479817.html