sevlet实现反盗链

package com.servlet;

import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

@WebServlet("/ss.do")
public class SecurityChainServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;

    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        // 模拟网站的资源
        String resouces = "this is a nice picture!";
        String referer = request.getHeader("referer");
        // 这里是网站的主机
        String netAddress = "http://localhost";
        if (referer == null || !referer.startsWith(netAddress)) {
            response.sendRedirect("/JavaWebDemo/index.jsp");
            // 结束
            return;
        }
        // 如果是从我们自己的网站过来的正常访问
        response.getWriter().println(resouces);

    }

}