利用http的referer头和Servlet隐藏JavaScript代码

1.       定义一个用于输出JavaScript代码 的Servlet类。
package com.mycompany.response.servlet;
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class HideJavaScript extends HttpServlet {
protected void service(HttpServletRequest request,
                    HttpServletResponse response) throws ServletException, IOException {
 
           response.setHeader("Pragma", "No-cache");
           response.setHeader("Cache-Control", "no-cache");
           response.setDateHeader("Expires", 0);
           response.setContentType("text/javascript;charset=UTF-8");
           PrintWriter out = response.getWriter();
           String referer = request.getHeader("referer");
           if(!(referer==null)&&!referer.equalsIgnoreCase("")&&referer.startsWith("http://localhost:8080/response/"))
           {
                    out.println("document.write('这些就是隐藏的JavaScript代码!')");
                    out.println("window.alert('执行了此代码!')");
           }
       &n