HttpServletResponse禁止浏览器缓存失败？不知道为啥.....

package cn.itcast.demo01;

import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.PrintWriter;

public class ServletsDemo extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        resp.setContentType("text/html;charset=utf-8");
        //明确的通知浏览器不要进行缓存
        resp.setHeader("pragma", "no-cache"); // HTTP1.1
        resp.setHeader("Cache-Control", "no-cache"); // HTTP1.0
        resp.setDateHeader("Expires", 0); // prevents catching at proxy server
        PrintWriter out = resp.getWriter();
        out.println("本次响应的随机数为："+Math.random());
        out.println("<form action='NotServlet'"+"method='POST'>"+
                "第一个参数：<input type='text' name='p1'><br>"+
                "第二个参数：<textarea name = 'p2'></textarea><br>"+
                "<input type='submit' value='提交'>"+"</form>");
//        String data = "中国";
//        resp.setContentType("text/html;charset=utf-8");
//        PrintWriter out = resp.getWriter();
//        out.println(data);

    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doGet(req,resp);
    }
}