package cn.yzu;

 import java.io.IOException;

 import javax.servlet.ServletException;

 import javax.servlet.http.HttpServlet;

 import javax.servlet.http.HttpServletRequest;

 import javax.servlet.http.HttpServletResponse;

 public class AServlet extends HttpServlet {

     public void doGet(HttpServletRequest request, HttpServletResponse response)

             throws ServletException, IOException {

         System.out.println("AServlet被访问到。。。。。。。。。");

         //重定向请求头,可用一个response.sendRedirect("BServlet")代替;

         response.setStatus(302);

         response.setHeader("Location", "BServlet");

         //取消缓存请求头，3个组合适用于所有浏览器，可用<meta>标签代替

         response.setHeader("pragma", "no-cache");

         response.setHeader("cache-control", "no-cache");

         response.setDateHeader("expires", -1);

     }

 }

 package cn.yzu;

 import java.io.IOException;

 import javax.servlet.ServletException;

 import javax.servlet.http.HttpServlet;

 import javax.servlet.http.HttpServletRequest;

 import javax.servlet.http.HttpServletResponse;

 public class BServlet extends HttpServlet {

     public void doGet(HttpServletRequest request, HttpServletResponse response)

             throws ServletException, IOException {

         System.out.println("BServlet被访问到。。。。。。。。。");

         System.out.println("3秒钟后自动跳转到CServlet");

         //自动刷新请求头

         response.setHeader("Refresh", "3;URL=CServlet");

     }

 }

 package cn.yzu;

 import java.io.FileInputStream;

 import java.io.IOException;

 import javax.servlet.ServletException;

 import javax.servlet.http.HttpServlet;

 import javax.servlet.http.HttpServletRequest;

 import javax.servlet.http.HttpServletResponse;

 import org.apache.commons.io.IOUtils;

 public class CServlet extends HttpServlet {

     public void doGet(HttpServletRequest request, HttpServletResponse response)

             throws ServletException, IOException {

         System.out.println("CServlet被访问到。。。。。。。。。");

         //response响应字节流（万能的，也可以输出字符）

         FileInputStream stream=new FileInputStream("C:/Users/Administrator/Desktop/UI/头像/Lebron.jpeg");

         //IO小工具，Apache提供，将输入流转换成字节数组

         byte bt[]=IOUtils.toByteArray(stream);

         //注：绝对不可以和response.getWriter()同时使用，否则会抛IllegalStateException异常！！！！！！！

         response.getOutputStream().write(bt);

     }

 }