Servlet请求头response应用简单案例

Servlet请求头response应用简单案例：访问AServlet重定向到BServlet，5秒后跳到CServlet,并显示图片：

AServlet

 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);
     }
 }

BServlet

 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");
     }
 }

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);

     }

 }

运行结果：

注：IO小工具jar包：