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

 1 package cn.yzu;
 2 import java.io.IOException;
 3 import javax.servlet.ServletException;
 4 import javax.servlet.http.HttpServlet;
 5 import javax.servlet.http.HttpServletRequest;
 6 import javax.servlet.http.HttpServletResponse;
 7 public class AServlet extends HttpServlet {
 8
 9     public void doGet(HttpServletRequest request, HttpServletResponse response)
10             throws ServletException, IOException {
11         System.out.println("AServlet被访问到。。。。。。。。。");
12         //重定向请求头,可用一个response.sendRedirect("BServlet")代替;
13         response.setStatus(302);
14         response.setHeader("Location", "BServlet");
15
16         //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
17         response.setHeader("pragma", "no-cache");
18         response.setHeader("cache-control", "no-cache");
19         response.setDateHeader("expires", -1);
20     }
21 }

BServlet

 1 package cn.yzu;
 2
 3 import java.io.IOException;
 4
 5 import javax.servlet.ServletException;
 6 import javax.servlet.http.HttpServlet;
 7 import javax.servlet.http.HttpServletRequest;
 8 import javax.servlet.http.HttpServletResponse;
 9
10 public class BServlet extends HttpServlet {
11     public void doGet(HttpServletRequest request, HttpServletResponse response)
12             throws ServletException, IOException {
13         System.out.println("BServlet被访问到。。。。。。。。。");
14         System.out.println("3秒钟后自动跳转到CServlet");
15         //自动刷新请求头
16         response.setHeader("Refresh", "3;URL=CServlet");
17     }
18 }

CServlet

 1 package cn.yzu;
 2
 3 import java.io.FileInputStream;
 4 import java.io.IOException;
 5
 6 import javax.servlet.ServletException;
 7 import javax.servlet.http.HttpServlet;
 8 import javax.servlet.http.HttpServletRequest;
 9 import javax.servlet.http.HttpServletResponse;
10
11 import org.apache.commons.io.IOUtils;
12
13 public class CServlet extends HttpServlet {
14     public void doGet(HttpServletRequest request, HttpServletResponse response)
15             throws ServletException, IOException {
16         System.out.println("CServlet被访问到。。。。。。。。。");
17         //response响应字节流（万能的，也可以输出字符）
18         FileInputStream stream=new FileInputStream("C:/Users/Administrator/Desktop/UI/头像/Lebron.jpeg");
19         //IO小工具，Apache提供，将输入流转换成字节数组
20         byte bt[]=IOUtils.toByteArray(stream);
21         //注：绝对不可以和response.getWriter()同时使用，否则会抛IllegalStateException异常！！！！！！！
22         response.getOutputStream().write(bt);
23
24     }
25
26 }

运行结果：

注：IO小工具jar包：