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：