Java HttpServletResponse响应 Java HttpServletResponse响应实现过程详解
嘿抬头i 人气:0用户在客户端输入网址(虚拟路径)时,开始发送一个HTTP请求(请求行、请求头、请求体)至服务器。服务器内的Tomcat引擎会解析请求的地址,去找XML文件,然后根据虚拟路径找Servlet的真实路径,真实的Servlet会将请求的信息封装成request(请求)对象,然后再创建一个response(响应)对象,(此时的response内是空的)同时创建servlet对象,并调用service方法(或doGet和doPost方法)。
这样就是把两个对象传给了服务器内的某个servlet的service方法,通过这个方法,我们可以获得request的所有的信息,并且向response内设置信息。response.getwriter().write()将内容写到response的缓冲区,这样service方法结束了,方法返回后,tomcat引擎会将从该response缓冲区中获取的设置信息封装成一个HTTP响应(响应行、响应头、响应体),发送给客户端。客户端解析响应回来的东西继而进行显示。
概述:
我们在创建Servlet时会覆盖service()方法,或doGet()/doPost(),这些方法都有两个参数,一个为代表请求的request和代表响应response。service方法中的response的类型是ServletResponse,而doGet/doPost方法的response的类型是HttpServletResponse,HttpServletResponse是ServletResponse的子接口,功能和方法更加强大
通过response 设置响应行:
设置响应行的状态码:setStatus( int sc)
通过response 设置响应头:
setHeader(String name,String value) 设置
三秒以后跳转到百度:
public class RefreshServlet extends HttpServlet { protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { //设置定时刷新的头 response.setHeader("refresh","5;url=https://www.baidu.com"); } protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doGet(request, response); } }
<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%> <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> <title>Insert title here</title> <script type="text/javascript"> window.onload=function(){ //获取span元素 var second=document.getElementById("second"); //定义秒数 var time =5; //设置定时器 var timer=setInterval(function(){ second.innerHTML=time; time--; if(time < 0){ clearInterval(timer); location.href="https://www.baidu.com" rel="external nofollow" rel="external nofollow" ; } },1000); } </script> </head> <body> 恭喜您,注册成功! <span id="second" style="color:red">5</span> 秒后跳转,如没跳转,请点击<a href="https://www.baidu.com" rel="external nofollow" rel="external nofollow" >这里</a> </body> </html>
重定向:(请求服务器两次,地址栏变化)
①、状态码:302;
②、响应头:location 代表重定向地址;
public class Servlet01 extends HttpServlet { private static final long serialVersionUID = 1L; protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { /*// 设置响应状态码 response.setStatus(302); //设置响应头中的Location response.setHeader("Location","/WEB0/Servlet02");*/ //重定向 response.sendRedirect("/WEB0/Servlet02"); } protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doGet(request, response); } }
public class Servlet02 extends HttpServlet { protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { response.getWriter().write("Servlet02"); } protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doGet(request, response); } }
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