How to use Java Web HttpServletResponse object

(1) Concept

There will be HttpServletRequest and HttpServletResponse objects in the parameters of doGet, doPost, and service methods.
HttpServletRequest represents an http request, which is used when you want to obtain the data in the request;
HttpServletResponse represents an http response, which is used when there is data that needs to be sent to the browser.

(2) Common methods

1)setHeader(String name, String value)

Set response header:
①Set text format and encoding
② Scheduled refresh
Scheduled refresh is set as the response header through Refresh, which can realize the jump url after a certain amount of time

//另外一种写法，使用setHeader方法
		response.setHeader("Content-Type", "text/html;charset=utf-8");

//获得字符输出流
		PrintWriter pw=response.getWriter();
		pw.write("5秒后进入百度");
		
		//设置定时刷新   --多少时间后进行跳转
		response.setHeader("Refresh","5;url=http://www.baidu.com");
		//间隔多少时间进行自刷新
		response.setHeader("Refresh", "5");
		//使用request作为域对象，存储数据
		request.setAttribute("name","zhangsan");

2) getWriter() --> PrintWriter

 getOutputStream()  -->ServletOuputStream
   		//输出信息到浏览器端

//获得字节流，将数据写到浏览器端
	    ServletOutputStream sos=response.getOutputStream();
		sos.write("200".getBytes());
		sos.write("\n".getBytes());
		byte[] bs="world".getBytes();
		sos.write(bs);
		sos.write("<br/>".getBytes());
		sos.write("中国".getBytes("utf-8"));

3) setContentType()

Set the Chinese encoding and text format of the response to the browser

//设置显示到浏览器端的文本格式和编码
response.setContentType("text/html;charset=utf-8");

4) Redirect

sendRedirect(“xxxx”)//xxx represents the redirected address
①It is used to jump to internal resources on the server side, and can also be used to jump between different applications and different servers
②The redirected browser address bar will generate variables, and the browser address bar will be the address after redirection
③Redirect is equivalent to 2 requests, 2 responses
④Redirect is generally used for things that have already happened Done, just to jump to the next component.

//重定向
		//一般是事情已经完成了，只是为了下一个组件的跳转，浏览器地址栏的地址会发生变化
		//重定向是两次请求，request作用域中存储的数据不能实现共享
		//重定向是通过HttpServletResponse对象调出的
	    response.sendRedirect("index.jsp");
		//response.sendRedirect("register.html");

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