The blogger's name is taken from 《 Shaun the Sheep 》 Shawn the lamb in the , The name is ： Sean , Transliterated as Sean, Take your own last name ： Archie , In order to conform to our reading habits , Connected to form ArchieSean. The blogger is currently a junior reading , Aiming to build blog into a technical stack of personal online notes , Be convenient for yourself and others . If there are any mistakes in the blog , Please point out , Thank you. .

Request and Response

principle

• request and response Are objects provided by the server .
• request Is used to get the request message
• response Is used to set the response message .

Request

Request Architecture of

Another class is provided by the server , It has achieved HttpServletRequest Interface .

Request The function of

More commonly used are ：

• A common way to get request parameters

request.getParameter(String name);	
request. getParameterValues(String name);
request.getParameterNames();
request. getParameterMap();

• solve POST Ask for Chinese code

request.setCharacterEncoding("utf-8");

• forward

request.getRequestDispatcher(String path).forward(request,response);

• Use of shared data

request.setAttribute（String key,Object obj）;
request.getAttribute（String key）;
request.removeAttribute(String key);

• obtain ServletContext object

  request.getServletContext();

Response

Response Architecture

Same as Request equally , Provides a server class , Realized HttpServletResponse Interface .

Response The function of

Commonly used ：

• Solve the problem of Chinese garbled code

 resp.setContentType("MIME type ; Character set ");

• Get stream object

1. Get character output stream
2. Get byte output stream

• Redirect

  resp.sendRedirect(String path);

ServletContext

summary

Simply speaking ,ServletContext yes web The largest domain object in the application . It means that all users under the same server can share data .

obtain

There are two ways to get this object ：

1. adopt request To get

request.getServletContext();

2. adopt servlet To get

this.getServletContext();

function

• Data sharing （ Three general methods of domain objects ）
• obtain MIME type

getMimeType（String file);

• Get resource path

  getRealPath(String path);

If there are any questions in the blog , Please leave a message .