Request and response objects

request

• type ：HttpServletRequest

• summary ：request Equivalent to the browser sending a request message to the server , Package to request object . The object is created by the server , And send it to the in the form of parameters service() In the method , Finally, it was introduced into doGet() or doPost() In the method .

• effect ：

  1. Get request parameters
     Example ：
     Page code

<a href="EndServlet?uname=zs&pwd=123456">\</a>
<form action="EndServlet" method="post">
  	 user name ：<input id="username" type="text" name="username" value="" /><br>
  	 password ：<input id="pwd" type="password" name="password" value="123"/><br>
  	<input id="btnSub" type="submit" value=" Sign in " >
</form>

 - request.getParameter()： Get single request parameters 
 - request.getParameterValues()： Get multiple request parameters 

3. Get the information in the request header

   • request.getHeader(“User-Agent|Cookie|Referer”)

4. obtain URL Information 【http://localhost:8080/day06_servlet/】

   • Get agreement ：request.getScheme()
   • Get the server name ：request.getServerName()
   • Get server port :request.getServerPort()
   • Get context path 【 belt / Project name 】:request.getContextPath()

5. Forward the request 【 Path jump 】

   //1.  Get the transponder 
   RequestDispatcher requestDispatcher = request.getRequestDispatcher("login_success.html");
   //2.  Perform forwarding 
   requestDispatcher.forward(request,response);
   

6. Domain object 【 There are four ,ServletContext|request】

response

• type ：HttpServletResponse
• summary ：response It is equivalent to the response message from the server to the browser , Package to response object . The object is created by the server , And send it to the in the form of parameters service() In the method , Finally, it was introduced into doGet() or doPost() In the method .
• effect ：
  1. Get response flow , The response data
     • PrintWriter writer = response.getWriter();
     • writer.writer();|writer.print()
  2. Set the response header
     • response.setHeader(“Content-Type”,“text/html;charset=UTF-8”);
  3. Redirect 【 Path jump 】
     • response.sendRedirect(“url”);