Servlet 3.0 does not need to be configured with web. xml, and uses the injection method to configure servlet for login (the server must support servlet3.0), web. xmlservlet3.0

Servlet 3.0 does not need to be configured with web. xml, and uses the injection method to configure servlet for login (the server must support servlet3.0), web. xmlservlet3.0

First, declare the above error, and I don't know what's going on.

Select java EE6.0 when creating a project, and no servlet3.0.

Let's take a look at a basic example.

Test. java is used to Test non-configuration files and no static pages (jsp, html)

Directly access the servlet to obtain information from the server.

Test. java code

1 package com. gys; 2 3 import java. io. IOException; 4 import java. io. printWriter; 5 6 import javax. servlet. servletException; 7 import javax. servlet. annotation. webServlet; 8 import javax. servlet. http. httpServlet; 9 import javax. servlet. http. httpServletRequest; 10 import javax. servlet. http. httpServletResponse; 11 12 @ WebServlet (13 name = "Test", 14 urlPatterns = {"/test"} 15) 16 17 public class Test extends HttpServlet {18 @ Override19 protected void doPost (HttpServletRequest req, HttpServletResponse resp) 20 throws ServletException, IOException {21 doGet (req, resp ); 22} 23 24 @ Override25 protected void doGet (HttpServletRequest request, HttpServletResponse response) 26 throws ServletException, IOException {27 response. setContentType ("text/html; charset = UTF-8"); 28 PrintWriter out = response. getWriter (); 29 out. println ("
Access results:

Read the above name and urlpattern parameters, and continue to look down.
ServletConfigDemo. java code
1 package com. gys; 2 3 import java. io. IOException; 4 import java. util. enumeration; 5 6 import javax. servlet. requestDispatcher; 7 import javax. servlet. servletConfig; 8 import javax. servlet. servletContext; 9 import javax. servlet. servletException; 10 import javax. servlet. annotation. webInitParam; 11 import javax. servlet. annotation. webServlet; 12 import javax. servlet. http. httpServlet; 13 import javax. servle T. http. httpServletRequest; 14 import javax. servlet. http. httpServletResponse; 15 import javax. servlet. http. httpSession; 16 17 @ WebServlet (18 urlPatterns = {"/servletConfigDemo. do "}, 19 loadOnStartup = 1,20 name =" servletConfigDemo ", 21 displayName =" demo ", 22 initParams = {23 @ WebInitParam (name =" success ", value = "success.html"), 24 @ WebInitParam (name = "error", value = "error.html") 25} 26) 27 public class servletConfigD Emo extends HttpServlet {28 @ Override29 protected void doPost (HttpServletRequest request, HttpServletResponse response) 30 throws ServletException, IOException {31 ServletConfig config = getletservconfig (); 32 // 1. getInitParameter (name) Method 33 String success = config. getInitParameter ("success"); 34 String error = config. getInitParameter ("error"); 35 36 System. out. println ("success -----" + success); 37 System. out. pr Intln ("errror ------" + error); 38 39 // 2. getInitParameterNames Method 40 Enumeration enumeration = config. getInitParameterNames (); 41 while (enumeration. hasMoreElements () {42 String name = (String) enumeration. nextElement (); 43 String value = config. getInitParameter (name); 44 System. out. println ("name -----" + name); 45 System. out. println ("value -----" + value); 46} 47 48 // 3getServletContext method 49 ServletContext servletContext = Config. getServletContext (); 50 System. out. println ("servletContext ----" + servletContext); 51 52 // 4. getServletName method 53 String servletName = config. getServletName (); 54 System. out. println ("servletName ------" + servletName); 55 56 request. setCharacterEncoding ("UTF-8"); 57 String userId = request. getParameter ("userId"); 58 String passwd = request. getParameter ("passwd"); 59 60 // judge 61 if (userId! = Null & "gys". equals (userId) & passwd! = Null & "gys ". equals (passwd) {62 HttpSession session = request. getSession (); 63 session. setAttribute ("user", userId); 64 // jump to 65 RequestDispatcher requestDispatcher = request. getRequestDispatcher (success); 66 requestDispatcher. forward (request, response); 67} 68 else {69 // jump to 70 RequestDispatcher requestDispatcher = request. getRequestDispatcher (error); 71 requestDispatcher. forward (request, response); 72} 73 74} 75}
Index. jsp
1 <% @ page language = "java" import = "java. util. * "contentType =" text/html; charset = UTF-8 "%> 2 <% 3 String path = request. getContextPath (); 4 String basePath = request. getScheme () + ": //" + request. getServerName () + ":" + request. getServerPort () + path + "/"; 5%> 6 7 <! Doctype html public "-// W3C // dtd html 4.01 Transitional // EN"> 8 
Implemented the login function