servlet 3.0无需配置web.xml,使用注入方式配置servlet实现登陆功能(服务器需要支持servlet3.0)

首先申明上面的报错红叉,我也不知道怎么回事.总之能运行.

新建项目时选择java EE6.0,低版本没有servlet3.0.

先看一个基本示例.

Test.java是用来测试无需配置文件,无需静态页面(jsp,html)

直接访问servlet来从服务器上获取信息.

Test.java代码

 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     @Override
19     protected void doPost(HttpServletRequest req, HttpServletResponse resp)
20             throws ServletException, IOException {
21         doGet(req, resp);
22     }
23
24     @Override
25     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("<h1>思思博士</h1>");
30     }
31 }

访问结果:

看懂上面的name和urlpattern参数的,继续往下看.

servletConfigDemo.java代码

 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.servlet.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 servletConfigDemo extends HttpServlet{
28     @Override
29     protected void doPost(HttpServletRequest request, HttpServletResponse response)
30             throws ServletException, IOException {
31         ServletConfig config=getServletConfig();
32         //1.getInitParameter(name)方法
33         String success=config.getInitParameter("success");
34         String error=config.getInitParameter("error");
35
36         System.out.println("success-----"+success);
37         System.out.println("errror------"+error);
38
39         //2.getInitParameterNames方法
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方法
49         ServletContext servletContext=config.getServletContext();
50         System.out.println("servletContext----"+servletContext);
51
52         //4.getServletName方法
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         //判断
61         if(userId!=null&&"gys".equals(userId)&&passwd!=null&&"gys".equals(passwd)){
62             HttpSession session=request.getSession();
63             session.setAttribute("user", userId);
64             //跳转
65             RequestDispatcher requestDispatcher=request.getRequestDispatcher(success);
66             requestDispatcher.forward(request, response);
67         }
68         else {
69             //跳转
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 <html>
 9   <head>
10     <base href="<%=basePath%>">
11
12     <title>登陆</title>
13     <meta http-equiv="pragma" content="no-cache">
14     <meta http-equiv="cache-control" content="no-cache">
15     <meta http-equiv="expires" content="0">
16     <meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
17     <meta http-equiv="description" content="This is my page">
18     <!--
19     <link rel="stylesheet" type="text/css" href="styles.css">
20     -->
21   </head>
22
23   <body>
24   <form action="servletConfigDemo.do" method="post">
25        用户名<input type="text" value="" name="userId" /><br/>
26        密码:<input type="password" name="passwd" />
27        <input type="submit" value="提交" />
28   </form>
29
30   </body>
31 </html>

实现登陆功能了