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

 package com.gys;

 import java.io.IOException;
 import java.io.PrintWriter;

 import javax.servlet.ServletException;
 import javax.servlet.annotation.WebServlet;
 import javax.servlet.http.HttpServlet;
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;

 @WebServlet(
             name="Test",
             urlPatterns={"/test"}
         )

 public class Test extends HttpServlet{
     @Override
     protected void doPost(HttpServletRequest req, HttpServletResponse resp)
             throws ServletException, IOException {
         doGet(req, resp);
     }

     @Override
     protected void doGet(HttpServletRequest request, HttpServletResponse response)
             throws ServletException, IOException {
         response.setContentType("text/html;charset=utf-8");
         PrintWriter out=response.getWriter();
         out.println("<h1>思思博士</h1>");
     }
 }

访问结果:

看懂上面的name和urlpattern参数的,继续往下看.

servletConfigDemo.java代码

 package com.gys;

 import java.io.IOException;
 import java.util.Enumeration;

 import javax.servlet.RequestDispatcher;
 import javax.servlet.ServletConfig;
 import javax.servlet.ServletContext;
 import javax.servlet.ServletException;
 import javax.servlet.annotation.WebInitParam;
 import javax.servlet.annotation.WebServlet;
 import javax.servlet.http.HttpServlet;
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;
 import javax.servlet.http.HttpSession;

 @WebServlet(
         urlPatterns={"/servletConfigDemo.do"},
         loadOnStartup=1,
         name="servletConfigDemo",
         displayName="demo",
         initParams={
                 @WebInitParam(name="success",value="success.html"),
                 @WebInitParam(name="error",value="error.html")
         }
     )
 public class servletConfigDemo extends HttpServlet{
     @Override
     protected void doPost(HttpServletRequest request, HttpServletResponse response)
             throws ServletException, IOException {
         ServletConfig config=getServletConfig();
         //1.getInitParameter(name)方法
         String success=config.getInitParameter("success");
         String error=config.getInitParameter("error");

         System.out.println("success-----"+success);
         System.out.println("errror------"+error);

         //2.getInitParameterNames方法
         Enumeration enumeration=config.getInitParameterNames();
         while(enumeration.hasMoreElements()){
             String name=(String)enumeration.nextElement();
             String value=config.getInitParameter(name);
             System.out.println("name-----"+name);
             System.out.println("value-----"+value);
         }

         //3getServletContext方法
         ServletContext servletContext=config.getServletContext();
         System.out.println("servletContext----"+servletContext);

         //4.getServletName方法
         String servletName=config.getServletName();
         System.out.println("servletName------"+servletName);

         request.setCharacterEncoding("UTF-8");
         String userId=request.getParameter("userId");
         String passwd=request.getParameter("passwd");

         //判断
         if(userId!=null&&"gys".equals(userId)&&passwd!=null&&"gys".equals(passwd)){
             HttpSession session=request.getSession();
             session.setAttribute("user", userId);
             //跳转
             RequestDispatcher requestDispatcher=request.getRequestDispatcher(success);
             requestDispatcher.forward(request, response);
         }
         else {
             //跳转
             RequestDispatcher requestDispatcher=request.getRequestDispatcher(error);
             requestDispatcher.forward(request, response);
         }

     }
 }

index.jsp

 <%@ page language="java" import="java.util.*" contentType="text/html; charset=utf-8"%>
 <%
 String path = request.getContextPath();
 String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
 %>

 <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
 <html>
   <head>
     <base href="<%=basePath%>">

     <title>登陆</title>
     <meta http-equiv="pragma" content="no-cache">
     <meta http-equiv="cache-control" content="no-cache">
     <meta http-equiv="expires" content="0">
     <meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
     <meta http-equiv="description" content="This is my page">
     <!--
     <link rel="stylesheet" type="text/css" href="styles.css">
     -->
   </head>

   <body>
   <form action="servletConfigDemo.do" method="post">
        用户名<input type="text" value="" name="userId" /><br/>
        密码:<input type="password" name="passwd" />
        <input type="submit" value="提交" />
   </form>

   </body>
 </html>

实现登陆功能了