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