黑马day05 session实现登陆&注销小案例

时间：2015-06-20 09:13:20 阅读：292 评论：0 收藏：0 [点我收藏+]

本案例主要使用session实现登录与注销的功能。

1.登录页面

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>


<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
  
    
    <title></title>
    
	<meta http-equiv=" pragma" content="no-cache">
	<meta http-equiv="cache-control" content="no-cache">
	<meta http-equiv="expires" content="0">    
	
  </head>
  
  <body>
    <form action="${pageContext.request.contextPath }/servlet/LoginServlet" method="post">
    	登陆名：<input type="text" name="username"/><br/>
    	密码：    <input type="password" name="password"/><br/>
    	<input type="submit" value="提交"/><br/>
    </form>
  </body>
</html>

运行界面：

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2.使用UserDao模拟数据库提供对外验证密码和密码是否正确的函数

package cn.itheima.loginout;

import java.util.HashMap;
import java.util.Map;

public class UserDao {
	private static Map<String, String> map=new HashMap<String, String>();
	static{
		map.put("李卫康", "123");
	}
	//提供验证用户名和密码的方法
	public static boolean validateUsernamePassword(String username,String password){
		return map.containsKey(username)&&map.get(username).equals(password);
		
	}
}

3.实现LoginServlet的代码,因为login.jsp是post的提交方式,这里为了方便我使用rrequest.setCharacterEncoding("utf-8");告诉服务器使用utf-8编码，这里向服务器输出了汉字，因此采用response.setContentType("text/html;charset=utf-8");来解决乱码问题....这句话两个作用...这里我就不介绍了、

package cn.itheima.loginout;

import java.io.IOException;

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

public class LoginServlet extends HttpServlet {

	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		request.setCharacterEncoding("utf-8");
		response.setContentType("text/html;charset=utf-8");
		//1.得到参数
		String username = request.getParameter("username");
		String password = request.getParameter("password");
		//2.从数据库中查询并判断
		if(UserDao.validateUsernamePassword(username, password)){
			request.getSession().setAttribute("user", username);
			//重定向到主页、
			response.sendRedirect(request.getContextPath()+"/loginout/index.jsp");
		}else{
			response.getWriter().write("对不起您没有登陆！三秒后跳转到登陆页面");
			response.setHeader("Refresh", "3;url=/day05/loginout/login.jsp");
		}
		
	}

	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		doGet(request, response);
	}

}

4.index.jsp如果没有登陆就欢迎光临游客！如果从session中查出用户就欢迎指定的用户

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>


<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
  
    
    <title></title>
    
	<meta http-equiv=" pragma" content="no-cache">
	<meta http-equiv="cache-control" content="no-cache">
	<meta http-equiv="expires" content="0">    
	
  </head>
  
  <body>
    <%
    String user=(String)session.getAttribute("user");
     %>
     <%
     if(user==null||"".equals(user)){
     %>
     	欢迎观临！游客！
     	<a href="${pageContext.request.contextPath }/loginout/login.jsp">登录</a>
     <%
     	}else{	
      %>
      	欢迎回来！<%=user %>
      	<a href="${pageContext.request.contextPath }/servlet/LogoutServlet">注销</a>
      <%
      	}
       %>
     
  </body>
</html>

运行界面：

未登录：

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