Web项目-HttpSession

HttpSession是由JavaWeb提供的，用来会话跟踪的类。session是服务器端的对象，保存在服务器端

服务器会为每个客户端创建一个session对象，session就好比客户端在服务器端的账号，他们被服务器保存在一个map中，这个map称之为session缓存

Servlet中得到session对象：

HttpSession session = request.getSession();

JSP中session是内置对象之下，不用创建就可以直接使用

案例1：演示session中会话的多次请求中共享数据

a.jsp:<% session.setAttritube("aaa","AAA");%>

b.jsp:<% String s = (String)session.getAttritube("aaa");%>

<%=s%>

案例2：演示保存用户登陆信息

succ1.jsp:登陆成功才能访问的页面

LoginServlet:校验用户是否登陆成功

<%@ page language="java" contentType="text/html; charset=utf-8"
    pageEncoding="utf-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>Insert title here</title>
</head>
<body>
<h1>登录</h1>
<%
	String message = "";
	String msg = (String)request.getAttribute("msg");
	if(msg != null){
		message = msg;
	}

%>
<font color="red"><b><%=message %></b></font>
	<form action="/JSPDemo/LoginServlet" method="post">
		用户名<input type="text" name="username"/><br>
		密码<input type="password" name="password"/><br>
		<input type="submit" value="登录"/>
	</form>
</body>
</html>

LoginServlet

package com.servlet;

import java.io.IOException;

import javax.servlet.ServletException;
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;

/**
 * Servlet implementation class LoginServlet
 */
@WebServlet("/LoginServlet")
public class LoginServlet extends HttpServlet {
	private static final long serialVersionUID = 1L;

	/**
	 * @see HttpServlet#HttpServlet()
	 */
	public LoginServlet() {
		super();
		// TODO Auto-generated constructor stub
	}

	/**
	 * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		// TODO Auto-generated method stub
		doPost(request, response);
	}

	/**
	 * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		request.setCharacterEncoding("utf-8");
		String username = request.getParameter("username");
		String password = request.getParameter("password");
		if ("sutu".equalsIgnoreCase(username)) {
			HttpSession session = request.getSession();
			session.setAttribute("username", username);
			response.sendRedirect("/JSPDemo/jsps/succ1.jsp");
		}else{
			request.setAttribute("msg", "用户名或密码错误");
			request.getRequestDispatcher("/jsps/login.jsp").forward(request, response);
		}
	}

}

succ1.jsp

<%@ page language="java" contentType="text/html; charset=utf-8"
    pageEncoding="utf-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>Insert title here</title>
</head>
<body>
<%
String username = (String)session.getAttribute("username");
if(username == null){
	request.setAttribute("msg", "还没有登陆");
	request.getRequestDispatcher("/jsps/login.jsp").forward(request, response);
	return;
}
%>
	<h1>登陆成功</h1>
	欢迎<%=username %>
</body>
</html>

猜你喜欢