JSP

最新推荐文章于 2022-04-27 08:26:28 发布

P_ning

最新推荐文章于 2022-04-27 08:26:28 发布

阅读量266

点赞数

分类专栏： JavaWEB

本文链接：https://blog.youkuaiyun.com/P_ning/article/details/103042020

版权

JavaWEB 专栏收录该内容

10 篇文章

订阅专栏

源码自取:https://gitee.com/P_n_ing/JSP.git

内容

归根结地还是6大内置对象,链接里面有个jsp.docx文档,这个才是重点,下面不过是简单的样例而已

JSP的三种标签
JSP实现登陆和注册的页面跳转和数据提交
cookie的怎么来的
用cookie自动记住用户名

5. JSP通过Session实现登陆

<%@ 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=UTF-8">
<title>Insert title here</title>
</head>
<body>
	<form action="check.jsp" method="post">
		用户名:<input type="text" name="username"> 
		密码:<input type="password" name="userpassword">
		<input type="submit" value="登陆">
	</form>
</body>
</html>

check.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=UTF-8">
<title>Insert title here</title>
</head>
<body>
	<%
		request.setCharacterEncoding("utf-8");
		String name = request.getParameter("username");
		String password = request.getParameter("userpassword");
		if(name.equals("123") && password.equals("123")){
			session.setAttribute("username", name);
			session.setAttribute("userpassword", password);
//用于验证sessionid和JESSIONID是否一样			
			System.out.println("session		"+session.getId());
			Cookie c = new Cookie("username",name);
			response.addCookie(c);
			request.getRequestDispatcher("welcom.jsp").forward(request, response);
		}else{
			response.sendRedirect("login.jsp");
		}
	%>
</body>
</html>

lost.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=UTF-8">
<title>Insert title here</title>
</head>
<body>
		<%
			session.invalidate();//这个会将整个session都失效,一般用这个
			//session.removeAttribute("username");//让session的个别属性失效
			
		%>
</body>
</html>

test.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=UTF-8">
<title>Insert title here</title>
</head>
<body>
	<!--
	在同一次会话中,服务器内的文件是否都能拿到该session对象
	这也是为什么我们在一个浏览器里面登陆京东后,无论打开多少个京东的其他网页都会保持登录状态
	但注意的时不同浏览器之间因为JSESSIONID不同,所以你在谷歌登陆京东,但是你的ie仍然时未登录状态
	-->
	<%
		out.print(session.getAttribute("username"));
	//测试JSESSIONID与sessionid是否一致
		Cookie[] c = request.getCookies();
		for(Cookie cookies:c){
			if(cookies.getName().equals("JSESSIONID")){
				System.out.println("JESSION		"+cookies.getValue());
			}
		}
	%>
</body>
</html>

welcome.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=UTF-8">
<title>Insert title here</title>
</head>
<body>
		欢迎你
		<%
			String name = (String)session.getAttribute("username");
		//如果用toString()方法,那当对象为空时,则无法执行toString()方法而报错
			if(name != null){
				out.print(name);
				//session.setMaxInactiveInterval(60*10);
		%>
		<a href="lost.jsp">让sessionid失效</a>
		<% 
			}else{
				response.sendRedirect("login.jsp");
			}
		%>
</body>
</html>

在JSP中获得 Web 应用的路径