JSP实现数据保存
1、概述
2、使用session保存用户名
session工作方式：
会话的清除与过期：
createUser.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> <form id="" action="doCreateUser.jsp" method="post"> 用户名：<input type="text" name="userName"/> <input type="submit" value="提交"/> </form> <% // 取回提示信息 Object oMess = request.getAttribute("mess"); if (oMess != null) { out.print(oMess.toString()); } %> </body> </html> doCreateUser.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 userName = request.getParameter("userName"); //out.print(userName); if (userName.equals("admin")) { // 加入提示信息 request.setAttribute("mess","注册失败，更换用户名。"); request.getRequestDispatcher("createUser.jsp").forward(request, response); //response.sendRedirect("createUser.jsp"); } else { session.setAttribute("user",userName); //request.getRequestDispatcher("default.jsp").forward(request, response); response.sendRedirect("default.jsp"); } %> </body> </html> default.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.getAttribute("mess")).toString() %> --%> <% Object o = session.getAttribute("user"); if (o == null) { %> <form id="" action="doCreateUser.jsp" method="post"> 用户名：<input type="text" name="userName"/> <input type="submit" value="提交"/> </form> <% } else { out.print("欢迎你，" + o.toString()); %> <a href="doLoginOut.jsp">注销</a> <% } %> </body> </html> doLoginOut.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.removeAttribute("user");// 释放session //session.invalidate(); response.sendRedirect("default.jsp"); %> </body> </html> 3、使用cookie自动填写用户名
doCreateUser.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 userName = request.getParameter("userName"); //out.print(userName); if (userName.equals("admin")) { // 加入提示信息 request.setAttribute("mess","注册失败，更换用户名。"); request.getRequestDispatcher("createUser.jsp").forward(request, response); //response.sendRedirect("createUser.jsp"); } else { // 创建cookie Cookie cookie = new Cookie("user",userName); // 设置cookie的有效期,单位秒 cookie.setMaxAge(10); response.addCookie(cookie); session.setAttribute("user",userName); //request.getRequestDispatcher("default.jsp").forward(request, response); response.sendRedirect("default.jsp"); } %> </body> </html> default.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.getAttribute("mess")).toString() %> --%> <% // 获取cookie Cookie[] cookies = request.getCookies(); String user = ""; for (int i = 0 ; i < cookies.length ; i++) { if (cookies[i].getName().equals("user")) { user = cookies[i].getValue(); } } Object o = session.getAttribute("user"); if (o == null) { %> <form id="" action="doCreateUser.jsp" method="post"> 用户名：<input type="text" name="userName" value="<%=user%>"/> <input type="submit" value="提交"/> </form> <% } else { out.print("欢迎你，" + o.toString()); %> <a href="doLoginOut.jsp">注销</a> <% } %> </body> </html> 查看cookie文件：
cookie文件中的内容：
user
qwe
localhost/news/jsp/
1024
1578087680
30438420
1482467680
30438420
*
4、application实现计数器
<%@ 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.getAttribute("mess")).toString() %> --%> <% // 获取cookie Cookie[] cookies = request.getCookies(); String user = ""; for (int i = 0 ; i < cookies.length ; i++) { if (cookies[i].getName().equals("user")) { user = cookies[i].getValue(); } } Object o = session.getAttribute("user"); if (o == null) { %> <form id="" action="doCreateUser.jsp" method="post"> 用户名：<input type="text" name="userName" value="<%=user%>"/> <input type="submit" value="提交"/> </form> <% } else { out.print("欢迎你，" + o.toString()); %> <a href="doLoginOut.jsp">注销</a> <% } %> <% Object count = application.getAttribute("count"); if (count == null) { // 第一次访问 application.setAttribute("count", new Integer(1)); } else { Integer i = (Integer)count; // 每一次访问+1 application.setAttribute("count", i.intValue() + 1); } Integer icount = (Integer)application.getAttribute("count"); out.print("页面被访问了" + icount.intValue() + "次"); %> </body> </html> 5、三个对象的对比
6、jsp页面的组成部分
7、常用内置对象
8、数据保存
9、客户端请求新页面
注：修改onclick="return fun();"
10、处理中文乱码
来自：http://my.oschina.net/u/2320342/blog/398660
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