jsp2


JSP内置对象
1：内置对象简介
  JSP内置对象是WEB容器创建的一组对象，不是用new 关键就可以使用的
2：四种作用域范围
3：out
4:request/response
5:seession
6:applicaton
7:其他

    
JSP内置对象是WEB容器中创建的一组对象，可以直接使用不需要new，如截图中的out 对象



五大常用对象： out、request、response、session、application<br>
其它四个不常用对象：page、pageContext、exception、config
  1. <%@ page language="java" import="java.util.*" contentType="text/html; charset=UTF-8"%>
  2. <%
  3. String path = request.getContextPath();
  4. String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
  5. %>
  7. <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
  8. <html>
  9.   <head>
  10.     <base href="<%=basePath%>">
  11.     
  12.     <title>My JSP 'MyJsp.jsp' starting page</title>
  13.     
  14. 	<meta http-equiv="pragma" content="no-cache">
  15. 	<meta http-equiv="cache-control" content="no-cache">
  16. 	<meta http-equiv="expires" content="0">    
  17. 	<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
  18. 	<meta http-equiv="description" content="This is my page">
  19. 	<!--
  20. 	<link rel="stylesheet" type="text/css" href="styles.css">
  21. 	-->
  23.   </head>
  24.   
  25.   <body>
  26.    
     <h1>out内置对象</h1>
        <%
        //clear()清除缓冲区
        out.println("<h2>静夜思</h2>");
        out.println("床前明月光<br>");
        out.println("床前明月光<br>");
        out.flush();//没任何区别输出，缓冲区变大，调用clear()的话，会打印前几句，false
        //clearBuffer() 不会抛出异常
        out.println("床前明月光<br>");
        out.println("床前明月光<br>");
        %>
        缓冲区大小:<%=out.getBufferSize() %>byte<br>
        缓冲区剩余大小：<%=out.getRemaining() %>byte<br>
      是否清空缓冲区：<%=out.isAutoFlush() %><br>
      </body>
  27. </html>

  1. <%@ page language="java" import="java.util.*"
  2. 	contentType="text/html; charset=UTF-8"%>
  3. <%
  4. 	String path = request.getContextPath();
  5. 	String basePath = request.getScheme() + "://"
  6. 			+ request.getServerName() + ":" + request.getServerPort()
  7. 			+ path + "/";
  8. %>
  10. <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
  11. <html>
  12. <head>
  13. <base href="<%=basePath%>">
  15. <title>My JSP 'login.jsp' starting page</title>
  17. <meta http-equiv="pragma" content="no-cache">
  18. <meta http-equiv="cache-control" content="no-cache">
  19. <meta http-equiv="expires" content="0">
  20. <meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
  21. <meta http-equiv="description" content="This is my page">
  22. <!--
  23. 	<link rel="stylesheet" type="text/css" href="styles.css">
  24. 	-->
  26. </head>
  28. <body>
  29. 	<h1>用户登录</h1>
  30. 	<hr> 
  31. 	<from action="dologin.jsp" name="loginForm" method="get"><%--post --%>
  32. 	<table>
  33. 		<tr>
  34. 			<td>用户名:</td>
  35. 			<td><input type="text" name="username"></td>
  36. 		</tr>
  37. 		<tr>
  38. 			<td>密码:</td>
  39. 			<td><input type="password" name="password"></td>
  40. 		</tr>
  41. 		<tr>
  42. 			<td colspan="2"><input type="submit" value="登陆"></td>
  43. 		</tr>
  44. 	</table>
  45. 	</from>
  46. </body>
  47. </html>

  1. <body>
  2.    <h1>登陆成功</h1>
  3.    <hr>
  4.   </body>


  1. <%@ page language="java" import="java.util.*"
  2. 	contentType="text/html; charset=UTF-8"%>
  3. <%
  4. 	String path = request.getContextPath();
  5. 	String basePath = request.getScheme() + "://"
  6. 			+ request.getServerName() + ":" + request.getServerPort()
  7. 			+ path + "/";
  8. %>
  10. <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
  11. <html>
  12. <head>
  13. <base href="<%=basePath%>">
  15. <title>My JSP 'req.jsp' starting page</title>
  17. <meta http-equiv="pragma" content="no-cache">
  18. <meta http-equiv="cache-control" content="no-cache">
  19. <meta http-equiv="expires" content="0">
  20. <meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
  21. <meta http-equiv="description" content="This is my page">
  22. <!--
  23. 	<link rel="stylesheet" type="text/css" href="styles.css">
  24. 	-->
  26. </head>
  28. <body>
  29. 	<h1>用户注册</h1>
  30. 	<hr>
  31. 	<form name="regForm" action="request.jsp" method="post">
  32. 		<table>
  33. 			<tr>
  34. 				<td>用户名:</td>
  35. 				<td><input type="text" name="username"></td>
  36. 			</tr>
  37. 			<tr>
  38. 				<td>爱好:</td>
  39. 				<td><input type="checkbox" name="favorite" value="read">读书
  40. 					<input type="checkbox" name="favorite" value="music">音乐 <input
  41. 					type="checkbox" name="favorite" value="movie">电影 <input
  42. 					type="checkbox" name="favorite" value="internet">上网</td>
  43. 			</tr>
  44. 			<tr>
  45. 				<td colspan="2"><input type="submit" value="登陆"></td>
  46. 			</tr>
  47. 		</table>
  48. 	</form>
  49. 	<br>
  50. 	<a href="request.jsp?username=lisi"> 测试url传参</a>  <!-- 中文“李四”会出问题，通过tomcat-conf-server-Connector标签+URLEncoding="utf-8"-重启tomcat -->
  51. </body>
  52. </html>
  1. <body>
  3. 	<h1>requst内置对象</h1>
  4. 	<%
  5. 		request.setCharacterEncoding("utf-8");//可以提交汉字
  6. 		request.setAttribute("password", "123456");
  7. 	%>
  8. 	用户名:<%=request.getParameter("username")%><br> 爱好：<%
  9. 		if (request.getParameterValues("favorite") != null) {
  10. 			String[] favorites = request.getParameterValues("favorite");
  11. 			for (int i = 0; i < favorites.length; i++) {
  12. 				out.println(favorites[i] + "&nbsp;");
  13. 			}
  14. 		}
  15. 	%><br> 密码：<%=request.getAttribute("password")%><br>
  16. 	请求体的MIME类型：<%=request.getContentType()%><br> 协议类型及版本号：<%=request.getProtocol()%><br>
  17. 	服务器主机名：<%=request.getServerName()%><br> 服务器端口号：<%=request.getServerPort()%><br>
  18. 	请求文件的长度（字节）：<%=request.getContentLength()%><br> 请求客户端的ip地址：<%=request.getRemoteAddr()%><br>
  19. 	请求真实路径 ：<%=request.getRealPath("request.jsp")%><br> 请求上下文路径：<%=request.getContextPath()%><br>
  20. </body>
response对象
-
  1. <%@page import="java.io.PrintWriter"%>
  2. <%@ page language="java" import="java.util.*"
  3. 	contentType="text/html; charset=UTF-8"%>
  4. <%
  5. 	response.setContentType("text/html; charset=UTF-8");//设置的响应的MIMI类型
  6. 	out.println("<h1>reponse内置对象</h1>");
  7. 	out.println("<br>tttt");
  8. 	PrintWriter out = response.getWriter();//获取输出流对象
  9. 	outer.println("大家好，我是response输出流");//输出 提前与内置out，用.fluse(清缓存)可以将out提前
  10. 	response.sendRedirect("reg.jsp");//请求重定向（直接跳转）
  1. %>
-请求重定向
  客户端行为-----response.sendRedirect(),两次请求，地址栏地址改变
-请求转发
  服务器行为-----request.getRequestDispatcher().forward(req,resp);地址不改变
  1. <body>
  2. 	<h1>用户注册</h1>
  3. 	<hr>
  4. 	<form name="regForm" action="response.jsp" method="post">
  5.           <-- action="response.jsp"-->
  6. 		<table>
  7. 			<tr>
  8. 				<td>用户名:</td>
  9. 				<td><input type="text" name="username"></td>
  10. 			</tr>
  11. 			<tr>
  12. 				<td>爱好:</td>
  13. 				<td><input type="checkbox" name="favorite" value="read">读书
  14. 					<input type="checkbox" name="favorite" value="music">音乐 <input
  15. 					type="checkbox" name="favorite" value="movie">电影 <input
  16. 					type="checkbox" name="favorite" value="internet">上网</td>
  17. 			</tr>
  18. 			<tr>
  19. 				<td colspan="2"><input type="submit" value="登陆"></td>
  20. 			</tr>
  21. 		</table>
  22. 	</form>
  23. 	<br>
  24. 	<a href="request.jsp?username=lisi"> 测试url传参</a>
  25. 	<!-- 中文“李四”会出问题，通过tomcat-conf-server-Connector标签+URLEncoding="utf-8"-重启tomcat -->
  26. </body>

  1. <%@page import="java.io.*,java.util.*"%>
  2. <%@ page language="java" import="java.util.*"
  3. 	contentType="text/html; charset=UTF-8"%>
  4. <%
  5. 	response.setContentType("text/html; charset=UTF-8");//设置的响应的MIMI类型
  6. 	out.println("<h1>reponse内置对象</h1>");
  7. 	out.println("<br>tttt");
  8. 	PrintWriter outer = response.getWriter();//获取输出流对象
  9. 	outer.println("大家好，我是response输出流");//输出 提前与内置out，用.fluse(清缓存)可以将out提前
  10. 	//response.sendRedirect("reg.jsp");//请求重定向（直接跳转）
  11. 	//请求重定向	response.sendRedirect("request.jsp");
  12. 	//请求转发
  13. 	request.getRequestDispatcher("request.jsp").forward(request, response);
  14. %>
session
 客户端和服务器一次对话----用户浏览网站花费的时间
  在服务器内存中保存着不同用户session
                 内置对象
  1. <body>
  3. 	<h1>session内置对象</h1>
  4. 	<hr>
  5. 	<%
  6. 	SimpleDateFormat sdf=new SimpleDateFormat("yyyy年MM月dd日  HH:mm:ss");
  7. 	Date d=new Date(session.getCreationTime());/* 时间化 */
  8. 	session.setAttribute("username", "admin");
  9. 	%>
  10. 	Session创建时间：<%=sdf.format(d) %><br><!-- 直接session.getCreationTime()会出现一长串代码 -->
  11. 	Session的ID编号：<%=session.getId() %><br>
  12. 	从Session获取用户名：<%=session.getAttribute("username") %><br>
  13. </body>
  1. <body>
  3. 	<h1>session内置对象1</h1>
  4. 	<hr>
  5. 	<%
  6. 	SimpleDateFormat sdf=new SimpleDateFormat("yyyy年MM月dd日  HH:mm:ss");
  7. 	Date d=new Date(session.getCreationTime());/* 时间化 */
  8. 	session.setAttribute("username", "admin");
  9. 	session.setAttribute("password", "123456");
  10. 	session.setAttribute("age", "18");
  11. 	//设置当前session最大生成期限单位是秒
  12. 	session.setMaxInactiveInterval(10);//10s
  13. 	%>
  14. 	Session创建时间：<%=sdf.format(d) %><br><!-- 直接session.getCreationTime()会出现一长串代码 -->
  15. 	Session的ID编号：<%=session.getId() %><br>
  16. 	从Session获取用户名：<%=session.getAttribute("username") %><br>
  17. 	<a href="session2.jsp" target="_blank">用超链接跳转到Session2</a>
  18. </body>
  1. <body>
  3. 	<h1>session内置对象2</h1>
  4. 	<hr>
  5. 	<%
  6. // 	SimpleDateFormat sdf=new SimpleDateFormat("yyyy年MM月dd日  HH:mm:ss");
  7. //  Date d=new Date(session.getCreationTime());/* 时间化 */
  8. //	session.setAttribute("username", "admin"); 
  9. 	%>
  10. 	Session的ID编号：<%=session.getId()%><br> 从Session获取用户名：<%=session.getAttribute("username")%><br>
  11. 	session中保存的全部属性：<%
  12. 		String[] names = session.getValueNames();
  13. 		for (int i = 0; i < names.length; i++) {
  14. 			out.println(names[i] + "&nbsp;");
  15. 		}
  16. 	%>
  17. </body>
session生命周期
创建-活动-销毁
  session对象
Tomcat默认超时30s
.设置Session超时两种方式
 1.session.setMaxInactiveInterval(时间)//单位是秒
2：在web.xml配置
 <session-confi> <session-timeout>10</session-timeout></session-confi>//单位分
application
实现用户间数据共享，可存放全局变量
开始与服务器启动，终止服务器关闭
  public void setAttribute(String,Object)使用指定名称将对象绑定到对话
public Object getAttribute(String)返回uzai次对话中指定名称绑定在一起的对象，没有返回null
Enumeration getAttributeNames()返回可用属性名枚举
String getServerInfo()返回JSP（SERVET）引擎名及版本号
  1. <%@ page language="java" import="java.util.*" contentType="text/html; charset=UTF-8"%>
  2. <%
  3. String path = request.getContextPath();
  4. String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
  5. %>
  7. <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
  8. <html>
  9.   <head>
  10.     <base href="<%=basePath%>">
  11.     
  12.     <title>My JSP 'application.jsp' starting page</title>
  13.     
  14. 	<meta http-equiv="pragma" content="no-cache">
  15. 	<meta http-equiv="cache-control" content="no-cache">
  16. 	<meta http-equiv="expires" content="0">    
  17. 	<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
  18. 	<meta http-equiv="description" content="This is my page">
  19. 	<!--
  20. 	<link rel="stylesheet" type="text/css" href="styles.css">
  21. 	-->
  23.   </head>
  24.   
  25.   <body>
  26.    <h1>application内置对象</h1>
  27. 	<hr>
  28. 	<%
  29. 	application.setAttribute("city", "北京");
  30. 	application.setAttribute("postcode", "10000");
  31. 	application.setAttribute("email", "lisi@126.com");
  32. 	%>
  33. 	所在城市：<%=application.getAttribute("city") %><br>
  34. 	application所有属性：<%
  35. 	Enumeration attibute=application.getAttributeNames();
  36. 	while(attibute.hasMoreElements()){
  37. 		out.println(attibute.nextElement()+"
");
  38. 	}
  39. 	%><br>
  40. 	JSp(SERVET)引擎名及版本号:<%=application.getServerInfo() %>
  41.   </body>
  42. </html>
Page
指向当前JSP页面本身，java.lang.Object
  1.  
  2.   <body>
  3.     <h1>page内置对象</h1>
  4. 	<hr>
  5. 	当前page页面对象的字符串描述：<%=page.toString() %>
  6.   </body>
PageContext
提供对JSP页面内所有对象及名字空间的访问
可以访问本页所在session---也可以application的某一属性
  1.  <body>
  2.     <h1>pageContext内置对象</h1>
  3. 	<hr>
  4. 	用户名是：<%=pageContext.getSession().getAttribute("username") %><br>
  5. 	<%//跳转到注册页面
  6. 	//pageContext.forward("req.jsp");
  7. 	//包含include.jsp内容
  8. 	pageContext.include("include.jsp");
  9. 	%>
  10.   </body>
  1. <%@page import="javax.enterprise.inject.New"%>
  2. <%@page import="java.text.*"%>
  3. <%@ page language="java" import="java.util.*" contentType="text/html; charset=UTF-8"%>
  4. <%
  5. String path = request.getContextPath();
  6. String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
  7. Date date=new Date();
  8. SimpleDateFormat sdf=new SimpleDateFormat("yyyy年MM月dd日");
  9. String s=sdf.format(date);
  10. out.println(s+"<br>");
  11. %>

Config
在一个Servet初始化时，JSP引擎向它传递信息，
Exception
是一个异常对象，
  1. <%@ page language="java" import="java.util.*"  contentType="text/html; charset=UTF-8" errorPage="exception.jsp"%>
  2. <!--  errorPage="exception.jsp"将异常交给 exception.jsp处理 -->
  3. <%
  4. String path = request.getContextPath();
  5. String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
  6. %>
  8. <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
  9. <html>
  10.   <head>
  11.     <base href="<%=basePath%>">
  12.     
  13.     <title>My JSP 'exception.jsp' starting page</title>
  14.     
  15. 	<meta http-equiv="pragma" content="no-cache">
  16. 	<meta http-equiv="cache-control" content="no-cache">
  17. 	<meta http-equiv="expires" content="0">    
  18. 	<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
  19. 	<meta http-equiv="description" content="This is my page">
  20. 	<!--
  21. 	<link rel="stylesheet" type="text/css" href="styles.css">
  22. 	-->
  24.   </head>
  25.   
  26.   <body>
  27.    <h1>测试异常页面</h1>
  28.    <%
  29.    System.out.println(100/0);//抛出算数异常
  30.    %>
  31.   </body>
  32. </html>
  1. <%@ page language="java" import="java.util.*"  contentType="text/html; charset=UTF-8" isErrorPage="true"%>
  2. <%
  3. String path = request.getContextPath();
  4. String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
  5. %>
  7. <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
  8. <html>
  9.   <head>
  10.     <base href="<%=basePath%>">
  11.     
  12.     <title>My JSP 'excepton.jsp' starting page</title>
  13.     
  14. 	<meta http-equiv="pragma" content="no-cache">
  15. 	<meta http-equiv="cache-control" content="no-cache">
  16. 	<meta http-equiv="expires" content="0">    
  17. 	<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
  18. 	<meta http-equiv="description" content="This is my page">
  19. 	<!--
  20. 	<link rel="stylesheet" type="text/css" href="styles.css">
  21. 	-->
  23.   </head>
  24.   
  25.   <body>
  26.    <h1>exception内置对象</h1>
  27.    异常消息:<%=exception.getMessage() %><br>
  28.    异常字符串描述：<%=exception.toString() %>
  29.   </body>
  30. </html>
用户登录例子：用户名admin,登陆成功内部转发login_success.jspbong提示成功，失败则请求重定向login_failure.jsp
indexs.jsp
  1. <%@ page language="java" import="java.util.*" contentType="text/html; charset=UTF-8"%>
  2. <%
  3. 	String path = request.getContextPath();
  4. 	String basePath = request.getScheme() + "://"
  5. 			+ request.getServerName() + ":" + request.getServerPort()
  6. 			+ path + "/";
  7. %>
  9. <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
  10. <html>
  11. <head>
  12. <base href="<%=basePath%>">
  14. <title>My JSP 'index.jsp' starting page</title>
  15. <meta http-equiv="pragma" content="no-cache">
  16. <meta http-equiv="cache-control" content="no-cache">
  17. <meta http-equiv="expires" content="0">
  18. <meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
  19. <meta http-equiv="description" content="This is my page">
  20. <!--
  21. 	<link rel="stylesheet" type="text/css" href="styles.css">
  22. 	-->
  23. </head>
  25. <body>
  26. 	<div id="container">
  27. 		<div></div>
  28. 		<div id="box">
  29. 			<form action="doologin.jsp" method="post">
  30. 				<p class="main">
  31. 					<label>用户名：</label><input name="username" value="" /> 
  32. 					<label>密码：</label><input	type="possword" name="password" value="" />
  33. 				</p>
  34. 				<p cclass="space">
  35. 					<input type="submit" value="登录" class="login" style="cursor:poin">
  36. 				</p>
  37. 			</form>
  38. 		</div>
  39. 	</div>
  40. </body>
  41. </html>
doologin.jsp
  1. <%@ page language="java" import="java.util.*"
  2. 	contentType="text/html; charset=UTF-8"%>
  3. <%
  4. 	String path = request.getContextPath();
  5. 	String basePath = request.getScheme() + "://"
  6. 			+ request.getServerName() + ":" + request.getServerPort()
  7. 			+ path + "/";
  8. 	String username = "";
  9. 	String password = "";
  10. 	request.setCharacterEncoding("utf-8");//防止中文乱码
  11. 	username = request.getParameter("username");
  12. 	password = request.getParameter("password");
  13. 	if ("admin".equals(username) && "admin".equals(password)) {
  14. 		session.setAttribute("loginUser", username);
  15. 		request.getRequestDispatcher("login_success.jsp").forward(
  16. 				request, response);
  17. 	} else {
  18. 		response.sendRedirect("login_failure.jsp");
  19. 	}
  20. %>
login_success.jsp
  1. <%@ page language="java" import="java.util.*" contentType="text/html; charset=UTF-8"%>
  2. <%
  3. 	String path = request.getContextPath();
  4. 	String basePath = request.getScheme() + "://"
  5. 			+ request.getServerName() + ":" + request.getServerPort()
  6. 			+ path + "/";
  7. %>
  9. <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
  10. <html>
  11. <head>
  12. <base href="<%=basePath%>">
  14. <title>My JSP 'index.jsp' starting page</title>
  15. <meta http-equiv="pragma" content="no-cache">
  16. <meta http-equiv="cache-control" content="no-cache">
  17. <meta http-equiv="expires" content="0">
  18. <meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
  19. <meta http-equiv="description" content="This is my page">
  20. <!--
  21. 	<link rel="stylesheet" type="text/css" href="styles.css">
  22. 	-->
  23. </head>
  25. <body>
  26. 	<div id="container">
  27. 		<div></div>
  28. 		<div id="box">
  29. 		<%
  30. 		  String loginUser="";
  31. 		if(session.getAttribute("loginUser")!=null){
  32. 			loginUser=session.getAttribute("loginUser").toString();
  33. 		}
  34. 		%>
  35. 			欢迎你<font color="red"><%=loginUser %></font>，登陆成功
  36. 		</div>
  37. 	</div>
  38. </body>
  39. </html>
login_failure.jsp
  1. <%@ page language="java" import="java.util.*" contentType="text/html; charset=UTF-8"%>
  2. <%
  3. 	String path = request.getContextPath();
  4. 	String basePath = request.getScheme() + "://"
  5. 			+ request.getServerName() + ":" + request.getServerPort()
  6. 			+ path + "/";
  7. %>
  9. <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
  10. <html>
  11. <head>
  12. <base href="<%=basePath%>">
  14. <title>My JSP 'index.jsp' starting page</title>
  15. <meta http-equiv="pragma" content="no-cache">
  16. <meta http-equiv="cache-control" content="no-cache">
  17. <meta http-equiv="expires" content="0">
  18. <meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
  19. <meta http-equiv="description" content="This is my page">
  20. <!--
  21. 	<link rel="stylesheet" type="text/css" href="styles.css">
  22. 	-->
  23. </head>
  25. <body>
  26. 	<div id="container">
  27. 		<div></div>
  28. 		<div id="box">
  29. 			登陆失败；
  30. 			<a href="index.jsp">返回</a>
  31. 		</div>
  32. 	</div>
  33. </body>
  34. </html>





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原文地址：https://www.cnblogs.com/liuruimiku/p/5405315.html