脚本程序
<> 或者，您也可以编写与其等价的XML语句，就像下面这样： <jsp:scriptlet> 代码片段 </jsp:scriptlet>任何文本、HTML标签、JSP元素必须写在脚本程序的外面。 ###中文编码问题 如果我们要在页面正常显示中文，我们需要在 JSP 文件头部添加以下代码：<>
JSP声明
JSP表达式
<%@ directive attribute="value" %>
JSP内置对象
1.内置对象简介（web容器创建的 ?不需要new）
- 四种作用域范围
- out（是JSPWriter的一个实例，是向客户端输出内容常用的对象）
void println();void clear() 清除缓冲区的内容
- request/response（请求与响应模式）
5 ?session - application
其他内置对象
JSP客户端请求
当浏览器请求一个网页时，它会向网络服务器发送一系列不能被直接读取的信息，因为这些信息是作为HTTP信息头的一部分来传送的
HTTP请求例子
在这个例子中，我们会使用HttpServletRequest类的getHeaderNames()方法来读取HTTP信息头。这个方法以枚举的形式返回当前HTTP请求的头信息。
获取Enumeration对象后，用标准的方式来遍历Enumeration对象，用hasMoreElements()方法来确定什么时候停止，用nextElement()方法来获得每个参数的名字
1 <%@ page language="java" contentType="text/html; charset=UTF-8" 2 ????pageEncoding="UTF-8"%> 3 <%@ page import="java.io.*,java.util.*" %> 4 <!DOCTYPE html> 5 <html> 6 <head> 7 <meta charset="utf-8"> 8 <title>菜鸟教程(runoob.com)</title> 9 </head>10 <body>11 <h2>HTTP 头部请求实例</h2>12 <table width="100%" border="1" align="center">13 <tr bgcolor="#949494">14 <th>Header Name</th><th>Header Value(s)</th>15 </tr>16 <%17 ???Enumeration headerNames = request.getHeaderNames();18 ???while(headerNames.hasMoreElements()) {19 ??????String paramName = (String)headerNames.nextElement();20 ??????out.print("<tr><td>" + paramName + "</td>\n");21 ??????String paramValue = request.getHeader(paramName);22 ??????out.println("<td> " + paramValue + "</td></tr>\n");23 ???}24 %>25 </table>26 </body>27 </html>JSP服务器响应
Response响应对象主要将JSP容器处理后的结果传回到客户端。可以通过response变量设置HTTP的状态和向客户端发送数据，如Cookie、HTTP文件头信息等。
HTTP响应头程序示例
<%@ page language="java" contentType="text/html; charset=UTF-8" ???pageEncoding="UTF-8"%><%@ page import="java.io.*,java.util.*" %><!DOCTYPE html><html><head><meta charset="utf-8"><title>菜鸟教程(runoob.com)</title></head><body><h2>自动刷新实例</h2><% ??// 设置每隔5秒自动刷新 ??response.setIntHeader("Refresh", 5); ??// 获取当前时间 ??Calendar calendar = new GregorianCalendar(); ??String am_pm; ??int hour = calendar.get(Calendar.HOUR); ??int minute = calendar.get(Calendar.MINUTE); ??int second = calendar.get(Calendar.SECOND); ??if(calendar.get(Calendar.AM_PM) == 0) ?????am_pm = "AM"; ??else ?????am_pm = "PM"; ??String CT = hour+":"+ minute +":"+ second +" "+ am_pm; ??out.println("当前时间: " + CT + "\n");%></body></html>?
Http状态吗实例
1 <html> 2 <head> 3 <title>Setting HTTP Status Code</title> 4 </head> 5 <body> 6 <% 7 ???// 设置错误代码，并说明原因 8 ???response.sendError(407, "Need authentication!!!" ); 9 %>10 </body>11 </html>
Get获取URL
1 <%-- 2 ??Created by IntelliJ IDEA. 3 ??User: tangwei9 4 ??Date: 2017/7/14 5 ??Time: 10:22 6 ??To change this template use File | Settings | File Templates. 7 --%> 8 <%@ page contentType="text/html;charset=UTF-8" language="java" %> 9 <%@ page import ="java.io.*,java.util.*"%>10 <html>11 <head>12 ????<title>GET方式请求实例</title>13 </head>14 <body>15 <h1>Get方式获取URL</h1>16 <u1>17 ????<li><p><b>站点名</b>18 ????<%= request.getParameter("name")%>19 ????</p>></li>20 ?21 ????<li><p><b>网址名</b>22 ????<%= request.getParameter("url")%>23 ?24 ????</p>></li>25 ?26 </u1>27 </body>28 </html>29 ? JSP Cookie
设置Cookie
<% ???String str ?= URLEncoder.encode(request.getParameter("name"),"utf-8");? ???// 设置 name 和 url cookie ???Cookie name = new Cookie("name",str);? ???Cookie url = new Cookie("url",request.getParameter("url"));? ???//设置Cookie的时间为1天? ???name.setMaxAge(60*60*24); ???name.setMaxAge(60*60*24);? ???//在响应头添加Cookie? ???response.addCookie(name); ???response.addCookie(url);???%>读取Cookie
1 <%@ page language="java" contentType="text/html; charset=UTF-8" ?2 pageEncoding="UTF-8"%> ?3 <%@ page import="java.net.*" %> ?4 ?5 <% ?6 Cookie cookie = null; ?7 Cookie[] cookies = null; ?8 // 获取cookies的数据,是一个数组 ?9 cookies = request.getCookies(); 10 if( cookies != null ){ 11 out.println(""); 12 13 for (int i = 0; i < cookies.length; i++){ 14 cookie = cookies[i];15 ?????out.print("参数名 : " + cookie.getName());16 ?????out.print("<br>");17 ?????out.print("参数值: " + URLDecoder.decode(cookie.getValue(), "utf-8") +" <br>");18 ?????out.print("------------------------------------<br>");19 ??}20 }else{ 21 out.println("没有发现 Cookie"); } 22 23 %> 删除Cookie
1 <%@ page language="java" contentType="text/html; charset=UTF-8" ?2 pageEncoding="UTF-8"%> ?3 <%@ page import="java.net.*" %> ?4 ?5 <% ?6 Cookie cookie = null; ?7 Cookie[] cookies = null; ?8 // 获取当前域名下的cookies，是一个数组 ?9 cookies = request.getCookies(); 10 if( cookies != null ){ 11 out.println("查找 Cookie 名与值");for (int i = 0; i < cookies.length; i++){ cookie = cookies[i]; 12 13 if((cookie.getName( )).compareTo("name") == 0 ){ 14 cookie.setMaxAge(0); 15 response.addCookie(cookie); 16 out.print("删除 Cookie: " + 17 cookie.getName( ) + "); 18 "19 } 20 out.print("参数名 : " + cookie.getName()); 21 out.print(""); 22 23 out.print("参数值: " + URLDecoder.decode(cookie.getValue(), "utf-8") +" "); 24 25 out.print("------------------------------------"); 26 27 } 28 }else{ 29 out.println("没有发现 Cookie"); 30 31 } 32 %> 33 34 ?JSP Session
1 <%@ page language="java" contentType="text/html; charset=UTF-8" ?2 pageEncoding="UTF-8"%> ?3 <%@ page import="java.io.,java.util." %> ?4 <% ?5 // 获取session创建时间 ?6 Date createTime = new Date(session.getCreationTime()); ?7 // 获取最后访问页面的时间 ?8 Date lastAccessTime = new Date(session.getLastAccessedTime()); 9 10 String title = "再次访问菜鸟教程实例"; 11 Integer visitCount = new Integer(0); 12 String visitCountKey = new String("visitCount"); 13 String userIDKey = new String("userID"); 14 String userID = new String("ABCD");15 16 // 检测网页是否由新的访问用户 17 if (session.isNew()){ 18 title = "访问菜鸟教程实例"; 19 session.setAttribute(userIDKey, userID); 20 session.setAttribute(visitCountKey, visitCount); 21 } else { 22 visitCount = (Integer)session.getAttribute(visitCountKey); 23 visitCount += 1; 24 userID = (String)session.getAttribute(userIDKey); 25 session.setAttribute(visitCountKey, visitCount); 26 } 27 %> 文件上传代码
http://www.runoob.com/jsp/jsp-file-uploading.html
重定向百度代码
1 <%2 ????String site = new String("http://www.baidu.com");3 ????response.setStatus(response.SC_MOVED_TEMPORARILY);4 ????response.setHeader("Location",site);5 ?6 %> 访问量统计
<% ???????Integer count = (Integer) application.getAttribute("count"); ???????if(count == null || count == 0){ ???????????out.print("<br>第一次访问</br>"); ???????????count = 1; ???????}else ???????{ ???????????out.print("欢迎访问本站"); ????????count++; ???????} ???????application.setAttribute("count",count);%><p>页面的访问量为:<%= count%></p>> ?发送邮件http://www.runoob.com/jsp/jsp-sending-email.html
JSP操作数据库
http://www.runoob.com/jsp/jsp-database-access.html
那些你常用的JSP知识
原文地址：http://www.cnblogs.com/arsense/p/7457149.html