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session
//a页面
<% request.getSession().setAttribute("key","session");%>
<%=session.getId() %>
<a href="requestPage.jsp">点击</a>
//跳转页面<%=session.getAttribute("key")%>
<%=session.getId() %>
getSession() //创建session对象，用requst对象调用，参数：true:自动创建，false:不创建
session.getId() //获取session的id
session.setMaxInactiveInterval(1*60*60) //设置session自动销毁时间，以秒为单位，这里是1小时
session.setAttribute("session", "12345678"); //往session域存储数据，object类型
session.getAttribute("session"); //取数据，取出是object类型
session.removeAttribute(“session”); //删除session域中指定的数据
2. request
通过该对象获取用户提交的信息 request.getParameter();
该对象包含了当前用户请求的上下文，包括表单信息，传递的参数信息等
还可以通过次对象获取session对象
HttpSession session=request.getSession();
本页面即可获得数据：
<form >
姓名：<input type="text" name="name" length="20">
账号:<input type="text" name="id" length="20">
<input type="submit" value="go"><br>
</form>
<%=request.getParameter("name") %><br>
<%=request.getParameter("id") %><br>
<%! String a,b; %>
<%
if (request.getParameter("name")==null){
a=request.getParameter("name");
}
if (request.getParameter("id")==null){
b=request.getParameter("name");
}
%>
String username=request.getParameter("username");
//解决get请求中文乱码问题
username=new String(username.getBytes("iso-8859-1"),"utf-8");
不同页面跳转，使用action，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;
/**
* Servlet implementation class s1
*/
@WebServlet("/s1")
public class s1 extends HttpServlet {
private static final long serialVersionUID = 1L;
public s1() {
super();
// TODO Auto-generated constructor stub
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
System.out.println("hello");
request.setAttribute("name","Feathers");
request.getRequestDispatcher("requestPage.jsp").forward(request, response);
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doGet(request, response);
}
}
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<%@page import="java.util.*" %>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<body>
<form action="s1">
姓名：<input type="text" name="name" length="20">
账号:<input type="text" name="id" length="20">
<input type="submit" value="go"><br>
</form >
<%=request.getParameter("name") %><br>
<%=request.getParameter("id") %><br>
<%! String a,b; %>
<%
if (request.getParameter("name")==null){
a=request.getParameter("name");
}
if (request.getParameter("id")==null){
b=request.getParameter("name");
}
// 向request域中存入一个键值对
%>
</body>
</html>
<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
pageEncoding="ISO-8859-1"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="ISO-8859-1">
<title>Insert title here</title>
</head>
<body>
hey@
<%System.out.println((String)request.getAttribute("name")); %>
</body>
</html>
request.getRequestDispatcher()：（带数据）
request.getRequestDispatcher("想跳转的servlet名").forward(request, response);
request.getRequestDispatcher("文件路径").forward(request, response);
3.Response
该对象常常被用来完成页面的跳转、页面的自动刷新、页面的自动跳转、禁用缓存等功能
页面跳转的方法：
response.sendRedirect("页面的路径");
页面自动刷新的方法：
response.setHeader("refresh",3);每隔3秒刷新一次
页面自动跳转的方法：
response.setHeader("refresh","3;URL=commom.jsp?ref=aaa");
指定3秒后自动跳转到common.jsp页面并传递了值为aaa的参数ref
禁用缓存的方法：
response.setHeader("Cache=Control","no-cache");
response.serHeader("Pragma","no-cache");
response.setHeader("Expires",0);
禁用缓存后，当我们单击后退时，客户端会自动想服务器请求上一次页面