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java,web项目中的session。

2020-01-15 11:54 288 查看

对session的操作

package com.web.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;
import javax.servlet.http.HttpSession;

/**
* 对Session属性的操作
* @title SessionOperateServlet.java
*/
@WebServlet("/session")
public class SessionOperateServlet extends HttpServlet {
private static final long serialVersionUID = -823507841998757131L;

@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
String key = request.getParameter("name");

HttpSession session = request.getSession();

switch (key) {
case "add": // 添加属性
session.setAttribute("xxx", "1111");
session.setAttribute("yyy", "yyy");
break;
case "remove": // 删除属性
session.removeAttribute("yyy");
break;
case "modify": // 修改属性
session.setAttribute("xxx", "2222");
response.getWriter().print(session.getAttribute("xxx"));
break;
case "all": // 消毁Session
session.invalidate();
break;
}
}
}

演示session的用法

package com.web.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;
import javax.servlet.http.HttpSession;

/**
* 演示Session的Servlet
* @title SessionServlet2.java
* Cookie: JSESSIONID=6F011446DA5E07440A06F3757EC78147
* Cookie: JSESSIONID=8F6AB4574C88B63E624ACCD039747556
* Cookie: JSESSIONID=DC91EE8D9806D180C27EC1216E3E6C1E
* Cookie: JSESSIONID=F31EECBE099313E9847715975BCA6611
*/
@WebServlet("/servlet2")
public class SessionServlet2 extends HttpServlet {
private static final long serialVersionUID = 2008865399088388474L;

@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// 创建Session对象
// 说明:getSession(boolean create);如果使用这个方法,当
// session不存在时就创建一个新的,如果使用getSession(),当
// session不存在时就返回一个null
HttpSession session = request.getSession();

response.setContentType("text/html; charset=utf-8");

// 从Session中获取指定的名称
String name = (String)session.getAttribute("name");
Object age = session.getAttribute("age");
if (name != null) {
response.getWriter().print(name+"<br/>");
response.getWriter().print(age+"<br/>");

// 如果要删除Session中的指定名称,可以使用removeAttribute(name)方法
session.removeAttribute("name");

response.getWriter().print("------------<br/>");

Object n = session.getAttribute("name");
Object a = session.getAttribute("age");

response.getWriter().print(n+"<br/>");
response.getWriter().print(a+"<br/>");

// 如果要删除Session中所有数据,则需要使用如下方法:
session.invalidate(); // 删除所有数据

response.getWriter().print("------------<br/>");

n = session.getAttribute("name");
a = session.getAttribute("age");

response.getWriter().print(n+"<br/>");
response.getWriter().print(a+"<br/>");
} else {
System.out.println("没有Session");
}
}
}

session2

package com.web.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;
import javax.servlet.http.HttpSession;

/**
* 演示Session的Servlet
*
* @title SessionServlet.java
* @author 姚臣伟
* @company 慧与(中国)
* @date 2019年10月12日
*/
@WebServlet("/servlet1")
public class SessionServlet extends HttpServlet {
private static final long serialVersionUID = 3871869978555454629L;

@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// 获取Session对象
HttpSession session = request.getSession();
// 向Session对象添加一个值
session.setAttribute("name", "jock");
session.setAttribute("age", 20);
// 重定向到servlet2
response.sendRedirect(request.getContextPath() + "/servlet2");
}
}
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