java，web项目中的session。

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"); } }