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Cookie中的三個容器request,session,application的設定和擷取

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public class SaveServlet extends HttpServlet {

public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doPost(request, response);
}

public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("text/html;charset=utf-8");
PrintWriter out = response.getWriter();
out.println("<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01 Transitional//EN\">");
out.println("<HTML>");
out.println(" <HEAD><TITLE>A Servlet</TITLE></HEAD>");
out.println(" <BODY>");

request.setCharacterEncoding("utf-8");
String name = request.getParameter("name");
String pwd = request.getParameter("pwd");
String info = name+","+pwd;
//把資訊分別儲存到3個容器中
request.setAttribute("info", info+" ---Request");
request.getSession().setAttribute("info", info+" ---Session"); //JSP頁面中的隱藏對象: session
getServletContext().setAttribute("info", info+" ---Application"); //JSP頁面中的隱藏對象: application

//一個小功能:實現讓使用者關閉瀏覽器之後，10分鐘之內身份還有效
//本質上就是向用戶端寫一個名為JSESSIONID的cookie--有效期間為10分鐘
String id = request.getSession().getId();
Cookie c = new Cookie("JSESSIONID",id);
c.setMaxAge(60*10);
c.setPath(request.getContextPath());
response.addCookie(c);

out.println(" </BODY>");
out.println("</HTML>");
out.flush();
out.close();
}

}

----------------------------------------------------------------------------------------------------------------------------

public class GetServlet extends HttpServlet {

public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doPost(request, response);
}

public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("text/html;charset=utf-8");
PrintWriter out = response.getWriter();
out.println("<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01 Transitional//EN\">");
out.println("<HTML>");
out.println(" <HEAD><TITLE>A Servlet</TITLE></HEAD>");
out.println(" <BODY>");

request.setCharacterEncoding("utf-8");
//把資訊分別從3個容器中讀取出來
String reqInfo = (String) request.getAttribute("info");
String sessionInfo = (String) request.getSession().getAttribute("info");
String appInfo =(String)getServletContext().getAttribute("info");

out.println("reqInfo:" + reqInfo);
out.println("sessionInfo:" + sessionInfo);
out.println("appInfo:" + appInfo);

out.println(" </BODY>");
out.println("</HTML>");
out.flush();
out.close();
}

}

--------------------------------------------------------------------------------------------------------------------------------------

<form action="SaveServlet" method="post">
姓名:<input type="text" name="name"/> <br/>
密碼:<input type="password" name="pwd"/> <br/>
<input type="submit" value="資訊儲存到3個容器"/>
</form>
<a href="GetServlet">顯示3個容器中的資訊</a><br/>

-----------------------------------------------------------------------------------------------------------------------------------------

顯示結果：request中是null而session跟application中有內容，可以那上面的代碼測試一下；

session中的安全結束代碼：

HttpSession session = request.getSession();
session.invalidate();//讓該session對象失效
out.println("已經安全退出");

//seesion是在網頁中，而application是在伺服器中，在不同的瀏覽器中session不同

 

Cookie中的三個容器request,session,application的設定和擷取

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