Java 如何更新会话属性
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How to update session attribute
提问by Vaishali
I have some session attributes being saved. I have a jsp page on which a call to a servlet is made through. This servlet updates one of the session variable but I am not able to see the reflection of these changes in my jsp.Pls help.
我保存了一些会话属性。我有一个调用 servlet 的 jsp 页面。此 servlet 更新会话变量之一，但我无法在 jsp.Pls 帮助中看到这些更改的反映。
In My servlet
在我的 servlet
List<DriverList> abc = dao.getABC();
request.getSession().removeAttribute("abc");
request.getSession().setAttribute("abc", abc);
In my jsp
在我的jsp中
function update()
{
var url = "updateServlet";
var req = $.ajax({
type: 'GET',
url: url,
cache: false,
type: "GET",
success: function()
{
latlng = [];
latlng = [<c:forEach var="test" items="${abc}">
[<c:out value="${test.latitude}"/>,<c:out value="${test.longitude}"/>,"<c:out value= "${test.name}" />",<c:out value="${test.cellNo}"/>],
</c:forEach> ];
},
error: function (status) {
}
});
}
The value of ${abc}is same as before. How to get the new value ?
的值${abc}与以前相同。如何获得新值？
The exact flow -
准确的流程——
when login servlet is called
abcvalue assessionAttributeis set.Now this redirects to base.jsp. I use abc for the first time. Now after every 30 seconds this
update()function is called. This update function calls a servlet through ajax where the session attribute abc is updated.In the success function of ajax request I want to use this new abc value but getting the old one again.
当登录 servlet 被调用时设置的
abc值sessionAttribute。现在这重定向到 base.jsp。我第一次使用 abc。现在每 30 秒
update()调用一次该函数。此更新函数通过 ajax 调用 servlet，其中更新会话属性 abc。在 ajax 请求的成功函数中，我想使用这个新的 abc 值，但再次获得旧的值。
回答by cherouvim
To access the abcvariable in the JSP try:
要访问abcJSP 中的变量，请尝试：
${sessionScope.abc}
Also note that removing before setting is usually redundant. So:
另请注意，在设置之前删除通常是多余的。所以：
request.getSession().removeAttribute("abc");
request.getSession().setAttribute("abc", abc);
Can simply become:
可以简单地变成：
request.getSession().setAttribute("abc", abc);
回答by Romen
I had similar problem. It turned out that when you use
我有类似的问题。原来，当你使用
HttpSession
object in your controller, it shouldn't be annotated using
控制器中的对象，不应使用
@SessionAttributes
