Java HttpSession .getAttribute（字符串名称）
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Java HttpSession .getAttribute(String name)
提问by Display Name
I have a simple, short question but not found the answer anywhere. I created an HttpSession and want to get an attribute from it, for example a User object.
我有一个简单而简短的问题，但在任何地方都找不到答案。我创建了一个 HttpSession 并想从中获取一个属性，例如一个 User 对象。
HttpSession session = request.getSession(true);
Object userObject = session.getAttribute("name");
if ((userObject != null) && (userObject instanceof User)) {
User currentUser = (User) userObject;
...
}
The question is the following: .getAttribute function gets a String name as parameter - what is the name? From where do I know the name? Is it predefined somewhere? - then where to define another one?
问题如下： .getAttribute 函数获取一个字符串名称作为参数 - 名称是什么？我从哪里知道名字的？它是在某处预定义的吗？- 那么在哪里定义另一个？
Thank you!
谢谢！
回答by LeHill
Usually, you add attributes to the session yourself like so:
通常，您自己向会话添加属性，如下所示：
User someObject = new User();
session.setAttribute("pickaName", someObject);
Then you can get the session and pull off this attribute using that same name you used earlier like so:
然后您可以获取会话并使用您之前使用的相同名称取消此属性，如下所示：
User sameObject = (User) session.getAttribute("pickaName");
回答by Julian
.getAttribute function gets a String name as parameter - what is the name?
.getAttribute 函数获取一个字符串名称作为参数 - 名称是什么？
If you want to get attributes from Session, you need to set them to the Session before like so:
如果你想从 Session 获取属性，你需要像这样将它们设置到 Session 之前：
User aux = new User();
HttpSession session = new HttpSession();
session.setAttribute("myUserObject", aux);
User user = (User) session.getAttribute("myUserObject");
