How do I check that a session object contains a particular key/value entry

I want to check if a certain key/value pair has be开发者_如何学Goen set.

How do I check if a an entry with key named "keyName" exists. Sample code or a pointer to an example would be appreciated.

If you want to differ between "not set" and null, step through session.getAttributeNames() and search your key name.

Heres a simple introductory tutorial to JSP Sessions

In essence you should just need to check that session.getAttribute("keyName") is not null.