JSESSIONID description in cookie

1) When you access the server for the first time, you will see the Set-Cookie information in the response header (this information will only appear in the response header when you access the server for the first time)

The picture above JSESSIONID=ghco9xdnaco31gmafukxchph;Path=/acr,

The browser will set the browser's cookie according to the set-cookie information in the response header and save it

Note that this cookie will be lost when the browser is closed because the cookie expiration date is not set.

2) When the request is made again (not the first request), the browser will send the cookie to the server in the request header (this is the case for every request)

 (JSESSIONID=ghco9xdnaco31gmafukxchph)

It is not difficult to find that the jsessionid of this is the same as the above jsessionid

We can also prove that our company also put the session id in the cookie, and you can see that the jsessionid is the same as the session id, as follows:

3) Why is this cookie sent on every request except the first request (in this case, the jsessionid to be exact)?

In fact, when a user accesses the server, a session will be opened for each user. How does the browser determine which user the session belongs to?The role of jsessionid is reflected: jsessionid is used to determine which session the current user corresponds to.In other words, the way for the server to identify the session is to tell the server where the client's session is in memory through jsessionid.

In fact jsessionid ==request.getSession().getId()

4) To sum up, the workflow of jsessionid can be simply represented by the following diagram: